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

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

Roman roads II

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

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

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.........

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.........