ALL ROADS LEADS TO ROME

My visit to Mahabalipuram(mamallapuram)

2010-08-26T04:42:00.000-07:00

Hai,

Recently i visited Mahabalipuram ,the ancient port city of Pallavas .The ancient city Really Enthralled me.

I have no words to explain but i will try to give full view of the ancient (truly these are the pride and honor for Indians) marvelous city.

I have seen Rock cut caves and Temples and See shore temple and other monuments which are built by narasimhavaraman- I and his successors . the period of construction is in between 8 th century A.D to 10 th century A.D.

The see View is also very good and i enjoyed whole day with my childhood friends doctor sreekanth and Gopi.....

if you have a time and if you want see the other end of the world you can visit this gift given by the Pallavas.

Mahabalipuram

2010-08-26T04:25:00.000-07:00

Mahabalipuram (Source: Archeological Survey of India, Wikipedia)

Mahabalipuram,derived from 'Mamallapuram' is a town in Kancheepuram district in theIndian state of Tamil Nadu. It has an average elevation of 12 metres (39 feet).

Mahabalipuram was a 7^th century port city of the South Indian dynasty of the Pallavas around 60 km south from the city of Chennai in Tamil Nadu. The name Mamallapuram is believed to have been given after the Pallava king Narasimhavarman I, who took on the epithet Maha-malla (great wrestler), as the favourite sport of the Pallavas was wrestling.

Mahabalipuram (or Mamallapuram) was a celebrated port city of the Pallavas. It has been identified as the port Melange mentioned in the Periplus of the Erythraean Sea by an unknown Greek navigator of the first century A.D.

The monuments at Mahabalipuram are of different types like the rock-cut cave temples, monolithic temples, bas-relief sculptures and structural temples besides excavated remains of temples. The Pallava dynasty, which ruled this area between 6th-9th centuries A.D., patronised the creation of these wonderful edifices. Among them, Mahendravarman (AD 580-630), his son Narasimhavarman I Mamalla (AD 630-668), Paramesvaravarman (A.D. 672-700) and Narasimhavarman II Rajasimha (A.D. 700-728) contributed the most in developing Mahabalipuram as a centre of art and architecture. Many monuments remain unfinished.

Cave temples

Varaha cave

General view of Varaha Cave

The mandapa in the front has two lion- pillars and two pilasters, and beyond this in the centre, the cell is guarded by two dwarapalas. There are four panels on the walls of front mandaparepresenting Varaha raising goddess earth from the ocean. (Bhuvaraha panel), Gajalakshmi seated on lotus and bathed by elephants, Durga with four arms and Trivikrama overcoming the demon king Bali. The delineation and modelling of the figures are remarkable.

Bhuvaraha Panel, Varaha Cave

Gajalakshmi Panel, Varaha Cave

Four armed Durga, Varaha Cave

Trivikrama Panel, Varaha Cave

Mahishamardini cave

The cave has a front mandapa with a triple cell with four pillars and two pilasters. On either side of this mandapa two large panels one representing Seshasayi Vishnu and other Mahishamardhini. The central cell is intended for a Siva Linga; on the wall behind is the representation of Somaskanda.

Seshasayi Vishnu Panel, Mahishamardini Cave

Mahishamardini Panel, Mahishamardini Cave

Close up details of Mahishamardini Panel

Dharmaraja Mandapa

The triple celled cave temple with massive pillars belongs to Mahendravarman’s time. The cave temple contains inscription in Pallava grantha which gives the name of the temple asAtyantakama Pallavesvara -griham

Panchapandava mandapa

A large cave temple of which only six lion pillars and similar pilasters at either end are finished. The brackets above the capitals of these pillars are decorated with lions and griffins with human riders. The pillars and Pilasters with vyala base mounted on square pitha

Kotikal Mandapa is a small primitive rock cut temple of Mahendra style devoted to Durga. The façade shows two massive pillars and pilasters at either side end. In the centre of the back wall a cell has been cut and is guarded by female door keepers on either side of the entrance. There is an inscription with 7th century letters-Sri Vamankusa.

Koneri Mandapa

An unfinished five celled rock cut temple with four pillars supported by couchant lions and flanked by pilasters and with a central cell.

Trimurthi cave

A Triple celled temple with superstructure is believed to be dedicated to Brahma, Vishnu and Siva, the three gods of the Hindu pantheon. The entrance of each cell is flanked by dvarapalas in narrow panels.

The Monolothic temples

There are about nine monolithic temples at Mahabalipuram. They are the unique contribution of the Pallavas to Indian Art. The monolithic temples are called locally as Ratha (Chariot) as they resemble the processional chariots of a temple. The Five rathas, the best of all monolithic temples, are hewn out of a huge boulder. Temples of different plan and elevation have been carved and the left over portions were intelligently used to carve animals in a natural way. The naming of these ratha, after Pandavas and their wife, the heroes of epic Mahabharata, is simply a local tradition.

General view of the Monolithic temples, known as Five Rathas, From left to right: Draupadi, Nakula-Sahadeva, Bhima and Dharmaraja Rathas

Dharma raja ratha

Dharma raja ratha

Among the Five rathas, Dharmaraja ratha is the most impressive and sculpturally rich. The tritala (three storeyed) vimana, square in its talas but octagonal in the griva sikhara region, faces west.The sculptures around the sanctum in the corner blocks depict simple forms of Siva, Harihara, Brahma-Sasta, Brahma, a delicately balanced representation of Ardhanarisvara besides a portrait of a king, possibly Narasimhavarman I himself above which his titles Sri Meghaand Trailokiya –vardhana-vidhi are inscribed. The upper floors, a veritable gallery of images, have excellently modelled images of Siva as Gangadara, the earliest representation of Siva as Natesa in the Tamil country, Vrishbantika, Kankalamurti, Vishnu resting on Garuda, and Kaliyamardhana. An inscription gives the name of the sanctum in the uppermost tier as Atyantakama Pallavesvaram, Atyantakama being a title of Paramesvaravarman I.

Bhima Ratha

This monolithic ratha is oblong in plan and having an ekatala vimana possibly intended to be dedicated to the reclining form of Vishnu. Only the impressive Sala -Sikhara is fully finished and there is a hara above the ground storey and has high griva wall. The Sala roof carries boldnasikas to carry a row of Stupis and Astradeva trident-finials at the apexes of gable ends. The gable ends is brilliantly relieved with decorative motifs and at the centre is a miniature model of a square, ekatala shrine with circular and crowning stupi.

Bhima Ratha

Arjuna Ratha

This monolithic Vimana is one among five that carved out of a live rock. This small dvi-tala (two tiered) vimana consists, on plan a garbhagriha with a pillared Mukhamandapa. It shares an Upa Pitha with Draupathi ratha. The adhisthana is of simple Padabandha type. The pada portion has slit-niches between elegantly carved pillars carrying very handsome figures of Parthiharas,Amaras, a Siddha, a Chowri bearer, apsaras, and various deities like Vishnu, Skanda on elephant and Siva-Vrishabhantika. The upper tala (Storey) carries a hara with octagonal sikhara. There is a stupi carved out of the live rock but not detached from it, possibly to crown the Sikhara of the Vimana.

Arjuna Ratha

Draupathi Ratha

This is the smallest and the northern most of five monolithic rathas. It illustrates a simple hut-likeKutagara-Vimana. It shares an upapitha with Arjuna ratha. In elevation, the vimana has a simple padabandha adhisthana. The pada portion has devakoshtas containing images of Durga. The usual kapota is not to be seen. The roof, shaped like a hut with decorative motif in the joints. There is stupi carved out of the bedrock in a corner of the upapitha but yet to be detached from it. The sanctum bears an excellent depiction of Durga, possibly of later period.

Draupadi Ratha

Sahdeva Ratha

This monolithic ratha has an apsidal (Gajapriishta) plan from base to sikhara, recalling the earlierchaitya models. It is carried out of an independent boulder, stands near the Arjuna ratha and faces south. It has a dvitala vimana (two storeyed). The adhistana of this vimana is not defined. The pada is simple punctuated by pilasters. There is a mukha- mandapa in the front.

Sahadeva Ratha

The other monolithic temples worth mentioning are Ganesha ratha and Pidari ratha.

Ganesha Ratha

Arjuna Penance

Arjuna’s penance is an impressive bas-relief, datable to Narasimhavarman I’s period, suggestively depicts the story of Kiratarjuniya, wherein Arjuna, the great warrior hero of the Mahabharata, obtained the all-pervading Pasupatha weapon from Siva after a gruelling fight and severe penance. Siva and an emaciated Arjuna, doing penance, are shown prominently at the centre. The artist has excelled in imagination by placing the scene by the side of a river, judiciously suggesting the natural cleft as a river by depicting a naga and nagini. The peace and calm of the situation further enhanced by the presence of Chandra, Surya, Kinnaras, Ghandarvas, Apsaras etc., hunters carrying the hunt, host of animals, sages doing penance in front of a temple and Brahmins doing the mid-day rituals. The deer resting at ease by the side of a lion and the rats frolicking around the wily cat doing penance on hind legs have only enhances the mood. Depicting the animals in the most natural form and in right proportion is a testimony to the skilful execution by the artist.

Arjuna's Penance Panel

Govardhanadhari Panal

Govardhanadhari Panel

The huge bas-relief with a hall (mandapa) of 16th century added in front depicts the story of Krishna lifting the Govardhana hill to protect the cowherds and the cattle from the storm raised by Indra. The central figure of Krishna, with Balarama by his side, is shown lifting the hill with his little finger. Enjoying the divine protection, the rest are carrying on their business as usual. The artist suggests this by depicting a gopa (cowherd) milking a cow while the cow itself is fondly licking its calf. Another cowherd is seen playing a flute while the gopis carry a pile of pots. A woodcutter strolls with an axe. While one child enjoys the warmth of her mother, another takes a ride over the shoulder of an old man. The hill itself is a habitat for lions, griffins and sphinxes. This is the best representation of this story in the art of India.

Structural temples

Among the structural temples, the Shore temple consisting of two graceful Siva temples –Kshatryasimhesvaram (east) and Rajasimhesvaram (west), built by Pallava King Rajasimha (AD 700-728), mark the culmination of the architectural efforts begun with the carving of monolithicrathas. The western shrine has an outer wall (prakara) and a simple entrance tower (gopura). The elevation is gracefully proportioned. Located in between is an earlier shrine for reclining Vishnu (Narapatisimha Pallavagriham). It has no superstructure.

Shore Temple

All the names of these shrines represent Rajasimha’s various titles. The outer enclosure withnandis is of later period. Fully aware of inherent problems of this scenic location, the architects built the temple on a rock outcrop jutting from the sea. The use of hard stones like granite and leptinite, could not stop the erosion by abrasive wind and salty surroundings. The groyne wall, the plantation and periodic extraction of salt in recent times have checked this effect. The outcrop itself was utilized for carving several masterpieces like the excavated miniature shrine, Bhuvaraha image, Vishnu shrine, and the Mahishamardhini shrine with the beautifully carved deer.

Other structural temples worth mentioning are the Mukundanayanar and Olakkanesvara temples.

Excavated Remains

Sustained removal of the sand in the last century brought to light several buried structures around the Shore temple. Unique among them is the early Pallava stepped structure, approximately 200 m long. This structure is running north to south parallel to the sea. The exact purpose of this massive edifice is still uncertain. The steps are built of interlocking granite slabs over a laterite core. The intelligent interlocking method used here prevented the slabs from collapsing and recalls the megalithic traditions.

Stepped structure in front of Shore Temple

Accidentally discovered in 1990, the Bhuvaraha image, the miniature shrine and the well belongs to Pallava King Narasimhavarman Mamalla’s (AD 638-660) reign, but enclosed by an elliptical enclosure of Rajasimha’s (AD 700-728) period. These remains are carved on the live bedrock containing the reclining Vishnu.

Miniature Shrine to the north of Shore Temple

Close up details of Miniature Shrine and Varaha

The miniature shrine, dedicated to Siva, has its sixteen-side base carved out of the bedrock while the circular wall and superstructure are structural. Its form is unique and differs from all other single tier temples of Pallava period. The Bhuvaraha is shown retrieving the Mother Earth symbolically from the deep ocean. It was intentionally broken for unknown reasons. The base is inscribed with titles of the Pallava king Rajasimha. The enclosure wall built possibly to arrest sand from covering the remains contains an inscription in Pallava-Grantha script on the topmost course equating the king in pun with Arjuna.

Recently, remains of two temples were excavated, one to the south of Shore temple and another massive brick temple of Subrahmanya near the Tiger Cave at Saluvankuppam, a hamlet about 7 km from here.

Subrahmanya Temple, Saluvankuppam, view from north

Subrahmanya Temple, Saluvankuppam, view from south

Ticket Rates:

For Shore temple and Five rathas: Rs. 10 for Indian citizens and Rs.250/- or US $ 5 for others. Admission is free for all below the age of 15
A ticket purchased at one monument is valid at the other
Admission to the rest of the monuments located in the hillock area and other places is free as of now
No fee for still photography with handheld cameras.
Rs. 25/- for videography with handheld cameras. A simple form may be filled at the counter to get permission
For all other types of photography and videography, the Superintending Archaeologist, A.S.I ,Chennai Circle, Chennai-9 may be contacted (Ph. 044- 25670396/25670397)

Hours of opening:

0600 hrs to 1800 hrs on all days. Sale of admission tickets will be closed at 1730 hrs.

Approach:

Mahabalipuram is about 58 km from Chennai on the East Coast Road and well connected by public and private transport. The nearest airport is located at Chennai.
Photo Gallery
Surya, monument known as Dharmaraja ratha, east wall, 7th century A.D.
Monkey group, Arjuna's penance, 7th century A.D.
Seshasayi Vishnu, Mahishamardini cave, 7th century A.D
Devi killing Mahisha, Mahishamardini cave, 7th century A.D.
Group of Monuments at Mahabalipuram

Hampi - My favorite Tourist Spot

2010-08-20T23:17:00.000-07:00

Hampi

Hampi is a village in northern Karnataka state, India. It is located within the ruins of Vijayanagara, the former capital of the Vijayanagara Empire. Predating the city of Vijayanagara, it continues to be an important religious centre, housing the Virupaksha Temple, as well as several other monuments belonging to the old city.

The name is derived from Pampa, which is the old name of the Tungabhadra River on whose banks the city is built. The name "Hampi" is an anglicized version of the Kannada Hampe(derived from Pampa). Over the years, it has also been referred to as Vijayanagara and Virupakshapura (from Virupaksha, the patron deity of the Vijayanagara rulers).

Hampi is identified with the historical Kishkindha, the Vanara (monkey) kingdom mentioned in the Ramayana. The first historical settlements in Hampi date back to one CE.

Hampi formed one of the cores of the capital of the Vijayanagara Empire from 1336 to 1565, when it was finally laid siege to by the Deccan Muslim confederacy. Hampi was chosen because of its strategic location, bounded by the torrential Tungabhadra river on one side and surrounded by defensible hills on the other three sides.

The site is significant historically and architecturally. The topography abounds with large stones which have been utilized to make larger than life statues of Hindu deities. A structure of historic importance appears every quarter of a mile. The Archaeological Survey of India continues to conduct excavations in the area, to discover additional artifacts and temples.
Geography

Hampi is situated on the banks of the Tungabhadra river. It is 353 km from Bangalore and 74 km away from Bellary. Hosapete (Hospet), 13 km away, is the nearest railway head. The chief languages spoken are Kannada and Telugu. The principal industries of the village areagriculture, the support of the Virupaksha temple and some other local holy places in the vicinity, and tourism. The annual Vijayanagar Festival is organized by the Government of Karnataka in November.

Due to the presence of several mineral deposits in this region (iron-ore, manganese), mining has been going on for many years now. But a recent boom for the supply of iron-ore in the international market has led to excessive mining in this district. The World Heritage Site at Hampi as well as the Tungabhadra Dam are now under threat.

Temples

Hampi has various notable Hindu temples, some of which are still active places of worship. Most notable ones are:Virupaksha Temple complex: Also known as the Pampapathi temple, it is a Shiva temple situated in the Hampi Bazaar. It predates the founding of the Vijayanagar empire. The temple has a 160-foot (49 m) high tower at its entrance. Apart from Shiva, the temple complex also contains shrines of the Hindu goddesses Bhuvaneshwari and Pampa.

Hampi - the story that unrevealed

2010-08-20T22:45:00.000-07:00

HAMPI- THE VIJAYANAGARA KINGDOM

Saint Vidyaranya established the seat of Vijayanagara empire in 1336 A.D, with the help of his devotee disciples Hakka and Bukka. The empire later became famous for its support towards renovation/reconstruction of temples through out India. It also became renowned for re-establishment of Indian culture, its support for music, art and literature. With the prime purpose of caring for the people and their welfare, this empire stretched physically covering Karnataka, Andhra and Maharashtra and became a by-word for golden rule.

Inside Vittala Temple

HAMPI, the seat of the famed VIJAYANAGARA empire was the capital of the largest empire in post-mogul India, covering several states. The empire reigned supreme under Krishnadevaraya, the Emperor. The Vijayanagara empire stretched over at least three states – Karnataka, Maharashtra, and Andhra Pradesh. The destruction of Vijayanagar by marauding Moghul invaders was sudden, shocking and absolute. They reduced the city to ruins amid scenes of savage massacre and horrors beggaring description.

Narasimha Monolith

Virupaksha Temple

The Ruins of Vijayanagara

Although in ruins today, this capital city once boasted riches known far beyond the shores of India. The ruins of Hampi of the 14th Century lies scattered in about 26 sq. km area, amidst giant boulders and vegetation. Protected by the tempestuous river Tungabhadra in the north and rocky granite ridges on the other three sides, the ruins silently narrate the story of grandeur splendor and fabulous wealth. The splendid remains of palaces and gateways of the broken city tells a tale of men infinite talent and power of creativity together with his capacity for senseless destruction.

Stepped Tank

Street view Of Vijayanagara Kingdom

View of Chariots

Strewn over a large area (about nine square miles) the ruins at Hampi offers to the tourist a remainder of the greatest land in the whole world. Every rock, every path and every monument at Hampi speak the same language; a language of glory and beauty.

View of Virupaksha Temple

The Chariot ( Beautiful Art)

Inside Virupaksha Temple (Musical Stones)

View from Virupaksha temple (Vijayanagara)

Stone Sculpture vishnumurthi

Ruined Temple

The Rathas

In March 2002, the Government of India has announced that Hampi would be developed as an international destination centre. The State Govt will constitute a Hampi World Heritage Area Management Authority for integrated development and conservation of Hampi.

Hampi - the story that unrevealed

2010-08-20T22:31:00.000-07:00

Lotus Mahal In Hampi

2010-08-18T03:06:00.000-07:00

When i was a child i was listen to my father about Hampi, he told me about the greatness of Sri Krishnadevaraya and the beauty of Vijayanagara Kingdom, the picture above is virupaksha Temple in Hampi(Vijayanagara).

Pavemnt analysis and design III

2010-01-28T00:15:00.000-08:00

1.3. INNOVATIVE APPLICATIONS

Innovative applications may be construction method based or design principle based. Some of the relevant issues are discussed in the following.

1.3.1 Construction Method Based

A mixture of aggregate and binding material, at varied proportions, constitute various specifications for road construction, for example, bituminous concrete, built-up spray grout, wet mix macadam, lean cement concrete etc. Discussion on all these standard specifications have been skipped here, rather, some specific mixes and their construction methods are discussed.

Emulsified bituminous mix

Cold emulsified bituminous mix (EBM) is gaining more and more acceptance for its environmental friendliness and less hazardous construction process. A relative comparison between the EBM and hot bituminous mix (HBM) has been presented in Table 4. It may be noted that though the rate of strength gain in EBM is slower (refer Figure 7), the final strength of EBM is comparable to that of HBM.

Table 4. Comparison of hot bituminous mix (HBM) and emulsified bituminous mix (EBM)

Property	HBM	EBM
Heating	Strong heating required, oxidative hardening occurs	No heating required, so no oxidative hardening
Setting time	Low	High
Applicability	Clear weather with high ambient temperatures	All weather (wet surfaces, rainy seasons, cold)
Convenience	Relatively difficult construction than EBM	Relatively easy construction
Energy	Relatively higher requirement	Relatively lower requirement
Uniqueness	Modifiers needed	Inherent anti-stripping agents
Economy	Less costly	More costly
Safety	Hazards from fuming, fire and environmental pollution	Free from such hazards

Foamed bituminous mix

Foamed bituminous mix (FBM) is a foamed mixture of air, water and bitumen. It is produced by injecting very small quantity of water into the hot bitumen, resulting in spontaneous foaming and temporary alteration of the physical properties of the bitumen. Figure-8 represents schematically the manufacture of FBM.
Although the foamed bitumen technology was developed more than forty years ago, it is now gaining popularity owing to its good performance, ease of construction and compatibility with a wide range of aggregate types (Transportek 1998).
Usage of FBM results in reduction in binder content and transportation costs, as it requires less binder and water than other types of cold mixing methods.
FBM can be compacted immediately and can carry traffic almost immediately after compaction is completed ( Jenkins et al., 2003 ).
The strength characteristics of FBMs are highly moisture dependent. This is because of the relatively low binder content and high void content of foamed bituminous mixes.
FBMs are not as temperature susceptible as HBM. Since larger aggregates are not coated with binder, the friction between the aggregates is maintained at higher temperatures.
Foamed bitumen can achieve stiffness comparable to those of cement-treated materials, with the added advantages of flexibility and fatigue resistance (Ramanujam and Kendall, 1999).
FBMs usually lack resistance to abrasion and raveling and are not suitable for wearing/friction course applications.

Figure - 8 Schematic presentation of FBM manufacture ( Romanoschi 2003 )

Some specific situations where use of foamed bitumen technology can be considered are:

• A pavement which has been repeatedly patched to the extent that pavement repairs are no longer cost effective.

• A weak granular base overlies a reasonably strong subgrade.

• Granular base too thin to consider using cementations binders.

• Can be effectively used in desert road stabilization etc. (Jenkins et al., 2003).

Relatively high cost, requirement of specific equipment for mix production, sensitivity to aggregate grading and stripping risk are some of the disadvantages with the foamed bituminous mix ( Jenkins et al., 2003 ).

Fiber reinforced bituminous mix

Addition of various kinds of fibers to the binder and aggregates during mix preparation process results in fiber reinforced bituminous mix (FRBM). Fibers are generally blended with bitumen binder before mixing it with the aggregates to achieve complete coating and even distribution throughout the mix. Research shows that FRBMs develop good resistance to aging, fatigue cracking, moisture damage, bleeding, reflection cracking etc. (Serfass and Samanos, 1996; Maurer et al., 1989).

Ultra-thin white topping

Overlaying technique of pavement rehabilitation is well known and widely practiced. However, ultra thin whitetopping (UTW) of concrete over existing bituminous pavement is a relatively new concept. UTW can be designed for low-speed, low volume traffic areas such as street intersections, aviation taxiways and runways, bus stops and tollbooths.

In this technique, a thin layer of high-strength, fiber-reinforced concrete is placed over a clean, milled surface of distressed bituminous concrete pavement to achieve a full or partial bonding. Bonding makes the two layers behave as a monolithic unit and share the load. Due to bonding, the neutral axis in concrete shifts from the middle of concrete layer towards its bottom. This results in a lowering of stresses at the bottom of concrete layer. Thick composite section behavior causes the corner stresses to decrease. On the other hand, downward shifting of neutral axis may cause critical load location to shift from edges to corners thus increasing the corner stresses. Short joint spacing is used to decrease the slab area that can curl or warp thus minimizing the corresponding stresses (MTTP 2004). A schematic diagram of UTW have been presented inFigure-9.

Figure -9 Flexible composite pavement using UTW

UTW is an excellent resurfacing option for deteriorated bituminous pavements which otherwise require frequent repair or overlays.

Following are some of the advantages of a UTW system (CAC 2004, Murison 2002):

• It is beneficial for repair of roads and intersections having problems of rutting, cracks, and poor drainage.

• It provides improved skid resistance.

• Its light colour reflects more light than bituminous pavement.

• Its heat-reflecting property can help to lower the average city temperature.

• It is less costly to maintain, than conventional flexible pavements, and does not require frequent resurfacing and repairs.

• The UTW concrete resists bitumen aging.

• The UTW concrete prevents degradation of bituminous surface due to fuel spills.

• It causes minimal traffic disruption due to faster construction and repair procedure.

• Its small panels are ideal for utility maintenance.

Bituminous recycling

In recycling method, bitumen and aggregates are separated out (partly or fully) and used again. The specific benefits of recycling of bituminous pavement can be summarized as:

Conservation of energy and construction material.
Prevention of undesirable rise in height of finished surface and preservation of the existing road geometrics.
Reuse of deteriorated road materials which in turn solves the disposal problem.
Solution to the problem of scarcity of good quality material.
Preservation of the environment.
Reduction in susceptibility to reflection cracking.

Bitumen ages due to oxidation with atmospheric oxygen as a result of which resins get converted into asphaltenes (Petersen, 1984). By this process bitumen loses its ductility and becomes more brittle. Recycling is based on the fact that bitumen obtained from old deteriorated bituminous pavement, may still has its residual properties and recycling helps in restoring those residual properties of the bitumen.

To judge the suitability for use as a recycled material, aggregates are tested for their gradation and bitumen is tested for its engineering properties. The optimum quantity of reclaimed material to be mixed with fresh material is generally determined from mix design process. Fresh thin (soft grade) bitumen having low viscosity can be used to replenish the aged bitumen. Rejuvenators (like road oils and flux oils) are sometimes added for improvement in properties of reclaimed bitumen.

There are four major technologies exist for bituminous pavement recycling (NCHRP-452). They are

(i) Hot mix recycling

Here recycled asphalt pavement ( RAP) is combined with fresh aggregate and bituminous binder or recycling agent in a hot mix plant. Mix is transported to paving site, placed, and compacted.

(ii) Cold in-place recycling

In this the existing pavement is milled up to a depth of 75 to 100mm, RAP, if necessary and recycling agent in emulsion form is introduced, and then compacted.

(iii) Hot in-place recycling

In hot in-place recycling method the existing asphalt surface is heated, scarified to a depth from 20 to 40 mm, scarified material combined with aggregate and/or bituminous binder and/or recycling agent and compacted. New overlay may or may not be provided.

(iv) Full depth reclamation

Here all the bituminous layers and predetermined thickness of underlying material is pulverized, stabilized with additives, and compacted. A surface course is applied over it.

Semi flexible grouted macadam

Grouted Macadam consists of a single sized porous bituminous layer whose voids can be filled with the selected fluid grout or cementations slurry.
The porous bituminous skeleton is designed to achieve a high void content while maintaining a thick bitumen coating on the aggregate particles (Zoorob et al., 2002).
Grouted macadam gives advantages of both flexible and rigid pavements namely,

• Flexibility and absence of joints by use of bitumen,

• High static bearing capacity and wear resistance (as for concrete) by use of cementations grout.

Micro-surfacing

Micro-surfacing is a fast and economical surface treatment technique used for preventive maintenance of bituminous and cement concrete pavements.
Polymer modified emulsion, cold blended with fine graded aggregates, mineral fillers, additives and water, gives the high performing micro-surfacing mixture.
Micro-surfacing is generally used to restore the top wearing surface of pavement as a maintenance measure, thereby extending the pavement life.
Its thickness may be varied to achieve desired objective(s) such as rut-filling, skid resistance improvement, surface sealing, surface texturing, noise reduction, repairing abraded wheel path channels etc (ODOT 2004; Miller 2004).

Design Principle Based

This section discusses about the design principle based innovative applications of road materials. Discussion has been divided into two parts viz.

Structural design considerations, and
Mix design considerations

Optimum pavement design thickness

In Mechanistic-Empirical pavement design, generally sustainability of a pavement structure against fatigue and rutting failures is considered, for which the critical responses are: (a) the tensile strain at the bottom fiber of bituminous layer and (b) the vertical strain at the top of the subgrade. A number of design thickness combinations of bituminous and granular layers are possible which satisfies the above mentioned requirement.

Standard design charts developed by various organizations (Shell 1978; Austroads 1992; Asphalt Institute 1981; IRC:37-2001) are available; these design charts generally provide thickness composition of bituminous and granular layers, depending upon other input parameters viz. temperature, traffic, design life, subgrade strength, material type etc. A designer can choose any suitable granular layer thickness, and, corresponding thickness of bituminous layer can be read from these charts.

Figure 10. Typical pavement design chart

POINT A - Safe from rutting but over safe from fatigue considerations.

POINT B- Safe from rutting but unsafe from fatigue considerations.

POINT C- Safe from fatigue but insafe from rutting considerations.

POINT D- Safe from fatigue but oversafe from rutting considerations.

POINT E - Unsafe from both rutting and fatigue considerations.

Point F- Oversafe from both rutting and fatigue considerations

POINT O- Just safe from both rutting and fatigue considerations.

Figure 10 illustrates a typical design chart. The design chart consists of two curves: fatigue curve and rutting curve. The fatigue curve shown as COD in Figure 10 represents the points, which are just safe from fatigue consideration. Similarly, the rutting curve shown as AOB in Figure 10 represents those points which are just safe from rutting consideration. Figure 10 shows various points like A, B, C, D, etc. They are safe, oversafe or unsafe from fatigue or rutting considerations. The reader can point the cursor on the respective points to know about their status. In the design chart the fatigue curve and the rutting curve intersects at a point (point O in this case) that may be called as structurally balanced design point (Narasimham, et al., 2001). Thickness of pavement layers chosen according to this point will result in a pavement deign which would fail due to fatigue and rutting simultaneously. Similarly, there could be cost optimal point, where bituminous and granular layer thicknesses are selected such that the total cost of materials used is minimized, without compromising with the structural adequacy of the pavement. The cost optimal point may or may not coincide with the structurally optimal point (Narasimham et al. 2001, Das 2004 ).

Perpetual pavement

A perpetual bituminous pavement may be defined as a pavement designed and built to last longer than fifty years without requiring major structural rehabilitation or reconstruction (APA101 2001). This pavement may only require periodic replacement of top wearing surface and recycling of old pavement material (TRL 2001; AA-2 2001).

The concept of full depth bituminous pavement is in vogue from 1980s in USA. Nunn and his associates of Transport Research Laboratory, UK found (Nunn et al., 1997) that thick bituminous pavements tend to show long lasting performance and may require only minor surface repairs. California Department of Transportation in collaboration with University of California, Berkeley (Monismith et al., 2001) first implemented concept of perpetual pavement in a rehabilitation planning project.

In full depth bituminous pavement, the thickness is so designed that the fatigue and rutting strains developed are below the permissible limit (MS-1 1999 ). If the thickness is chosen to be sufficiently large so that the fatigue strain is close to the endurance limit, then the fatigue life becomes very long, and the pavement may be said to have attended 'perpetual life'. A perpetual pavement, in general, is made up of the following layers:

The top wearing surface is designed in such a way that it is water-tight as well as removable and hence replaceable. Stone Matrix Asphalt (SMA) or Open Graded Friction Course (OGFC) are recommended. They also produce less noise due to tyre-pavement interaction.
The intermediate layer is constituted with good quality aggregates and designed to be strongly resistive to rutting.
The bottom part is made resistant to fatigue cracking by making it rich in bitumen and choosing a gradation that has less voids.

Figure 11 Layer composition of a perpetual pavement.

Figure-11 schematically represents the layer composition of a typical perpetual pavement.

A perpetual pavement is a full depth bituminous pavement in most of the cases. The principles based on which it is designed (mix design and structural thickness design) are the following:

The pavement layers are chosen in such a way that they are rut resistive. The pavement is chosen to be adequately thick such that the vertical subgrade strain is low. Since subgrade contributes to the major part of rutting, low vertical subgrade strain would cause low level of rutting.
The wearing surface should be adequately water-proof. The surface should be so designed that it can be repaired or recycled and the whole pavement will not require any major reconstruction (AA-2 2001).
The thickness of the bituminous layer is chosen in such a way that the horizontal tensile strain (ε_t) developed is less than the endurance limit (refer Figure-12) of the bituminous mix, hence its laboratory fatigue life (N) becomes infinity (AA2-2001, Nunn et al. 1997). It is justifiable to design the pavement as 'bottom rich' (refer to next section), which shifts the endurance limit to higher level.
The temperature gradient tends to be steeper towards the surface of the pavement (TRL 2001,Newcomb 2001) as shown schematically in Figure-12. Therefore the bituminous mixes with temperature susceptible binder should be avoided as surface course. Use of modified binder could be helpful in this regard.

Figure 12 Idealized diagram of fatigue characteristics of bituminous mixes.

Rich bottom bituminous pavement

Increased binder content above the optimum content can appreciably enhance the fatigue life.

Higher bitumen content increases the thickness of the binder film between aggregates resulting in lower stress in the binder film, and thus the fatigue life is improved (Sousa et al., 1998; Harvey et al., 1996).

However, with increased amount of binder content, the bituminous mix tends to be softer and thereby its stiffness modulus value may fall.

A mix designer's objective would be to achieve both high stiffness and high fatigue life.

This mutually contradictory situation can be handled by using a bituminous pavement layer where it is made richer in binder content towards the bottom layer(s).

Since fatigue cracks start from bottom of bituminous layer, higher bitumen content helps to give greater restraint against fatigue cracking.

This concept has been termed as 'rich bottom pavement' (Monismith et al., 2001; Harvey et al., 1997; Harvey and Tsai 1996).

Figures 13 and 14 provide two such options of achieving this condition. In Figure-13, quantity of bitumen is used more towards the bottom of the layer. In Figure-14, two different bituminous mixes are used in two layers. Out of three possible alternatives, alternative-II turns out to be the best alternative.

Figure 13 Rich bottom pavement

Figure 14 Two grades of bitumen used in two layers

Inverted pavements

Inverted pavement system, or inverted base, is a high depth pavement whose supporting layers are thicker and stiffer than top layers.
The system consists of a thin bituminous concrete (BC) layer provided on top of a graded aggregate base (GAB) layer. A Portland cement-treated stiff base layer is provided at the bottom.
This arrangement causes the critical stress/strain plane to be located at the interface of the BC and GAB layers. Thus only the top portion of the inverted pavement structure absorbs the traffic loads as compared to conventional design where thick sections are required for load distribution.
Research by South African Roads Board (SARB 2004) and Georgia Department of Transportation, has shown that an inverted base provides enough structural performance to support traffic loadings up to 100 million Equivalent Single-Axle Loads (ESAL s) with a maximum two inch bitumen riding course (Halsted, 2002). According to SARB, this type of system proves to be more cost effective for construction of long lasting pavements.

Bituminous pavement with cemented base

The cemented bases are derived from aggregates mixed with some binding material. Since it is bounded layer, it also has some fatigue life.
Thus, unlike the unbound granular base, the cemented base layer contributes to some fatigue life, which may give rise to comparative reduction of design thickness of bituminous layer (Das and Pandey 1998).
The stiffness modulus of cemented layer is generally found to be much higher than granular sub-base; however, due to shrinkage cracks, the stiffness modulus falls rapidly.
This change in stiffness values at different stages of the design life has been schematically shown in Figure-15(a) and Figure-15(b) presents a typical design chart for design of bituminous pavement with cemented base made up of lime-soil mixture.


15 (a) Change of elastic modulus of cemented bases at different phases.	15 (b) A typical design chart of bituminous pavement with cemented base (LS º lime soil)

Mix design considerations

Non-standard gradation

The fatigue life of the mix can be increased by increasing the bitumen content.

But, Voids in Mineral Aggregates (VMA), being fixed for a given gradation and compaction level, increase in bitumen content will result in less Air Voids (VA), which is undesirable for a mix.

However one can deviate from the specified gradation in order to come up with a new gradation, which possibly can give rise to better fatigue performance, yet without compromising with the VMA and Marshall-stability requirements.

Stone matrix asphalt

Stone matrix asphalt (SMA) is a gap-graded bituminous mix with high percentage of coarse aggregates with high bitumen content. Gap gradation aims at maximizing stone-to-stone contact. This gives a structurally strong mix due to efficient load distribution through the stone-matrix skeleton. The drawback of this method is the absence of medium sized aggregates due to gap gradation. This may arise possibility of drain-down of low-grade penetration bitumen through the stone matrix. To check this possibility, modifiers, such as cellulose fibers, are used to hold the bitumen in place (Better Roads 2003; GDOT 1995; Decoene et al., 1990).

Porous pavement

Porous pavement is a special type of pavement which allows surface water to pass through it, thereby keeping the road surface water-free, as well as providing drainage outlet to storm water.
Porous pavement may be effectively used in light traffic areas like parking areas, airport taxiway and runway shoulders, footpaths, playgrounds etc. provided that the subsoil drainage, groundwater level and topography of the area is suitable (Michele, 2003; USEPA 1999; DEQ 1992).
Pavement structure consists of a top porous bituminous layer placed over a filter layer below which a highly permeable open-graded stone layer (known as reservoir course).
A geotextile layer is placed at the bottom to screen off fine soil particles. Porous bituminous layer consists of gap-graded aggregates (lower percentage fines), held together by a fiber-bitumen blend, giving a matrix structure which allows movement of water through its fine voids.
Besides load bearing, the reservoir course stores the runoff water (in the void spaces in aggregate layers) until it can infiltrate into the soil beneath.
Porous pavement has been found (RPL 2001) to be quite effective in reducing noise levels, splash and spray during rains, and aquaplaning tendency thereby improving the wet skid resistance.

CLOSING REMARKS

Certain standard methods are followed for road design and construction. They are modified from time-to-time to match with the technological advancements. Certain modifications in the mix design or structural design can give rise to substantial economy in terms of the longevity of the pavement or the cost of the material concerned.

Cement is manufactured by heating a mixture of limestone, iron ore, gypsum, clay and other ingredients. Cement concrete is a mixture of coarse aggregates, fine aggregates, cement and water, in suitable proportions. Through mix design, suitable proportions of the ingredients of concrete are estimated considering strength, workability, durability and economics. Workability test and air-content test are the tests generally conducted on fresh concrete. Compressive strength, tensile strength, modulus of rupture, elastic modulus, Poisson's ratio, creep and shrinkage, durability, thermal expansion coefficient etc are the tests conducted on hardened concrete.

Various modifications and innovatory applications of pavement materials and pavement design brings in better performance and economy.

Pavemnt analysis and design II

2010-01-28T00:14:00.001-08:00

Analysis and design of concrete pavements

(Thanks to professor Animesh das and Professor Partha Chakroborty.)

(http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT-KANPUR/transport_e/TransportationII) Materials

Objectives

The lectures in this module propose to introduce the modern materials in pavement construction. It discusses about the scope, application potential, evaluation, and performance expectation of the new highway materials. The second part of the lectures focus on the innovative application concepts of the conventional or the modern materials. Usage of modern materials in highway construction and their innovative application is expected to bring economy in terms of material cost as well as better reliability in performance.

Bitumen as a pavement material

The characterization of bitumen and bituminous mix has been discussed in detail in the web-course Transportation Engineering - I

Bitumen is a complex material, its property ranges from viscous liquid to brittle solid. While bitumen shows linear viscoelastic behavior at small strains, the nonlinear behaviour becomes more prominent at large strains (Monismith and Secor 1962, Pagen 1968, Cheung and Cebon 1997). The deformation of bitumen is loading rate and temperature dependent (Van der Poel, 1955, Deshpande and Cebon 1997).

The bituminous mix is manufactured by mixing bitumen and aggregates of specified size distribution at some specified elevated temperature. Then, the mix is transported to the site, laid and subsequently compacted to pack the aggregate particles together. During the compaction process the air voids are brought down to its desired level. The compacted mix, thus, achieves its strength when it cools down and becomes serviceable asbituminous road . Figure-1 shows a typical cross-section of a bituminous mix sample.

The mechanical behavior of bituminous mix has been studied extensively through various tests, and empirical relationships have been developed for mix design and prediction of the performance of the mix. However, prediction of response of bituminous mix through mechanics based models is a difficult task. Various attempts have been made by the researchers, for example based on, linear viscoelastic principle (Lee and Kim 1998, Kim and Little 2004), elastic visco plastic principle (Uzan 2005), discrete element analysis (Sadd 2004, Abbas et al. 2005) etc., so as to capture the complex mechanical behavior of bituminous mixture.

Cement Concrete as a pavement material
Introduction

Cement concrete is a mixture of coarse aggregates, fine aggregates, cement and water in suitable proportions. Sometimes admixtures are also added to achieve specific behaviour/ property of the material. The components of cement concrete are briefly introduced in the following.

Components of cement concrete

Aggregates

Aggregates are naturally available pieces of rocks. The aggregates could be igneous, sedimentary and metamorphic type depending on its origin. Figure-1 shows a photograph of aggregates being manufactured from a stone query. The details about the physical properties of aggregates have discussed in the web-course on Transportation Engineering-1 .

Cement

Cement is manufactured by heating a mixture of limestone, iron ore, gypsum, clay and other ingredients. Two processes, namely dry process and wet process are followed while manufacturing cement. In the dry process, the raw materials are mixed in dry state, whereas in the wet process raw materials are mixed in presence of water to form slurry . After pre-heating, the raw material is passed through rotating kiln inclined with a small angle with the horizontal line. The kiln is progressively hotter towards its lower end, where the raw material gets molten. From this clinkers are formed when cooled, and after grinding the clinkers, cement is produced. An animated description of the whole process can be obtained elsewhere (cement.org 2006).

The Ordinary Portland Cement (OPC) is the most popular, all-purpose cement. There are various other types of cements (for example, natural cement, Portland pozzolanic cement, high alumina cement, expansive cement, quick setting cement, high performance cement, sulphate resistant cement, white cement etc.) and are manufactured to serve specialized purposes. For concrete pavement construction, OPC is most commonly used.

Water

Water participates in the hydration process; also it provides desirable level of workability. About one third of the water added is utilized in the hydration process, rest forms the pores of concrete, and thereby developing porosity to the concrete. Excess porosity reduces strength of the concrete, and however presence of porosity is good for the situations where there is a freeze-thaw problem.

Admixtures

Admixtures are generally of two types, chemical admixture, and mineral admixture. Air entrainer, retarder ,accelerators are examples chemical admixture, and, fly ash, silica fume are the examples of mineral admixtures. One of the important concrete admixtures used in pavement construction is the air-entraining admixture. Air entraining admixtures are derived from natural wood resins, fats, sulfonated hydrocarbons and oils etc (Wright and Dixon 2004). Air-entraining admixtures provide durability against freeze-thaw situation.Plasticizers may be used for concrete pavement construction purposes which maintain workability without having increased the water-cement ratio. Calcium chloride is also used sometimes, as accelerating agent, which renders an early strength of concrete.

Mix design

Through mix design, suitable proportions of the ingredients (coarse aggregates, fine aggregates, cement, water and admixture, if any) are estimated, keeping in view the strength, workability, durability and economic considerations. These proportions are achieved through iterative experimental procedure in the laboratory. There are number of methods for mix design of cement concrete, and a detailed discussion can be obtained elsewhere (Neville and Brooks 1999).

Water-cement ratio is an important consideration in the mix design process. As water cement ratio is increased in concrete, the durability and strength decreases, however, the workability enhances. Depending on the type of construction, workability requirements are different.

For large scale production of cement concrete, the proportioning operation is performed in the batch mixing plant . Figure 3 shows a photograph of a typical concrete batch mixing plant.

Properties of fresh concrete

Ideally a fresh concrete should be workable, should not segregate or bleed during construction. Constituent properties, their proportions, aggregate shape and sizes, temperature affect the performance of fresh mix. The tests that are conducted on fresh concrete include workability test and air-content test. Some of tests through which workability of can be estimated are Kelly ball penetration test, slump test, compacting factor test, Vee bee test and flow table test etc.

Curing of concrete

Presence of adequate amount of moisture, at some requisite temperature and for a suitable period of time, is necessary to complete the hydration process of cement. This process is called curing. The curing conditions significantly affect the final strength achieved by the concrete. For pavement construction, only in-situ curing methods are applicable. Curing compounds are sometimes applied to retain the moisture against evaporation. For final curing of concrete pavements continuous ponding or moistened hessain/ gunny bags are used .

Properties of hardened concrete

Tests are conducted on hardened concrete to estimate properties like, compressive strength, tensile strength, modulus of rupture, elastic modulus, Poisson's ratio, creep and shrinkage performance, durability, thermal expansion coefficient etc. These parameters are of functions of aggregate type, shape and size, type and quantity of cement and admixtures incorporated, water cement ratio, curing, age etc.

Compressive strength of concrete is the failure compressive stress on cubical or cylindrical samples of concrete. Compressive strength of concrete is related to the combined effect of temperature and time, a parameter called maturity. Maturity of concrete is calculated as the time of curing (in hours), multiplied by the temperature, (in degrees) above some specified reference temperature. Various empirical relationships are suggested to obtain the various strength parameters of concrete (elastic modulus, tensile strength, bending strength etc.) from the compressive strength of concrete.

Direct tension test on concrete is performed by applying tension to the cylindrical or dumble shaped samples of concrete. Indirect tension is applied to concrete samples by split cylinder test.

Modulus of rupture of concrete is estimated by measuring the maximum bending stress on concrete beam subjected to pure bending in static condition.

Fatigue test is generally performed subjecting the concrete beams with repetitive flexural loading. The more is the stress ratio (defined as the ratio between the bending stress applied to the modulus of rupture) the less is the fatigue life. The empirically derived fatigue equation by PCA (1974) is the following:

(1)

and

(2)

Where, N_f is the number of load applications to failure, SR is the stress ratio with reference to 90 days modulus of rupture.
The equation suggested by AASHTO (1993) is the following:

(3)

Transportation of concrete

The transportation of concrete is to be done in such a way that segregation and premature setting is avoided.Wheel barrow, truck mixer, dumper truck, belt conveyor, pipe-line etc. are the various ways concrete is transported to the construction site. Figure 4 shows a typical truck concrete mixer.

A typical truck concrete mixer

Introduction

Road is a costly infrastructure to build and maintain. Thus there is always a need ofr development of (i) new road materials as well as (ii) innovative applications of existing/new materials. These issues are discussed here.

EMERGING ROAD MATERIALS

Modification of Existing Materials

Existing materials may require modifications so as to

improve engineering properties of material
satisfy general specification requirement of locally available material which in turn would prove to be cost effective
meet the demand of special purpose materials having specific properties. Example: high or low permeability, enhanced shear strength etc

These have been discussed further under two sections as,

binder (bitumen) modification
aggregate modification

Binder (bitumen) modification

Binder (bitumen) modification is done with the help of additives which may or may not react chemically with bitumen. Table 1 presents a partial list of various types of binder modifiers, their purpose and examples. Binder modification results improvement of one or more properties of the binder (and hence the mix) viz. fatigue resistance, stiffness modulus, rutting resistance, stripping potential, temperature susceptibility, oxidation potential etc.

Table 1. Some examples of binder (bitumen) modifiers

(RILEM 1998; ETM 1999; Asphalt Handbook 2000; Widyatmoko 2002, SEAM 2004 )

	Purpose	Examples
Polymers
Fillers	to improve bitumen durability and check rutting	Lime, carbon black, fly ash
Anti-oxidants	to check oxidative hardening	Zinc anti-oxidants, lead anti-oxidant, phenolics, amines
Anti-stripping additives	to achieve better adhesion of bitumen to aggregates	Organic compounds (like arnines, andamides)
Extenders	to act as bitumen substitute and to improve fatigue resistance	Lignin, sulphur
Others	-	Shale oil, gilsonite, silicon, inorganic fibers, Trinidad lake asphalt (TLA)
Non Polymers
Fibers	to reduce viscosity, as filler material,	Polyester fibers, Polypropylene fibers
Plastics -Thermoplastics -Thermosets	to increase the viscosity and stiffness of bitumen at normal service temperatures without compromising with fatigue performance to obtain insoluble, infusible material that do not flow on heating	Polyethylene (PE), Polypropylene (PP), Polyvinyl chloride (PVC), Polystyrene (PS) Ethylene vinyl acetate (EVA). Epoxy resins
3. Elastomers - Natural - Synthetic - Reclaimed rubbers	to reduce temperature susceptibility and temperature distresses, age-hardening, bleeding and binder-aggregate stripping.	Rubber Styrene-butadiene copolymer (SBR), Styrene-butadiene-styrene copolymer (SBS), Ethylene-propylene-diene terpolymer (EPDM), Isobutene-isoprene copolymer (IIR)

For conventional binders, it is generally observed that the mixes with high stiffness modulus (E)show low fatigue life, and vice versa. However, for an economical pavement design, both high elastic modulus as well as high fatigue life is desirable. Through binder modification, this particular disadvantage can be avoided. Figure 5 presents this concept schematically.

As can be seen in Figure 5, for mixes with ordinary binder, although elastic modulus E value is higher initially at low temperatures, at high E value the fatigue performance generally becomes poor. On the other hand, at high temperature the E value becomes too low and the mix becomes soft. The bituminous mixes with modified binder does not allow the mix to be too hard (high E value) or too soft (low E value) at low and high temperatures respectively. Thus the stiffness versus temperature curve takes a 'S-shape' as shown in Figure 5.

Aggregate modification

The marginal or poor quality aggregates can be improved by using some cementing material such as cement, lime, pozzolanic substance etc.
The proportions of the cementing material and other ingredients (like water) can be suitably estimated in the laboratory

DEVELOPMENT OF ALTERNATIVE MATERIALS

Given the fact that good quality aggregates are depleting and cost of material extraction is increasing, researchers are looking for suitable alternative materials.
The tests and specifications, which are applicable for conventional materials, may be inappropriate for evaluation of non-conventional materials ( i.e. alternative materials).
This is because the material properties, for example, particle sizes, grading and chemical structure, may differ substantially from those of the conventional materials.
Thus, for an appropriate assessment of these materials, new tests are to be devised and new acceptability criteria are to be formed.
However, with the advent of performance-based tests, it is expected that the performances of the conventional as well as new materials can be tested on a same set-up and be compared.

Industrial and Domestic Wastes

Industrial and domestic waste products provide a prospective source of alternative materials.
These materials are cheaply available.
Also, their use in road construction provides an efficient solution to the associated problems of pollution and disposal of these wastes.

Table 2 presents a partial list of industrial waste materials that can be used in road construction. Table 3summarizes the advantages and disadvantages of using specific industrial wastes in road construction.

Table 2. Industrial waste product usage in road construction (TFHRC 2004; Hamad et al., 2003;Hawkins et al., 2003; Mroueh et al., 2002; Okagbue et al. , 1999; Sherwood 1995; Javed et al., 1994)

Waste product	Source	Possible usage
Fly ash	Thermal power station	Bulk fill, filler in bituminous mix, artificial aggregates
Blast furnace slag	Steel industry	Base/ Sub-base material, Binder in soil stabilization (ground slag)
Construction and demolition waste	Construction industry	Base/ Sub-base material, bulk-fill, recycling
Colliery spoil	Coal mining	Bulk-fill
Spent oil shale	Petrochemical industry	Bulk-fill
Foundry sands	Foundry industry	Bulk-fill, filler for concrete, crack-relief layer
Mill tailings	Mineral processing industry	Granular base/sub-base, aggregates in bituminous mix, bulk fill
Cement kiln dust	Cement industry	Stabilization of base, binder in bituminous mix
Used engine oil	Automobile industry	Air entraining of concrete
Marble dust	Marble industry	Filler in bituminous mix
Waste tyres	Automobile industry	Rubber modfied bitumen, aggregate
Glass waste	Glass industry	Glass-fibre reinforcement, bulk fill
Nonferrous slags	Mineral processing industry	Bulk-fill, aggregates in bituminous mix
China clay	Bricks and tile industry	Bulk-fill, aggregates in bituminous mix

Table 3. Suitability of using industrial waste products in road construction

(TFHRC 2004; Hamad et al., 2003; Hawk ins et al., 2003; Nunes et al. 1996; Sherwood 1995; Javed et al., 1994)

Material	Advantages	Disadvantages
Fly ash	Lightweight, used as binder in stabilized base/ sub-base due to pozzolanic properties	Lack of homogeneity, presence of sulphates, slow strength development
Metallic slag - Steel slag - Nonferrous slag	Higher skid resistance Light weight ( phosphorus slag)	Unsuitable for concrete and fill work beneath slabs. May show inconsistent properties
Construction and demolition waste	More strength, can be used as aggregates granular base	May show inconsistent properties
Blast furnace slag	Used in production of cement, granular fill	Ground water pollution due to leachate formation, used as unbound aggregates
Colliery spoil	-	Combustion of unburnt coal, sulphate attack in case of concrete roads
Spent oil shale	-	Burning of combustible materials
Foundry sands	Substitute for fine aggregate in bituminous mixes	Presence of heavy metals in non ferrous foundry origin, less affinity to bitumen
Mill tailings	Some are pozzolanic in nature	Presence of poisonous materials (e.g., cyanide from gold extraction)
Cement kiln dust	Hardens when exposed to moisture, can be used in soil stabilization	Corrosion of metals (used in concrete roads) in contact because of significant alkali percentage
Used engine oil	Good air entertainer, can be used in concrete works	Requires well organized used oil collection system
Rubber tires	Enhances fatigue life	Requires special techniques for fine grinding and mixing with bitumen, sometimes segregation occurs

The incenerated municipal soild waste (MSW), after further processing, can be used as fines in bituminous mixes. Processing is done to remove ferrous and nonferrous metals and to achieve the required particle size gradation. Due to the presence of larger fraction of fines, MSW ash is primarily used as fine aggregate. It is also used as a fill material in road construction. The ash can also be stabilized with portland cement or lime to produce stabilized base/sub-base material (TFHRC 2004).

For conventional road materials, a number of tests are conducted and their acceptability is decided based on the test results and the specifications. This ensures the desirable level of performance of the chosen material, in terms of its permeability, volume stability, strength, hardness, toughness, fatigue, durability, shape,viscosity, specific gravity, purity, safety, temperature susceptibility etc., whichever are applicable.

There are a large number tests suggested by various guidelines/ specifications. Figure-6 presents a suggested flow chart to evaluate the suitability of industrial waste for potential usage in highway construction

Health and safety considerations should be given due importance handing industrial waste materials ( Mroueh and Wahlström 2002, Nunes et al. 1996 ).

1.2.2. Other alternative materials

Steel slag aggregate is a good example of synthetic aggregates obtained from by-products of industrial processes. It has good binding properties with bitumen due to its high calcium oxide content (NatSteel 1993). The angular shape of the aggregates helps to form strong interlocking structure. Road paving with steel slag aggregate show

good skid resistance
mechanical strength able to withstand heavy traffic and surface wearing.

Also, many industrial and other waste products like fly-ash, cement kiln dust, incenerated refuse etc. have been successfully used to produce synthetic aggregates.

Mixing bitumen with rubber (natural or crumb form) sometimes poses difficulty. As an alternative approach, tiny crumb rubber pieces can be mixed with aggregates - known as dry-process. Research shows improved fatigue performance for this kind of materials (Sibal et al. 2000), also, this process does not require any modification to the existing batch mixing plant.

Pavement deisgn and analysis

2010-01-28T00:10:00.000-08:00

Pavement design

(Thanks to professor Animesh das and Professor Partha Chakroborty.)

(http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT-KANPUR/transport_e/TransportationII)

The objective of this lecture module is to introduce the basic concepts of analysis and design of pavement structure.

Also a discussion has been placed as past, present and future perspective of pavement analysis and design.

Types of pavement structures

Pavements, in general, can be classified in two major categories: concrete pavement and bituminous pavement.
Concrete pavements are generally called rigid pavements and bituminous pavements as flexible pavements.
There could be some other types of pavements which are neither rigid, nor flexible, for example, block pavement, composite pavement.

A Pavement is a multi-layered structure. The layers are placed horizontal one over other. In general, the strengths of the layers decrease from top towards bottom except some special situation like inverted pavement. The terminologies used to identify various layers of bituminous and concrete pavements are identified in Figs. 1and 2

Fig. 1 cross section of a typical bituminous pavement (Chakroborty and Das 2003)

Fig. 2 cross section of a typical rigid pavement (Chakroborty and Das 2003)

Bituminous pavement

The subgrade is a compacted soil layer.
The base and sub-base course could be made up of bound or unbound granular layer. As per Indian specifications (MORT&H 2001), some examples of base or sub-base layers are: Granular sub-base (GSB), Water Bound Macadam (WBM), Wet Mix Macadam (WMM) etc.
The binder course is made up bituminous material. As per Indian specifications (MORT&H 2001), some examples of binder course are: Bituminous Macadam (BM), Dense Bituminous Macadam (DBM) etc.
The wearing course is the top bituminous layer which is comes in contact to the vehicle tyre. Wearing course provides impermeability to the pavement surface against water percolation (Chakroborty and Das 2003). The binder course and wearing course together are called bituminous surfacing.

Concrete pavement

Concrete pavement is, in general, consists of three layers, subgrade, base layer and the concrete slab.
Generally bound base layers are used for concrete pavement construction. As per Indian specification, some example of such base layers are Dry Lean Concrete (DLC), Roller Compacted Concrete (RCC) (IRC:15-2002)
The concrete slab is generally of M40 to M50 grade of concrete as per Indian specifications, and is called as paving quality concrete (PQC) (IRC:15-2002).

Joints in concrete pavement

Fig.3 Location of joints in concrete pavement

Joints are the discontinuities in the concrete pavement slab, and help to release stresses due to temperature variation, subgrade moisture variation, shrinkage of concrete etc.
There are various types of joints in concrete pavement, e.g. contraction joint, construction joint, expansion joint and warping joint. Fig. 3 schematically shows position of various joints. The functions of these joints are as follows:

Contraction joint: Contraction joints are provided along the transverse direction to take care of the contraction of concrete slab due to its natural shrinkage.
Construction joint: Construction joints are provided whenever the construction work stops temporarily. The joint direction could be either along the transverse or longitudinal direction.
Expansion joint: Expansion joints are provided along the transverse direction to allow movement (expansion/ contraction) of the concrete slab due to temperature and subgrade moisture variation.
Warping joint: Warping joints are provided along the longitudinal direction to prevent warping of the concrete slab due to temperature and subgrade moisture variation.

These discontinuities (joints) could be extended to the full or partial depth of the slab. Sometimes iron bars are provided across the joints, the iron bars along the longitudinal joints are called tie bars and along the transverse joints are called dowel bars.

Pavement analysis and design: historical perspective

The past pavement design approaches were mostly empirical in nature and were based on experience.

CBR method of pavement design is one of the earlier pavement design approach developed during 1928-29 (Ullidtz 1986). In this method the thickness design charts are developed (based on observation of number of sections), with reference to the sub grade CBR value for the most critical moisture condition. In 1940 this method was adopted by the U.S. Corps of Engineers for design of airfield pavements (Horonjeff and Mckelvey 1983). It is interesting to note that the design initially did not involve traffic as a parameter, which was introduced later as a correction factor. The method was further improved by considering the CBR values of the individual layers and thereby individual layer thicknesses are obtained. In some other approach, Hveem resistance value of pavement materials is used instead of CBR value.
Another pavement design approach considers aspect of bearing capacity of the individual layers, and the design is finalized in such a way that the bearing stress does not exceed the bearing capacity of the individual layers. This method was first proposed by Barbar in 1946, and is still in use (TRH4 1996, deBruin et al. 2002), however this method does not seem to account for traffic repetitions.
Another approach recommends limiting recoverable deflection as the criterion for pavement design (Huang 1993). Failure theories suggest that the failure of a structure is due to excess stress or strain, thus, deflection may not be attributed as basic pavement design criteria.

Pavement analysis and design : current perspective

Present practice of pavement design involves considerations of three aspects: structural design, functional design and drainage design and they are explained briefly in the following:

Structural design

In structural design the stresses due traffic loading and temperature are estimated, and the thickness of the pavement is designed in such a way that these developed stresses/ strains are below the allowable values. The current practice of pavement design, more popularly, is known as Mechanistic-Empirical pavement design and is followed by a number of organizations around the world (Asphalt Institute 1999, Shell 1978, Austroads 1992, NCHRP 2005, IRC 2001). It is mechanistic pavement design because it uses stress/ strain of a pavement structure using mechanics based principle, and, as well, it is empirical because the expected life for a given stress/ strain level is estimated from empirical relationships obtained from laboratory or field performance studies. The pavement design approach is not governed by the maximum amount of load that the pavement can sustain, rather, it estimates the number of standard load repetitions that can cause failure.

Estimation of pavement stress/strain

Stress/ strain due to load

For pavement design purpose, the stress/ strain value of a pavement structure is obtained from structural analysis of the pavement (Ioannides et al. 1998). The stress/ strain values at any point of a pavement structure can be estimated when the elastic moduli, Poisson's ratio and the thicknesses of the individual layers are known. The strain values can also measured using strain gauges.
Any analysis procedure involves idealization regarding the structure; similarly, measuring strain involves measurement errors - hence the true value of stress/ strain is never known.
A concrete pavement slab, in general, has finite dimensions, and thus the analysis approach of concrete pavement becomes different than the analysis of bituminous pavement. For bituminous pavement, in general, the pavement is assumed as infinite in both the directions, whereas for concrete pavement, in general, it is analysed as discrete slabs connected by joints. The concrete pavement is also assumed to have bending moment carrying capacity, whereas flexible pavement is assumed to have no moment carrying capacity.

Stress/ strain due to temperature

The change of temperature causes the pavement to expand or contract. The restriction of free movement causes temperature stresses.
There exists temperature variation across the depth of the pavement - this causes warping stresses.
The temperature stress varies across the corner, interior and edge of the concrete slab, also at different times of the day. The most critical combination of load and temperature stress is used as design criteria.
The temperature stress in bituminous pavement is insignificant. Hence, temperatire stress, is not considered in pavement design. However, temperature affects the elastic modulus of the bituminous layer, which needs to be duly considered in pavement design.

Estimation of layer thicknesses

The thickness of the pavement is adjusted in such a way that the stress/ strain developed is less than the allowable values obtained from past performance information.
The two major modes of structural failure of pavement are fatigue and rutting.

Fatigue: Traffic applies repetitive load to the pavement surface, and the cracks start from bottom the bound layer/ slab and propagate upwards. When the extent of surface cracks reaches a predefined level, the pavement is said to have failed due to flexural fatigue.

· Conventionally, for design of concrete pavement stress is used as parameter, and for design of bituminous pavement strain is used as parameter.

Rutting: Rutting is the accumulation of permanent deformation. This is the manifestation of gradual densification of pavement

The vertical strains on the pavement layers, mainly the vertical strain on the subgrade is assumed to be governing factor for rutting failure.
The rutting issue is not considered for concrete pavement design, because it does not have any permanent deformation.

The fatigue/ rutting equations are developed from field or laboratory studies, where fatigue / rutting lives are obtained with respect to respective stress/ strain for fatigue/ rutting. For a given design life, thus, allowable fatigue and rutting stress/ strains can be estimated using the fatigue/ rutting equations.
The various other types of pavement failures could be shrinkage, thermal fatigue, top down cracking (for bituminous pavement) etc.

layers, and shear displacement of the subgrade.

Design of joints

The spacing of the contraction joint is estimated from the shrinkage potential of concrete. The spacing of the expansion joint is estimated from the coefficient of thermal expansion of concrete, maximum change of temperature and the acceptable joint gap. Since, the concrete is good in compression, the experience over last few decades indicates that concrete pavement can be constructed without any provision of expansion joint (ACPA 1992). The dowel bars are designed by assuming that they participate in the load transfer, when the vehicle moves from one slab to other. The tie bars are designed in such way that they have enough strength to tie the two adjacent slabs. The design of dowel bar and tie bar is discussed in detail later.

Functional design

The functional pavement design involves considerations of skid resistance, roughness, surface distresses, reflectivity of pavement surface etc. The functional pavement design considers mainly the surface features of a pavement.

Drainage design

A road needs to be designed in such a way that the rain/ snow precipitation is drained off the pavement and its surroundings. A suitable surface drainage system for the pavement is designed for this purpose. Some water, however, will percolate into the pavement from its top surface and needs to be taken out of the pavement - this is done by providing an internal drainage system to the pavement. Water will also try to enter into the pavement from bottom due to capillary rise or due to rise in water table. A suitably designed sub-surface drainage system tries to avoid such a problem.

Pavement analysis and design: future perspective

Mix design, quality control, construction method and pavement design together determines the performance and longevity of a pavement. The future pavement design is expected to take an integrated design approach considering all these issues together.
The parameters associated with pavement design are stochastic in nature. Thus, the two pavement designs (designed deterministically) having same design traffic may have different levels of reliabilities of survival. Thus, reliability issues of pavement design are gradually becoming important considerations (NCHRP 2005).
A pavement designer essentially looks for the most economical design, yet considering the structural, functional, and drainage design requirement. The future pavement design practice is expected to consider the cost optimality over the entire life cycle of the pavement (Abaza and Abu-Eisheh 2003).

The present module highlights the basics of analysis and design of bituminous and concrete pavements. Pavements are analysed as layered horizontal structure with given elastic module and Poisson's ratio. Concrete pavement, in general, is made up of discrete slabs - therefore, it has joints both in longitudinal and transverse direction. A pavement is designed from structural, functional and drainage considerations. Fatigue and rutting are two major modes of structural failure of pavements. For concrete pavement design, temperature stresses are also considered along with stresses due to load. A pavement designer does not design a pavement for the ultimate load the pavement can carry, rather, the number of repetitions that the pavement can sustain

India's first 84-m high Roller Compacted Concrete dam

2010-01-26T21:10:00.000-08:00

The Irrigation Department, Government of Maharashtra, is constructing the first dam in India using Roller Compacted Concrete (RCC) technology with a high percentage of fly ash. The work on the project, under the Ghatghar Pumped Storage Scheme, has commenced on the river Pravara, near Nashik, and is due for completion by December 2004.

Three dams - Upper Dam, Saddle Dam-1 and Lower Dam - will be constructed under this scheme with RCC technology by using dry fly ash with cement. The project includes a major dam with a height of 84 metres. The fly ash will be available from the thermal power station at Nashik.
The main benefit of RCC is efficient and speedy construction: the project will be completed in just two years; otherwise about 10 years if conventional concrete is used to construct these dams. The other advantages are higher substitution (up to 70 per cent) of cement by fly ash and reduced heat of hydration, consequently lesser expenses on cooling infrastructure.
The Ghatghar Pumped Storage Scheme provides for the installation of two 125-mw reversible pump turbine and generator motor units in an underground power house. The upper portion of this scheme is located near village Ghatghar, Akole taluka, Ahmednagar district, and its lower portion is near village Chonde, Shahapur taluka, Thane district.

Thanks to

;

http://www.projectsmonitor.com/detailnews.asp?newsid=7197

2010-01-26T20:55:00.000-08:00

Roller-compacted concrete

From Wikipedia, the free encyclopedia

Roller-Compacted Concrete (RCC) is a special blend of concrete that has the same ingredients as conventional concrete but in different ratios. It has cement, water, and aggregates, but RCC is much drier and essentially has no slump. RCC is placed in a manner similar to paving, often by dump trucks or conveyors, spread by bulldozers or special modified asphalt pavers. After placement it is compacted by vibratory rollers.

RCC is typically used for concrete pavement, but it is increasingly used to build concrete dams because the low cement content causes less heat to be generated while curing than do conventional massive concrete pours. For dam applications, RCC sections are built lift-by-lift in successive horizontal layers resulting in a downstream slope that resembles a concrete staircase. Once a layer is placed, it can immediately support the earth-moving equipment to place the next layer. After RCC is deposited on the lift surface, small dozers typically spread it in one-foot-thick layers (300mm).

The first RCC dam built in the USA was the Willow Creek Dam on Willow Creek, a tributary in Oregon of the Columbia River. It was constructed by the Army Corps of Engineers between November 1981 and February 1983. Construction proceeded well, within a fast schedule and under budget (estimated $50 million, actual $35 million). On filling though, it was found that the leakage rate between the compacted layers was unusually high. Remedial grouting at a further cost of $2 million was required to reduce this. Concern over the dam's safety has continued, especially as Heppner had already suffered a dam collapse and fatal flooding with about 250 deaths in 1903. Within a few years of construction, problems were noted with stratification of the water and anoxic decomposition producing hydrogen sulfide. Concerns were expressed that this could in turn give rise to sulfuric acid, and thus damage to the concrete. Controversy continued for some years and the handling of the problem itself has been criticized. In 2004 an aeration plant was installed to address the root cause, as had been called for 18 years earlier.

All about Road

2010-01-23T01:13:00.001-08:00

Road
From Wikipedia, the free encyclopedia

The St. Gotthard Pass road withhairpin turns in the Swiss Alps,Switzerland

A road is an identifiable route, way or path between places.[1] Roads are typically smoothed, paved, or otherwise prepared to allow easy travel;[2] though they need not be, and historically many roads were simply recognizable routes without any formal construction or maintenance.

The term was also commonly used to refer to roadsteads, waterways that lent themselves to use by shipping. Notable examples being Hampton Roads, in Virginia, the seaway Barry Roads in the Bristol Channel and Castle Roads, in Bermuda (also formerly in Virginia).

For purposes of international comparison, the OECD has defined a road to be:

Definition:

Line of communication (travelled way) using a stabilized base other than rails or air strips open to public traffic, primarily for the use of road motor vehicles running on their own wheels.

Context:

Included are bridges, tunnels, supporting structures, junctions, crossings and interchanges. Toll roads are also included. Excluded are dedicated cycle paths.

In urban areas roads may diverge through a city or village and be named as streets, serving a dual function as urban space easement and route. Economics and society depend heavily on efficient roads. In the European Union (EU) 44% of all goods are moved by trucks over roads and 85% of all persons are transported by cars, buses or coaches on roads.

Interstate 80, the second-longest U.S. Interstate highway, runs fromCalifornia to New Jersey

Castle Roads, in Bermuda. An example of the maritime application of the word roads.

The United States has the largest network of roadways of any country with 6,430,366 kilometers (3,995,644 mi) (2005). The People's Republic of China is second with 3,583,715 kilometers (2,226,817 mi) of roadway (2007) See List of countries by road network size. The Republic of India has the third largest road system in the world with 3,383,344 kilometers (2,102,312 mi) (2002). When looking only at expressways the National Trunk Highway System (NTHS) in People's Republic of China has a total length of 45,000 kilometers (28,000 mi) at the end of 2006, and 60,300 km at the end of 2008, second only to the United States with 90,000 kilometers (56,000 mi) in 2005.

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Historical road construction

A Greek street from the 3rd to 4th century BC in Velia, Italy. The Porta Rosa was the main street ofElea. It is paved with limestone blocks, with a gutter for the drainage of rain water.

Main article: History of road transport

That the first pathways were the trails made by animals has not been universally accepted, arguing that animals do not follow constant paths. Others believe that some roads originated from following animal trails. The Icknield Way is given as an example of this type of road origination, where man and animal both selected the same natural line. By about 10,000 BC, rough pathways were used by human travelers.

 Stone paved streets are found in the city of Ur in the Middle East dating back to 4000 BC

 Corduroy roads (log roads) are found dating to 4,000 BC in Glastonbury, England

 The timber track way; Sweet Track causeway in England, is one of the oldest engineered roads discovered and the oldest timber track way discovered in Northern Europe. Built in winter 3807 BC or spring 3806 BC, tree-ring dating (Dendrochronology) enabled very precise dating. It has been claimed to be the oldest road in the world.

 Brick paved streets were used in India as early as 3000 BC

 In 500 BC, Darius I the Great started an extensive road system for Persia (Iran), including the famous Royal Road which was one of the finest highways of its time.[14] The road remained in use after Roman times.

A paved Roman road in Pompeii, Italy.

 In ancient times, transport by river was far easier and faster than transport by road,[13] especially considering the cost of road construction and the difference in carrying capacity between carts and river barges. A hybrid of road transport and ship transport beginning in about 1740 is the horse-drawn boat in which the horse follows a cleared path along the river bank.

 From about 312 BC, the Roman Empire built straight[17] strong stone Roman roads throughout Europe and North Africa, in support of its military campaigns. At its peak the Roman Empire was connected by 29 major roads moving out from Rome and covering 78,000 kilometers or 52,964 Roman miles of paved roads.

 In the 700s AD, many roads were built throughout the Arab Empire. The most sophisticated roads were those of the Baghdad, Iraq, which were paved with tar in the 8th century. Tar was derived from petroleum, accessed from oil fields in the region, through the chemical process of destructive distillation.

 In the 1600s road construction and maintenance in Britain was traditionally done on a local parish basis.[13] This resulted in a poor and variable state of roads. To remedy this, the first of the "Turnpike Trusts" was established around 1706, to build good roads and collect tolls from passing vehicles. Eventually there were approximately 1,100 Trusts in Britain and some 36,800 km of engineered roads. The Rebecca Riots inCarmarthenshire and Rhayader from 1839 to 1844 contributed to a Royal Commission leading to the demise of the system in 1844.

Road transport economics

Main article: Transport economics

A road in Mumbai, India. Most of the roads across the world are built and maintained by the public sector

Transport economics is a branch of economics that deals with the allocation of resources within the transport sector and has strong linkages with civil engineering. Transport economics differs from some other branches of economics in that the assumption of a spaceless, instantaneous economy does not hold. People and goods flow over networks at certain speeds. Demands peak. Advanced ticket purchase is often induced by lower fares. The networks themselves may or may not be competitive. A single trip (the final good from the point-of-view of the consumer) may require bundling the services provided by several firms, agencies and modes.

Although transport systems follow the same supply and demand theory as other industries, the complications of network effects and choices between non-similar goods (e.g. car and bus travel) make estimating the demand for transportation facilities difficult. The development of models to estimate the likely choices between the non-similar goods involved in transport decisions "discrete choice" models led to the development of the important branch of econometrics, and a Nobel Prize for Daniel McFadden.

In transport, demand can be measured in numbers of journeys made or in total distance traveled across all journeys (e.g. passenger-kilometres for public transport or vehicle-kilometres of travel (VKT) for private transport). Supply is considered to be a measure of capacity. The price of the good (travel) is measured using the generalised cost of travel, which includes both money and time expenditure. The effect of increases in supply (capacity) are of particular interest in transport economics (see induced demand), as the potential environmental consequences are significant.

Road building and maintenance is an area of economic activity that remains dominated by the public sector(though often through private contractors). Roads (except those on private property that are not accessible to the general public) are typically paid for by taxes (often raised through levies on fuel), though some public roads, especially freeways are funded by tolls.

Environmental aspects

Air pollution along Pasadena Highway in Los Angeles, United States

Promenade in Florence, Italy

Air pollution

Motor vehicles operating on roads contribute emissions, particularly for congested city street conditions and other low speed circumstances. Of particular concern are particulate emissions from diesel engines. Concentrations of air pollutants and adverse respiratory health effects are greater near the road than at some distance away from the road. Road kicked up by vehicles may trigger allergic reactions.Sand applied to icy roads can be ground up by traffic into fine particulates and contribute to air pollution.

Water pollution

Urban runoff from roads and other impervious surfaces is a major source of water pollution.[26] Rainwater and snowmelt running off of roads tends to pick up gasoline, motor oil, heavy metals, trash and other pollutants. Road runoff is a major source of nickel, copper, zinc, cadmium, lead and polycyclic aromatic hydrocarbons (PAHs), which are created as combustion byproducts of gasoline and other fossil fuels.

De-icing chemicals and sand can run off into roadsides, contaminate groundwater and pollute surface waters. Road salts (primarily chlorides of sodium, calcium or magnesium) can be toxic to sensitive plants and animals. Sand can alter stream bed environments, causing stress for the plants and animals that live there.

Noise pollution

Motor vehicle traffic on roads generates noise pollution especially at higher operating speeds, near intersections and on uphill sections. Therefore, considerable noise health effects are expected from road systems used by large numbers of motor vehicles. Noise mitigation strategies exist to reduce sound levels at nearby sensitive receptors. The idea that road design could be influenced by acoustical engineering considerations first arose about 1973.

Construction

Road construction requires the creation of a continuous right-of-way, overcoming geographic obstacles and having grades low enough to permit vehicle or foot travel. and may be required to meet standards set bylaw or official guidelines. The process is often begun with the removal of earth and rock by digging or blasting, construction of embankments, bridges and tunnels, and removal of vegetation (this may involve deforestation) and followed by the laying of pavement material. A variety of road is employed in road building.

After design, approval, planning, legal and environmental considerations have been addressed alignment of the road is set out by a surveyor. The Radiiand gradient are designed and staked out to best suit the natural ground levels and minimize the amount of cut and fill. Great care is taken to preserve reference Benchmarks .

Roadways are designed and built for primary use by vehicular and pedestrian traffic. Storm drainage and environmental considerations are a major concern. Erosion and sediment controls are constructed to prevent detrimental effects. Drainage lines are laid with sealed joints in the road easement with runoff coefficients and characteristics adequate for the land zoning and storm water system. Drainage systems must be capable of carrying the ultimate design flow from the upstream catchments with approval for the outfall from the appropriate authority to a watercourse, creek, river or the sea for drainage discharge.

A Borrow pit (source for obtaining fill, gravel, and rock) and a water source should be located near or in reasonable distance to the road construction site. Approval from local authorities may be required to draw water or for working (crushing and screening) of materials for construction needs. The top soil and vegetation is removed from the borrow pit and stockpiled for subsequent rehabilitation of the extraction area. Side slopes in the excavation area not steeper than one vertical to two horizontal for safety reasons.

Old road surfaces, fences, and buildings may need to be removed before construction can begin. Trees in the road construction area may be marked for retention. These protected trees should not have the topsoil within the area of the tree's drip line removed and the area should be kept clear of construction material and equipment. Compensation or replacement may be required if a protected tree is damaged. Much of the vegetation may be mulched and put aside for use during reinstatement. The topsoil is usually stripped and stockpiled nearby for rehabilitation of newly constructed embankments along the road. Stumps and roots are removed and holes filled as required before the earthwork begins. Final rehabilitation after road construction is completed will include seeding, planting, watering and other activities to reinstate the area to be consistent with the untouched surrounding areas.

Processes during earthwork include excavation, removal of material to spoil, filling, compacting, construction and trimming. If rock or other unsuitable material is discovered it is removed, moisture content is managed and replaced with standard fill compacted to 90% relative compaction. Generally blasting of rock is discouraged in the road bed. When a depression must be filled to come up to the road grade the native bed is compacted after the topsoil has been removed. The fill is made by the "compacted layer method" where a layer of fill is spread then compacted to specifications, the process is repeated until the desired grade is reached.

General fill material should be free of organics, meet minimum California bearing ratio (CBR) results and have a low plasticity index. Select fill (sieved) should be composed of gravel, decomposed rock or broken rock below a specified Particle size and be free of large lumps of clay. Sand clay fill may also be used. The road bed must be "proof rolled" after each layer of fill is compacted. If a roller passes over an area without creating visible deformation or spring the section is deemed to comply.

The completed road way is finished by paving or left with a gravel or other natural surface. The type of roadsurface is dependent on economic factors and expected usage. Safety improvements like Traffic signs,Crash barriers, Raised pavement markers, and other forms of Road surface marking are installed.

According to a May 2009 report by the American Association of State Highway and Transportation Officials (AASHTO) and TRIP—a national transportation research organization—driving on rough roads costs the average American motorist approximately $400 a year in extra vehicle operating costs. Drivers living in urban areas with populations more than 250,000 are paying upwards of $750 more annually because of accelerated vehicle deterioration, increased maintenance, additional fuel consumption, and tire wear caused by poor road conditions.

Construction Costs

According to www.nysthruway.gov, some typical costs to construct roads in several USA states include: CONSTRUCTION COST Expressway Section Per-Mile Cost Connecticut Turnpike $3,449,000 New Jersey Turnpike $2,200,000 Pennsylvania Turnpike (Delaware Extension) $1,970,000 Northern Indiana Toll Road $1,790,000 Garden State Parkway $1,720,000 Massachusetts Turnpike $1,600,000 Thruway, New York to Pennsylvania Line $1,547,000 Ohio Turnpike $1,352,000 Pennsylvania Turnpike (early construction) $736,000.

Duplication

When a single carriageway road is converted into dual carriageway by building a second separate carriageway alongside the first, it is usually referred to as duplication or twinning. The original carriageway is changed from two-way to become one-way, while the new carriageway is one-way in the opposite direction. In the same way as converting railway lines from single track to double track, the new carriageway is not always constructed directly alongside the existing carriageway.

Maintenance

Like all structures, roads deteriorate over time. Deterioration is primarily due to accumulated damage from vehicles, however environmental effects such as frost heaves, thermal cracking and oxidation often contribute. According to a series of experiments carried out in the late 1950s, called the AASHO Road Test, it was empirically determined that the effective damage done to the road is roughly proportional to the 4th power of axle weight. A typical tractor-trailer weighing 80,000 pounds (36.287 t) with 8,000 pounds (3.6287 t) on the steer axle and 36,000 pounds (16.329 t) on both of the tandem axle groups is expected to do 7,800 times more damage than a passenger vehicle with 2,000 pounds (0.907 t) on each axle. Potholes on roads are caused by rain damage and vehicle braking or related construction works.

Pavements are designed for an expected service life or design life. In some UK countries the standard design life is 40 years for new bitumen and concrete pavement. Maintenance is considered in the whole life cost of the road with service at 10, 20 and 30 year milestones. Roads can be and are designed for a variety of lives (8-, 15-, 30-, and 60-year designs). When pavement lasts longer then its intended life, it may have been overbuilt, and the original costs may have been too high. When a pavement fails before its intended design life, the owner may have excessive repair and rehabilitation costs. Many concrete pavements built since the 1950s have significantly outlived their intended design lives. Some roads like Chicago, Illinois's "Wacker Drive", a major two-level viaduct in downtown area are being rebuilt with a designed service life of 100 years.

Virtually all roads require some form of maintenance before they come to the end of their service life. Pro-active agencies continually monitor road conditions and apply preventive maintenance treatments as needed to prolong the lifespan of their roads. Technically advanced agencies monitor the road network surface condition with sophisticated equipment such as laser/inertial Profilometers. These measurements include road curvature, cross slope, unevenness, roughness, rutting and texture (roads). This data is fed into a pavement management system, which recommends the best maintenance or construction treatment to correct the damage that has occurred.

Maintenance treatments for asphalt concrete generally include crack sealing, surface rejuvenating, fog sealing, micro-milling and surface treatments. Thin surfacing preserves, protects and improves the functional condition of the road while reducing the need for routing maintenance, leading to extended service life without increasing structural capacity.

Failure to maintain roads properly can create significant costs to society, in a 2009 report released by the American Association of State Highway and Transportation Officials (USA) about 50% of the roads in the USA are in bad condition with urban areas worse. The report estimates that urban drivers pay an average of $746/year on vehicle repairs while the average US motorist pays about $335/year. In contrast, the average motorist pays about $171/year in road maintenance taxes (based on 600 gallons/year and $0.285/gallon tax).

Repair Techniques

There are many repair techniques for roads. Slab Stabilization and Joint Sealing, both Concrete Pavement Restoration (CPR) techniques, are often used in conjunction with other techniques.

Slab Stabilization

Distress and serviceability loss on concrete roads can be caused by loss of support due to voids beneath the concrete pavement slabs. The voids usually occur near cracks or joints due to surface water infiltration. The most common causes of voids are pumping, consolidation, subgrade failure and bridge approach failure. Slab stabilization is a non-destructive method of solving this problem and is usually employed with other Concrete Pavement Restoration (CPR) methods including patching and diamond grinding. The technique restores support to concrete slabs by filing small voids that develop underneath the concrete slab at joints, cracks or the pavement edge. The process consists of pumping a cementations grout or polyurethane mixture through holes drilled through the slab. The grout can fill small voids beneath the slab and/or sub-base. The grout also displaces free water and helps keep water from saturating and weakening support under the joints and slab edge after stabilization is complete. The three steps for this method after finding the voids are locating and drilling holes, grout injection and post-testing the stabilized slabs.

Slab stabilization does not correct depressions, increase the design structural capacity, stop erosion or eliminate faulting. It does, however, restore the slab support, therefore, decreasing deflections under the load. Stabilization should only be performed at joints and cracks where loss of support exists. Visual inspection is the simplest manner to find voids. Signs that repair is needed are transverse joint faulting, corner breaks and shoulder drop off and lines at or near joints and cracks. Deflection testing is another common procedure utilized to locate voids. It is recommended to do this testing at night as during cooler temperatures, joints open, aggregate interlock diminishes and load deflections are at their highest.

Another testing method is ground penetrating radar. It pulses electromagnetic wave technology into the pavement and then ceases the transmission during which the transmitter-receiver detects signals that are deflected from the pavement. Yet another method is the epoxy/core test, which confirms void presence by visual and mechanical methods. It consists of drilling a 25 to 50 millimeter hole through the pavement and into the sub-base with a dry-bit roto-hammer. Next, a two-part epoxy is poured into the hole that is dyed for visual clarity. Once the epoxy is hardened, the technicians drill through the hole. If a void is present, the epoxy will stick to the core and provide physical evidence.

Common stabilization materials are pozzolan-cement grout and polyurethane. The requirements for slab stabilization are strength and the ability to flow into or expand to fill small voids. Colloidal mixing equipment is necessary to use the pozzolan-cement grouts. The contractor should place the grout using a positive-displacement injection pump or a non-pulsing progressive cavity pump. A drill is also necessary but it must produce a clean hole with no surface spalling or breakouts. The injection devices must include a grout packer that is capable of sealing a hole. The injection device must also have a return hose or a fast-control reverse switch in case workers detect slab movement on the uplift gauge. The uplift beam helps to monitor the slab deflection and has to have sensitive dial gauges.

Joint Sealing

Also called joint and crack repair, this method’s purpose is to minimize infiltration of surface water and incompressible material into the joint system. Joint sealants are also used to reduce dowel bar corrosion in Concrete Pavement Restoration (CPR) techniques. Successful resealing consists of old sealant removal, shaping and cleaning the reservoir, installing the backer rod and installing the sealant. Sawing, manual removal, plowing and cutting are methods used to remove the old sealant. Saws are used to shape the reservoir. When cleaning the reservoir, no dust, dirt or traces of old sealant should remain. Thus, it is recommended to water wash, sand-blast and then air blow to remove any sand, dirt or dust. The backer rod installation requires a double-wheeled, steel roller to insert the rod to the desired depth. After inserting the backer rod, the sealant is placed into the joint. There are various materials to choose for this method including hot pour bituminous liquid, silicone and preformed compression seals.

Terminology

The A22(T) near Summer Hill,East Sussex, England, United Kingdom

Road in Kaluga Oblast, Russia

 Alignment (road) - Cross slope/Banking/Superelevation, horizontal and vertical curvature of a road.

 All-weather road - Unpaved road that is constructed of a material that does not create mud during rainfall.

 Adverse camber - the situation where the road slopes towards the outside of a bend, increasing the chance of vehicles travelling at speed toppling or skidding. Usually only a found as a temporary situation during road maintenance.

 Belisha Beacon - an orange globe, lit at night, used to highlight a pedestrian crossing.

 Bollard - Rigid posts that can be arranged in a line to close a road or path to vehicles above a certain width

 Byway - Highway over which the public have a right to travel for vehicular and other kinds of traffic, but which is used mainly as footpaths and bridleways

 Bypass Road that avoids or "bypasses" a built-up area, town, or village

 Bottleneck - Section of a road with a carrying capacity substantially below that of other sections of the same road

 Botts' dots - Non reflective raised pavement marker used on roads

 Cat's eye - reflective raised pavement marker used on roads

 Camber - the curvature of the road surface that encourages surface water to flow freely from the carriageway, or on bends angling of the surface to lean traffic 'into the bend' reducing the chance of a skid.

 Chicane - Sequence of tight serpentine curves (usually an S-shape curve or a bus stop) in a roadway

 Chipseal - Road surface composed of a thin layer of crushed stone 'chips' and asphalt emulsion. It seals the surface and protects it from weather, but provides no structural strength. It is cheaper than asphalt concrete or a concrete, in the U.S. it is usually only used on low volume rural roads

 Corniche - Road on the side of a cliff or mountain, with the ground rising on one side and falling away on the other

 Curb - Edge where a raised pavement/sidewalk/footpath, road median, or road shoulder meets an unraised street or other roadway.

 Curb extension - (or also kerb extension, bulb-out, nib, elephant ear, curb bulge and blister) Traffic calming measure, intended to slow the speed of traffic and increase driver awareness, particularly in built-up and residential neighborhoods.

 Fork - (literally "fork in the road") Type of intersection where a road splits

 Guard rail - Prevents vehicles from veering off the road into oncoming traffic, crashing against solid objects or falling from a road

 Green lane - (UK) Unsurfaced road, may be so infrequently used that vegetation colonises freely, hence 'green'. Many green lanes are ancient routes that have existed for millennia, similar to a Byway

 Gutter - UK a drainage channel between the main carriageway and the edge of the road.

 Interstate Highway System - United States System of Interstate and Defense Highways

 traffic island - UK a small raised area used to help define the traffic flow, and which may also act as a refuge for pedestrians crossing the carriageway or a location for signs, barriers or lights. A synonym for roundabout in some parts of the UK.

 Loose chippings - the hazard of stone chippings which have come loose.

 Median - On divided roads, including expressways, motorways, or autobahns, the central reservation (British English), median (North American English), median strip (North American English and Australian English), neutral ground [Louisiana English] or central nature strip (Australian English) is the area which separates opposing lanes of traffic

 Mountain pass - Lower point that allows easier access through a range of mountains

 Milestone - One of a series of numbered markers placed along a road at regular intervals, showing the distance to destinations.

 National Highway - Road built and maintained by a national authority.

 Pavement - The road regarded as a geoconstruction. In the UK the term is road surface and the pavement is a pedestrian walkway alongside the road.

 Pedestrian crossing - Designated point on a road at which some means are employed to assist pedestrians wishing to cross safely

 Pelican crossing - (officially Pelicon crossing) UK a PEdestrian LIght CONtrolled crossing.

 Private highway - Highway owned and operated for profit by private industry

 Private road - Road owned and maintained by a private individual, organization, or company rather than by a government

 Public space - Place where anyone has a right to come without being excluded because of economic or social conditions

 Pullout (layby, pull-off) - A paved area beside a main road where cars can stop temporarily to let another car pass.

 Ranch road - U.S. road which serves to connect rural and agricultural areas to market towns

 Road number - Often assigned to a stretch of public roadway. The number chosen is often dependent on the type of road, with numbers differentiating between interstates, motorways, arterial thoroughfares, and so forth

 Road-traffic safety - Process to reduce the harm (deaths, injuries, and property damage) resulting from crashes of road vehicles traveling on public roads

 Roadworks - Part or all of the road has to be occupied for work or maintenance relating to the road

 Roughness - Deviations from a true planar pavement surface, which affects vehicle suspension deflection, dynamic loading, ride quality, surface drainage and winter operations. Roughness have wavelengths ranging from 500 mm up to some 40 m. The upper limit may be as high as 350 m when considering motion sickness aspects; motion sickness is generated by motion with down to 0.1 Hz frequency; in an ambulance car driving 35 m/s (126 km/h), waves with up to 350 m will excite motion sickness.

 Roundabout UK a road junction where typically three or more roads are joined by a circular section of road. Traffic 'on the roundabout' has priority over traffic on approach roads, unless indicated otherwise. In countrys where traffic drives on the left the roundabout is travelled in a clockwise direction. Also known as an roundabout in parts of the UK.

 Shoulder - A clear, level area beside the driving lane(s). It helps support the roadway, helps drain the pavement, provides room for bicyclists and, in areas without sidewalks, pedestrians, allows disabled to get out of the road; a hard shoulder is paved, a soft shoulder is unpaved.

 State highway - Road numbered by the state, falling below numbered national highways (like U.S. Routes) in the hierarchy or a road maintained by the state, including nationally-numbered highways

 Texture (roads) - Deviations from a true planar pavement surface, which affects the interaction between road and tire. Microtexture have wavelengths below 0.5 mm, Macrotexture below 50 mm and Megatexture below 500 mm.

 Traffic calming - Set of strategies used by urban planners and traffic engineers which aim to slow down or reduce traffic, thereby improving safety for pedestrians and bicyclists as well as improving the environment for residents

 Traffic light - also known as a traffic signal, stop light, stop-and-go lights, robot or semaphore, is a signaling device positioned at a road intersection, pedestrian crossing, or other location in order to assign right of way to different approaches to an intersection

 Zebra Crossing - UK a pedestrian crossing marked by black and white stripes on the carriageway.

flexible pavement design

2010-01-20T20:59:00.000-08:00

Roman roads II

2010-01-19T22:33:00.001-08:00

Roman Roads

The Romans, for military, commercial and political reasons, became adept at constructing roads, which they called 'viae' (plural of singular via). It means "to go" with the sense of transporting in a vehicle. Viae were always intended primarily as carriage roads, the means of carrying material from one location to another.

The Roman roads were essential for the growth of their empire, by enabling them to move armies speedily and by sustaining land transport for Roman mercantilism. A proverb says that "all roads lead to Rome". Roman roads were designed that way to hinder provinces organising resistance against the Empire. At its peak, the Roman road system spanned 53,000 miles and contained about 372 links.

These long highways were very important in maintaining both the stability and expansion of the empire. The legions made good time on them, and some are still used millennia later. In late Antiquity, the same roads, by offering avenues of invasion to the barbarians, contributed to Roman military reverses.

The Roman Road System

Types of Roads

Roman roads vary from simple corduroy roads to paved roads using deep roadbeds of tamped rubble as an underlying layer to ensure that they kept dry, as the water would flow out from between the stones and fragments of rubble, instead of becoming mud in clay soils.

Prepared viae began in history as the streets of Rome. The laws of the Twelve Tables, dated to approximately 450 BC, specify that a road shall be 8 feet wide where straight and 16 where curved. The tables command Romans to build roads and give wayfarers the right to pass over private land where the road is in disrepair. Building roads that would not need frequent repair therefore became an ideological objective.

Roman law defined the right to use a road as a servitus, or claim. The jus eundi ("right of going") established a claim to use an iter, or footpath, across private land; the ius agendi ("right of driving"), an actus, or carriage track. A via combined both types of servitutes, provided it was of the proper width, which was determined by an arbiter. The default width was the latitudo legitima of 8 feet. In these rather dry laws we can see the prevalence of the public domain over the private, which characterized the republic.

With the conquest of Italy prepared viae were extended from Rome and its vicinity to outlying municipalities, sometimes overlying earlier roads.

Building viae was a military responsibility and thus came under the jurisdiction of a consul. The process had a military name, viam munire, as though the via were a fortification. Municipalities, however, were responsible for their own roads, which the Romans called viae vicinales.A via connected two cities. Some links in the network were as long as 55 miles. The builders always aimed at a regulation width, but actual widths have been measured at between 3' 9" and 24'.

The builders aimed at directional straightness. Many long sections are ruler-straight, but it should not be thought that all of them were. The Roman emphasis on constructing straight roads often resulted in steep grades relatively impractical for most economic traffic: over the years the Romans themselves realized it and built longer, but more manageable, alternatives to existing roads.

Viae were generally centrally placed in the countryside. Features off the via were connected to the via by viae rusticae, or secondary roads. Either main or secondary roads might be paved, or they might be left unpaved, with a gravel surface, as they were in North Africa. These prepared but unpaved roads were viae glareae or sternendae ("to be strewn"). Beyond the secondary roads were the viae terrenae, "dirt roads".

A road map of the empire reveals that it was laced fairly completely with a network of prepared viae. Beyond the borders are no roads; however, one might presume that footpaths and dirt roads allowed some transport.

Traveling a Road

Before 250 BC, the via Appia, and after 124 BC, most viae, were divided into numbered miles by milestones. The words we translate as mile are milia passuum, "one thousand of paces", which amounted to about 1620 yards, 1480 meters.

A milestone, or miliarium, was a circular column on a solid rectangular base, set two feet into the ground, standing several feet high, 20" in diameter, weighing about 2 tons.

At the base was inscribed the number of the mile relative to the road it was on. In a panel at eye-height was the distance to the forum at Rome and various other information about the officials who made or repaired the road and when.

These miliaria are valuable historical documents now. Their inscriptions are collected in the Corpus Inscriptionum Latinarum.

The Romans had a preference for standardization whenever they could, and so Augustus, after becoming permanent commissioner of roads in 20 BC, set up the miliarium aurum (golden milestone) near the temple of Saturn. All roads were considered to begin from this gilded bronze monument. On it were listed all the major cities in the empire and distances to them. Constantine called it the umbilicus Romae (navel of Rome).

Milestones permitted distances and locations to be known and recorded exactly. It wasn't long before historians began to refer to the milestone at which an event occurred.

Way Stations

A legion on the march didn't need a way station, as it brought its own baggage train (impedimenta) and constructed its own camp (castra) every evening at the side of the road. Other officials or people on official business, however, had no legion at their service, and so the government maintained way stations, or mansiones ("staying places"), for their use. Passports were required for identification.

Carts could travel about 8 miles per day, pedestrians a little more, and so each mansio was about 15 to 18 miles from the next one. There the official traveller found a complete villa dedicated to his refreshment. Oftentimes a permanent military camp or a town grew up around the mansio.

Non-official travellers needed refreshment too, and at the same locations along the road. A private system of cauponae were placed near the mansiones. They performed the same functions but were somewhat disreputable, as they were frequented by thieves and prostitutes.

Graffiti decorate the walls of the few whose ruins have been found.

Genteel travelers needed something better than cauponae. In the early days of the viae, when little unofficial existed, houses placed near the road were required by law to offer hospitality on demand.

Frequented houses no doubt became the first tabernae, which were hostels, rather than the "taverns" we know today.

As Rome grew, so did its tabernae, becoming more luxurious and acquiring good or bad reputations as the case may be. One of the best hotels was the Tabernae Caediciae at Sinuessa on the Via Appia. It had a large storage room containing barrels of wine, cheese and ham.

Many cities of today grew up around a taberna complex, such as Rheinzabern in the Rhineland, and Saverne in Alsace.

A third system of way stations serviced vehicles and animals: the mutationes ("changing stations"). They were located every 12-18 miles. In these complexes, the driver could purchase the services of wheelrights, cartwrights, and equarii medici, or veterinarians.

Using these stations in chariot relays, the emperor Tiberius hastened 500 miles in 24 hours to join his brother, Drusus Germanicus, who was dying of gangrene as a result of a fall from a horse.

Vehicles

Roman law and tradition forbade the use of vehicles in urban areas, except in certain cases. Married women and government officials on business could ride. The Lex Iulia Municipalis restricted commercial carts to night-time access to the city within the walls and within a mile outside the walls. Outside the cities, Romans were avid riders and rode on or drove quite a number of vehicle types, some of which are mentioned here.

For purposes of description, Roman vehicles can be divided into the car, the coach and the cart. Cars were used to transport one or two individuals, coaches were used to transport parties, and carts to transport cargo.

Of the cars, the most popular was the currus ("car"), a standard chariot form descending to the Romans from a greater antiquity. The top was open, the front closed. One survives in the Vatican. It carried a driver and a passenger. A currus of two horses was a biga; of three horses, a triga; and of four horses a quadriga. The tires were of iron. When not in use, its wheels were removed for easier storage.

A more luxurious version, the carpentum, transported women and officials. It had an arched overhead covering of cloth and was drawn by mules. A lighter version, the cisium, equivalent to our gig, was open above and in front and had a seat.

Drawn by one or two mules or horses, it was used for cab work, the cab drivers being called cisiani. The builder was a cisarius.Of the coaches, the main stay was the raeda or reda, which had 4 wheels. The high sides formed a sort of box in which seats were placed, with a notch on each side for entry. It carried several people with baggage up to the legal limit of 1000 pounds. It was drawn by teams of oxen, horses or mules. A cloth top could be put on for weather, in which case it resembled a covered wagon.

The reda was probably the main vehicle for travel on the viae. Redae meritoriae were hired coaches. The fiscalis reda was a government coach. The driver and the builder were both named a raedarius.Of the carts, the main one was the plaustrum or plostrum. This was simply a platform of boards attached to wheels and a cross-tree. The wheels, or tympana, were solid and were several inches thick. The sides could be built up with boards or rails. A large wicker basket was sometimes placed on it. A two-wheel version existed. The 4-wheel type was the plaustrum maius.

The military used a standard wagon. Their transportation service was the cursus clabularis, after the standard wagon, called a carrus clabularius, clabularis, or clavularis, or clabulare. It transported the impedimenta, or baggage of a column.

Post Offices

Two postal services were available under the empire, a public and a private.

The Cursus publicus, founded by Augustus, carried the mail of officials by relay throughout the Roman road system. The vehicle for carrying mail was a cisium with a box, but for special delivery, a horse and rider was faster. A relay of horses could carry a letter 500 miles in 24 hours. The postman wore a characteristic leather hat, the petanus. The postal service was a somewhat dangerous occupation, as postmen were a target for bandits and enemies of Rome.

Private mail of the well-to-do was carried by tabellarii, an organization of slaves available for a price.

The Itinerary

The Romans and ancient travelers in general did not use maps. They may have existed as specialty items in some of the libraries, but they were hard to copy and were not in general use. On the Roman road system, however, the traveller needed some idea of where he was going, how to get there, and how long it would take.

The itinerarium filled this need. In origin it was simply a list of cities along a road. It was only a short step from lists to a master list. To sort out the lists, the Romans drew diagrams of parallel lines showing the branches of the roads. Parts of these were copied and sold on the streets.

The very best featured symbols for cities, way stations, water courses, and so on. They cannot be considered maps, as they did not represent landforms.

The Roman government from time to time undertook to produce a master itinerary of all Roman roads. Julius Caesar and Mark Antony commissioned the first known such effort in 44 BC. Zenodoxus, Theodotus and Polyclitus, three Greek geographers, were hired to survey the system and compile a master itinerary. This task required over 25 years.

The result was a stone engraved master itinerarium set up near the Pantheon, from which travelers and itinerary sellers could make copies.

Another master itinerary, the Itinerarium Provinciarum Antonini Augusti (the Antonine Itinerary) is known to have been undertaken in 217 AD. It was first printed in 1521 and after many reprintings survives today. Another major surviving itinerary is the Tabula Peutingeriana. The Ravenna Cosmography dates from the 7th century, but repeats earlier material.

Archaeology has turned up some itinerary material in unexpected places. The Cups of Cadiz, four silver cups found by workmen excavating a foundation at Bracciano in 1852, are engraved with the names and distances of stations between Cadiz and Rome.

The term itinerary changed meaning over the centuries. In the Itinerarium Burdigalense (Bordeaux Pilgrim, 333 AD), the itinerary is a description of what route to take to the Holy Land. The Itinerarium Alexandri is a list of the conquests of Alexander the Great. Today it means either a travel journal or a list of recommended stops.

Construction of a Road

The Team

The distinction between staff and line officers applied to the Roman army as well. Among the staff officers were a unit called the architecti, "chief builders", responsible for all military construction, which road-building was. These were required to be educated men. Geometry, of course, was a central requirement of their education.

The architecti had a full-time staff of agrimensores ("land surveyors") and libratores ("levellers"). The teams of construction workers were taken ad hoc from the ranks of the legionaries. In addition to his arms, his rations and his utensils, every soldier carried a saw, hatchet, sickle, pick and spade. Augustus decided as a matter of policy to keep the soldiers busy (and therefore out of trouble) by turning them to construction.

This labor improved their strength and stamina, rendering them almost unbeatable, but elicited constant complaint about the back-breaking work, which sometimes turned to mutiny.

As might have been expected, the legions sought involuntary assistance for their hard labor. Slaves, prisoners of war and convicted criminals often performed the most difficult tasks of quarrying and transporting stone. They were also used for road repair. Whether they performed these tasks in chains is not known. Whipping, however, was common, for which the verb was verberare. Beatings were by no means confined to slaves. Indeed, one of the symbols of Roman authority was the fasces, a bundle of whips.

The Method

The Romans are believed to have inherited the art of road construction from the Etruscans. No doubt the art grew as it went along and also incorporated good ideas from other cultures.

After the architecti looked over the site of the proposed road and determined roughly where it should go, the agrimensores went to work surveying the road bed. They used two main devices, the rod and one called the groma, which helped them obtain right angles.

The gromatici, the Roman equivalent of rod men, placed rods and put down a line called the rigor. As they did not possess anything like a transit, an architect tried to achieve straightness by looking along the rods and commanding the gromatici to move them as required.

Using the gromae they then laid out a grid on the plan of the road.

The libratores began their work. Using ploughs and legionaries with spades, they excavated the road bed down to bed rock or at least to the firmest ground they could find.

The excavation was called the fossa, "ditch." It was typically 15' below the surface, but the depth varied according to terrain.

The road was constructed by filling the ditch. The method varied according to geographic locality, materials available and terrain, but the plan, or ideal at which the architect aimed was always the same. The roadbed was layered.

Into the fossa was dumped large amounts of rubble, gravel and stone, whatever fill was available. Sometimes a layer of sand was put down, if it could be found. When it came to within a few feet of the surface it was covered with gravel and tamped down, a process called pavire, or pavimentare. The flat surface was then the pavimentum. It could be used as the road, or additional layers could be constructed. A statumen or "foundation" of flat stones set in cement might support the additional layers.

The final steps utilized concrete, which the Romans had exclusively rediscovered. They seem to have mixed the mortar and the stones in the fossa. First a several-inch layer of course concrete, the rudus, then a several-inch layer of fine concrete, the nucleus, went onto the pavement or statumen. Into or onto the nucleus went a course of polygonal or square paving stones, such as you see in the picture, called the summa crusta. The crusta was crowned for drainage.It is unclear that any standard terminology was used; the words for the different elements perhaps varied from region to region.

Today the concrete has worn from the spaces around the stones, giving the impression of a very bumpy road, but the original surface was no doubt much closer to being flat. These remarkable roads are resistant to rain, freezing and flooding. They needed little repair.

Surpassing Obstacles

Roman architecti preferred to engineer solutions to obstacles rather than circumvent them.

River crossings were achieved by bridges, or pontes. Single slabs went over rills. A bridge could be of wood, stone, or both. Wooden bridges were constructed on pilings sunk into the river, or on stone piers. Larger or more permanent bridges required arches. Roman bridges were so well constructed that many are in use today.

Causeways were built over marshy ground. The road was first marked out with pilings. Between them were sunk large quantities of stone so as to raise the causeway 6 feet above the marsh. In the provinces, the Romans often did not bother with a stone causeway, but used log roads (pontes longi).

Outcroppings of stone, ravines, or hilly or mountainous terrain called for cuttings and tunnels. Roman roads generally went straight up and down hills, rather than in a serpentine pattern. Grades of 10%-12% are known in ordinary terrain, 15%-20% in mountainous country.

Financing road building and repair was a government responsibility. The officials tasked with fund raising were the curatores viarum, in which you can see the English word, curator. They had a number of methods available to them. Private citizens with an interest in the road could contribute to its repair. High officials might distribute largesse to be used for roads. Censors, who were in charge of public morals and public works, were expected to fund repairs sua pecunia. Beyond those means, taxes were required.

The beauty and grandeur of the roads might tempt us to believe that any Roman citizen could use them for free, but this was not the case. Tolls abounded, especially at bridges. Often they were collected at the city gate. Freight was made heavier still by import and export taxes. These were only the charges for using the roads. Costs of services on the journey went up from there.

References - Wikipedia

And Thanks to http://www.crystalinks.com/romeroads.html

Indian roads- present status

2010-01-19T21:38:00.000-08:00

indian Roads-1

From a rail dominant economy in the 1950s, India has become a decidedly road dominant economy in the 1990s. The roadways have grown rapidly in independent India. Ranging from the cross-country link of the national highways to the roads in the deepest interiors, the country has a road network of 3.3 million km, making it the second largest road network in the world! The source for this information - The World Book Encyclopedia. US leads the world with 6.43 m km of roadways. China has 1.87 m km's and Brazil has 1.75 m km's and Japan at 1.18 m km's.

Estimates indicate that the country could make economic savings to the tune of Rs 200-300 billion (US$ 5.7-8.6 billion) per annum through improved road infrastructure.

The annual average rate of traffic growth has been 8 to 10 percent. It is estimated that of the total requirement of Rs 300 billion (US$ 8.57 billion) for development of State Highways, the private sector would be required to invest nearly 20 percent.

For effective management and administration, Indian roads are divided into National Highways, State highways, district roads and village roads. Presently, the functions relating to externally-aided projects, implementation of policy on private sector participation and development of wayside amenities along the National Highways, have been assigned to National Highway Authority of India ("NHAI"). State highways, district roads and village roads are the responsibility of the State governments.

An Implementing Agency ('IA') carries out the policy implementation and regulatory functions. The IA ensures that the highway facility is available to all users on equal terms and no user is charged more than the notified fee, or harassed in any manner or subject to any unfair or restrictive practices.

Thanks to http://www.diehardindian.com/

roman roads

2010-01-19T21:32:00.000-08:00

Roman Roads

It is often said that "all roads lead to Rome," and in fact, they once did. The road system of the Ancient Romans was one of the greatest engineering accomplishments of its time, with over 50,000 miles of paved road radiating from their center at the militaries aurum in the Forum in the city of Rome. Although the Roman road system was originally built to facilitate the movement of troops throughout the empire, it was inevitably used for other purposes by civilians then and now.

ROMAN ENGINEERING

Of course, the roads were used for trade, as were the waterways surrounding and connecting parts of the Roman Empire to itself and the rest of the known world. The Romans had exceptional nautical technology for their time; however their network of roads, even with the perils of land travel, was unparalleled in convenience and was often the only choice for travel or shipping goods. The Romans were the first ancient civilization to build paved roads, which did not prevent travel during or after inclement weather. Indeed, mud or gravel would hinder, if not completely halt many vehicles pulled by animals or other people, not to mention discourage travelers on foot. Roman engineers, however, did not stop with just paving Roman roads. Roads were crowned—that is, they were higher in the middle than on the sides to allow water to run off—and they often had gutters for drainage along the shoulders. Probably the most incredible engineering feat concerning the Roman road system, though, is how well the roads were built. Many are still major thoroughfares for cars today. Indeed, their road-building methods were unsurpassed until the invention of the macadam in the 19th century. These technological advantages made travel and the shipment of goods across land much easier. Romans shipped lots of goods within the vast expanses of their empire as well as to the rest of the world. Goods were constantly being shipped throughout the empire, depending on the location within the Empire, as well as supply and demand. Present-day Great Britain, for example, was a valuable possession to the Romans because of its silver deposits, which were used for jewelry and money. Great Britain also supplied a lot of wool to the rest of the empire. From the southeastern corner of the empire, the Romans imported many dyes for clothing and make-up from the Near East. Over-water transportation usually played a role in imports from the Near East or Africa, from whence they imported Egyptian cotton or exotic animals for the gladiators to fight. Of course, Rome was connected to the Far East via the Silk Road, the source of silk and other goods imported from Asia. No matter what or from where, if the Romans wanted something exotic, it was probably shipped into Rome.

ROMAN TRADE

As well as they designed their road network, travel on land was often difficult and dangerous for the Romans. Progress was slow compared to today’s standards and a person traveling on foot would be lucky to travel 35 miles a day. The more affluent Romans had more choices as to how they could travel. People who could afford to traveled in litters carried by six to eight men or several mules. Small groups of travelers, such as families, rode in raedae (carriages). People in a hurry, such as messengers from the emperor, rode in cisii, a light carriage like a chariot. However, travel for anybody by any mode of transportation was not safe, particularly at night. Roadside inns were strategically located in the countryside at about a days’ journey apart. The inns themselves were not safe. Fights broke out. Murders occurred. Whenever possible, a traveler stayed with a friend of the family or even a friend of a friends’ family.

CONCLUSION

The ancient Romans accomplished many feats. They had incredible technological advantages and made advancements that dwarfed those of other civilizations of their time or hundreds of years beyond. It is their advancements we often take for granted that make them one of the most prevalent and influential peoples on our society today—2000 years after their fall—in more ways than just language.

Thanks to : http://library.thinkquest.org/13406/rr/

Education System in INDIA.........

2009-01-01T03:34:00.000-08:00

People are discusing about the basic needs like food,water and electricity to reach every corner of india.At the same time they are forgetting the most important need i.e EDUCATION ......this is the situation in india that people starving for good and value added (lecturers,teachers,institutions)education system........the standards are deteriorating rapidly .If we allow this to continue one day we will see the system collapse.
Its time to encourage proffessionals in teaching to make the situation better and to improve the standards......iam not a victim but i suffered with this system.......so i dont like to let my people suffer........
I am welcoming your remarks.........

ALL ROADS LEADS TO ROME

My visit to Mahabalipuram(mamallapuram)

Mahabalipuram

Mahabalipuram (Source: Archeological Survey of India, Wikipedia)

Group of Monuments at Mahabalipuram

Hampi - My favorite Tourist Spot

Geography

Important sites at and near Hampi

Temples

Hampi - the story that unrevealed

Hampi - the story that unrevealed

Pavemnt analysis and design III

Bituminous recycling

Design Principle Based

Figure 13 Rich bottom pavement

Inverted pavements

Bituminous pavement with cemented base

Mix design considerations

Non-standard gradation

Stone matrix asphalt

Porous pavement

CLOSING REMARKS

Pavemnt analysis and design II

Cement Concrete as a pavement materialIntroduction

Aggregates

Mix design

Curing of concrete

Aggregate modification

Pavement deisgn and analysis

India's first 84-m high Roller Compacted Concrete dam

Roller-compacted concrete

From Wikipedia, the free encyclopedia

All about Road

flexible pavement design

Roman roads II

Roman Roads

Indian roads- present status

roman roads

Roman Roads

ROMAN ENGINEERING

ROMAN TRADE

CONCLUSION

Education System in INDIA.........

Cement Concrete as a pavement material
Introduction