Road

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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 of Elea. It is paved with limestone blocks, with a gutter for the drainage of rain water.

Main article: History of road transport safety reflectors

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. oil absorbents

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

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

The timber trackway; Sweet Track causeway in England, is one of the oldest engineered roads discovered and the oldest timber trackway 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. 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, 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 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. 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 in Carmarthenshire 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

The Transfgran in Romania, first built as a military road.

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 dust 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. 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 generate 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.[citation needed]

Driving on the right or the left

A sign on Australia's Great Ocean Road reminding foreign motorists to keep left.

Main article: Driving on the left or right

Traffic flows on the right or on the left side of the road depending on the country. In countries where traffic flows on the right, traffic signs are mostly on the right side of the road, roundabouts and traffic circles go counter-clockwise/anti-clockwise, and pedestrians crossing a two-way road should watch out for traffic from the left first. In countries where traffic flows on the left, the reverse is true.

About 34% of the world by population drive on the left, and 66% keep right. By roadway distances, about 28% drive on the left, and 72% on the right, even though originally most traffic drove on the left worldwide.

Construction

A road being torn up.

Surveyor at work with a leveling instrument.

Asphalt layer and roller

Sub-base layer composed of cement-based material being applied during construction of the M8 motorway in Ireland.

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. (pg15) and may be required to meet standards set by law 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 building equipment 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 Radii and gradient are designed and staked out to best suit the natural ground levels and minimize the amount of cut and fill. (page34) Great care is taken to preserve reference Benchmarks (page59)

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 catchment with approval for the outfall from the appropriate authority to a watercourse, creek, river or the sea for drainage discharge. (page38 to 40)

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. (page 53 to 56 )

Road construction on Marquette Avenue in Minneapolis, Minnesota, United States

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. (page 66 to 67 )

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. (page 68 to 69 ).

Typical pavement strata for a heavily traveled road

General fill material should be free of organics, meet minimum California bearing ratio (CBR) results and have a low plasticity index. The lower fill generally comprises sand or a sand-rich mixture with fine gravel, which acts as an inhibitor to the growth of plants or other vegetable matter. The compacted fill also serves as lower-stratum drainage. Select second 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. (page 70 to 72 )

The completed road way is finished by paving or left with a gravel or other natural surface. The type of road surface 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 national transportation research organizationriving 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, twinning or doubling. 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 monitior 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 cementitous 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 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

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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

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

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

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 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.

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.

See also

Roads portal

AASHO Road Test

Banked turn

Corpse roads

Cross slope

Design Manual for Roads and Bridges

Drainage gradient

Equestrian use of roadways

Friction

Habitat fragmentation

International_Grooving_&_Grinding_Association

Inca road system

Line source

List of roads and highways

List of OECD countries by road network size

Infrastructure

Pavement management system

Ride quality

Road movie

Road runner

Road slipperiness

Road test

Roadway air dispersion model

Roadway noise

Street

Strip road

Texture (roads)

Towing

Trade route

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^ "Road Dust - Something To Sneeze About." Science Daily, 1999-11-30.

^ United States. National Research Council. Washington, DC. "Urban Stormwater Management in the United States." October 15, 2008. pp. 5, 110.

^ G. Allen Burton, Jr., Robert Pitt (2001). Stormwater Effects Handbook: A Toolbox for Watershed Managers, Scientists, and Engineers. New York: CRC/Lewis Publishers. ISBN 0-87371-924-7. http://unix.eng.ua.edu/~rpitt/Publications/BooksandReports/Stormwater%20Effects%20Handbook%20by%20%20Burton%20and%20Pitt%20book/MainEDFS_Book.html.  Chapter 2.

^ Charles Seawell and Newland Agbenowosi (1998)."Effects of Road Deicing Salts on Groundwater Systems." Virginia Polytechnic Institute, Department of Civil Engineering.

^ University of Minnesota (2009). "U of M research finds most road salt is making it into the state's lakes and rivers." 2009-02-10.

^ "Why In Britain Do We Drive On The Left?". 2Pass.co.uk. 1996-2007. http://www.2pass.co.uk/goodluck.htm. Retrieved 2007-03-24. 

^ Kincaid, Peter (1986). The Rule of the Road: An International Guide to History and Practice. Greenwood Press. ISBN 0-313-25249-1. http://www.amazon.com/Rule-Road-International-History-Practice/dp/0313252491. 

^ Lucas, Brian (2005). "Which side of the road do they drive on?". http://www.brianlucas.ca/roadside/. Retrieved 2006-08-03. 

^ "Why do some countries drive on the right and others on the left?". http://users.pandora.be/worldstandards/driving%20on%20the%20left.htm. 

^ "Kitsap County Road Standards 2006" (Doc). Kitsap County, Washington. 2006. http://www.google.com/url?sa=t&ct=res&cd=4&url=http%3A%2F%2Fwww.kitsapgov.com%2FPW%2Fpdf%2FRevised%2520Road%2520Standards.doc&ei=CR4oRqeuCIuYgQOonvGyDQ&usg=AFrqEzc34dXvKRHE9kUtBqd8RfqzfNI2rA&sig2=nrd9wbiu_sCE4shhBWX6jw. Retrieved 2007-04-20. 

^ "Washington State County Road Standards". Chapter 35.78 RCW requires cities and counties to adopt uniform definitions and design standards for municipal streets and roads. Municipal Research & Services Center of Washington. 2005. http://www.mrsc.org/subjects/Transpo/stand/CoRdStand.aspx. Retrieved 2007-04-20. 

^ a b c d e f g h Shire of Wyndham East Kimberly (October 2006). "Guidelines for rural road design and construction technical specifications" (PDF). Western Australia (The Last Frontier). http://www.thelastfrontier.com.au/Publications/06K027005-061019-Rural%20Road%20Technical%20Specification%20complete%20(3).pdf. Retrieved 2007-04-24. 

^ "Road Building Equipment". Constructing roads into forestry work areas. Caterpillar. 2007. http://www.cat.com/cda/layout?m=62323&x=7. Retrieved 2007-04-20. 

^ "Volvo Construction Equipment (Europe)". Building the cities, towns, streets, highways and bridges in your neighborhood and in communities around the globe. Volvo. 2007. http://www.volvo.com/constructionequipment/europe/en-gb/work+solutions/government/introduction.htm. Retrieved 2007-04-20. 

^ Glossary: Princes Highway, Traralgon Bypass - Planning Assessment Report at The State of Victoria

^ "ISAP 9th Conference Titles & Abstracts (#09044)". Effects of Frost Heave on the Longitudinal Profile of Asphalt Pavements in Cold Regions. International Society for Asphalt Pavements. August 2002. http://www.asphalt.org/Pubs/9th_conf_abst.html. Retrieved 2007-05-13. 

^ The Motorway Achievement: Frontiers of Knowledge and Practice. Thomas Telford. 2002. pp. 252. ISBN 0727731971. http://books.google.com/books?id=7Yqxyefv-VAC&pg=PA252&ots=Yvl1puH55J&dq=4th+power+of+axle+weight&sig=qNz9nc_S0HgJDblEONAZXcS605g. 

^ O'Flaherty, Coleman A. (2002). Highways: The Location, Design, Construction & Maintenance of Road Pavements. Elsevier. pp. 252. ISBN 0750650907. http://books.google.com/books?id=Ren4sWQ3jKkC&pg=PA252&ots=9b8s3lyHfg&dq=Pavements+are+designed+for+an+expected+service+life&sig=Wl0QDnn4_4vaXb-TQI8TiBarVAw. 

^ "Road Map to the Future". United States Department of Transportation - Federal Highway Administration. July/August 2002. http://www.tfhrc.gov/pubrds/02jul/10.htm. Retrieved 2007-05-13. 

^ ISG Resources, Inc (December 2003). "Fly Ash Concrete Design for Chicago 100-Year Road Structure" (PDF). Case Study. U.S. Environmental Protection Agency. http://www.epa.gov/epaoswer/osw/conserve/c2p2/cases/wacker-dr.pdf. Retrieved 2007-05-13. 

^ "Thin Surfacing - Effective Way of Improving Road Safety within Scarce Road Maintenance Budget" (PDF). Paper for presentation at the 2005 Annual Conference of the Transportation Association of Canada in Calgary, Alberta. Transportation Association of Canada. 2005. http://www.tac-atc.ca/english/pdf/conf2005/s16/uzarowski2.pdf. Retrieved 2007-05-14. 

^ Minnesota DOT

^ Practical guidelines for CPR of Urban Roads: A compelling need for preserving city concrete streets led to the development of a methodology for scoping repairs and the undertaking of a comprehensive concrete pavement repair program in Grand Rapids, Michigan. June 2005. Better Roads.

^ IGGA

^ Minnesota DOT

^ How States Preserve Concrete Pavements: CPR pays off in extra pavement life. Better Roads. August 2005.

^ CPR brings dying pavement back to life: Georgia continues to be the leader in concrete pavement restoration, but as the word spreads other states are beginning to use this system to restore deteriorating pavements. April 1997, Roads & Bridges Magazine

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v  d  e

Roads and junctions

 

Types of road

High-speed

Access via

interchanges

Autobahn   Autocesta  Autopista  Autostrada  Autostrasse  Auto-estrada  Freeway  Motorway  HQDC

Other access

Arterial road  Collector/distributor road  Distributor road  Dual carriageway/divided highway  Express-collector setup  Expressway  Farm-to-market road  Highway  Link road  Parkway  Super two  Two-lane expressway  2+1 road   2+2 road   Bundesstrae

Low-speed

Standard

Boulevard  Business route  Frontage road  Regional road  Road  Single carriageway  Street   Kreisstrae

Low traffic

Alley  Backroad  Cul-de-sac  Driveway  Lane  Primitive road  Range road

Other

Concurrency  Concession road  Private highway  Special route   Toll road

Surfaces

Asphalt concrete  Brick  Chipseal  Cobblestone  Concrete  Corduroy  Dirt  Gravel  Ice  Macadam  Oiled (bitumen)  Plank  Tarmac

List of road types by features

 

Road junctions

Interchanges

(grade-separated)

Cloverleaf  Diamond  Directional T  Diverging diamond  Parclo  Trumpet  SPUI  Stack  Three-level diamond  Raindrop  Roundabout interchange

Intersections

(at-grade)

Box junction  Continuous flow  Hook turn  Jughandle  Michigan left  Quadrant roadway  Roundabout  Superstreet  3-way junction  Traffic circle  Bowtie

v  d  e

Types of road junction

Interchanges

(grade-separated)

Cloverleaf  Diamond  Directional T  Diverging diamond  Dumbbell  Parclo  Raindrop  Roundabout interchange  SPUI  Stack  Three-level diamond  Trumpet

Intersections

(at-grade)

Bowtie  Box junction  Continuous flow  Hook turn  Jughandle  Median u-turn crossover  Quadrant roadway  Superstreet  3-way junction  Roundabout  Traffic circle or Rotary

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