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[Middle English rode, rade, a riding, road, from Old English rād.]
noun
Idioms beginning with road:
road hog
road show
road to hell is paved with good intentions, the
See also
For more information on road, visit Britannica.com.
Except for a brief spurt of road building around 1800, the continental United States was extended from the Atlantic coast to the Pacific without the benefit of good roads. The United States had few roads prior to the twentieth century, and most were of poor quality. In towns, most roads were unpaved until the late nineteenth century, and in rural areas most roads were little more than dirt paths into the twentieth century. Federal programs during the 1910s and again during the 1950s eventually provided the United States with adequate roads for motor vehicles.
Roads in Towns Before 1900
On maps, towns in colonial America and the newly independent nation appeared to have excellent roads. Colonial towns, such as Annapolis, Philadelphia, Savannah, and Williamsburg, were built according to founders' designs. Principal functions of the town, including court, church, market, and school, were placed at key locations, and main streets were laid out to connect the buildings.
Squares and circles were placed at the points where the principal streets intersected. Other colonial towns, such as Boston and New York, had random mazes of streets said to be laid out by wandering cows.
Nineteenth-century cities were typically designed around a grid road pattern. Most dramatically, the Commissioners of Manhattan in 1811 laid out the entire island north of the colonial southern tip in a grid of wide avenues running north-south and narrow streets running east-west. As the city grew rapidly during the nineteenth century, the avenues were extended north and crossed by higher-numbered east-west streets. The rectangular blocks formed by the streets were more easily bought and sold by speculators and developers than the irregularly shaped parcels of most colonial settlements.
The main roads of colonial towns were laid with cobblestones obtained from ship ballast. Gravel and blocks made of wood or granite were also used for some road paving in nineteenth-century towns. Although travel on these uneven surfaces was jolting, stones and blocks were an improvement on the vast majority of roads made of dirt. In 1890 the percentage of unsurfaced roads exceeded 30 percent in Washington, D.C., 40 percent in Pittsburgh, and 80 percent in New Orleans and Kansas City. In smaller towns nearly all streets were dirt or gravel. Even Manhattan had many dirt roads in the late nineteenth century.
As cities grew rapidly during the nineteenth century, the poor condition of the roads became an important sanitary issue, not just an inconvenience. Excrement dropped by animals and waste thrown out windows by humans was ground into the dirt or the gaps between stones, spreading diseases such as cholera, typhoid, and dysentery through direct contact and contaminated water supplies.
Cities made major strides in paving roads during the last two decades of the nineteenth century. Brick was widely used beginning in the mid-1880s, especially in midwestern cities. Philadelphia had the highest number of bricks in 1898—2 million square yards—although Des Moines, Columbus, and Cleveland claimed more bricks per capita. Asphalt, already widely used in London and Paris, became a popular paving surface after the discovery of natural beds of pitch in Trinidad, and U.S. cities had 30 million square yards of asphalt paving in 1898. By 1900, after two decades of intensive improvements, Washington, D.C. boasted that it was the best-paved city in the world, and other U.S. cities, especially those along the East Coast, made similar claims.
Rural Roads Before 1900
The first rural routes were one-foot-wide paths traced by deer, buffalo, and other animals, or tamped down by Native Americans on foot. Pioneers of European heritage introduced horses and wheeled vehicles to the trails. Colonial governments, beginning with the Massachusetts General Court in 1639, laid out roads between towns, but few were actually constructed, and most long-distance travel in colonial times was by boat.
The most ambitious road project in the colonial era was the 1,300-mile King's Highway between Boston and Charleston, South Carolina, linking all thirteen colonies. The stretch between Boston and New York opened in 1673, and was widely known as the Boston Post Road because the route was used for postal delivery. Four years earlier, a post road had been opened from New York to Albany, and several others were constructed during the late seventeenth century to carry mail between the colonies. The entire King's Highway was completed in 1750.
Regular service to carry passengers and goods by horse-drawn covered wagon was inaugurated along the King's Highway and other Post Roads in the years immediately before independence. The fastest service, called the "flying machine," took only a day and a half between Philadelphia and New York during the 1770s, but most intercity travel was difficult: the first regularly scheduled stagecoach route between New York and Boston in 1772 took one week, and it took George Washington twelve days to ride from Philadelphia to Boston to take command of the American army.
Fur traders and other European-descendent travelers to the West also followed paths created by animals and Native Americans. European Americans carved out new trails in the interior during the 1770s, including the Watauga Road from Virginia's Shenandoah Valley to east Tennessee in 1773, and the
Road building into the interior was extensive in the years immediately after independence, as the new country sought to tie together disparate colonies and a vast frontier. Lacking money to build and maintain roads, states turned to private companies beginning in 1790, when Pennsylvania offered a charter to the Philadelphia and Lancaster Turnpike Company. The company started building a road in 1792 and in 1794 opened the first sixty-two miles. The road was called a turnpike because a gatekeeper turned a pole armed with pikes to permit travelers to pass through after paying the toll.
When the Philadelphia and Lancaster Turnpike proved profitable, it was later extended further west, and hundreds of charters were awarded to turnpike companies by Pennsylvania and other states. Turnpike authorities were typically authorized to erect tollgates every five to ten miles and to charge ten to twenty-five cents. Tolls were used to pay for construction and maintenance.
The turnpike era culminated with the construction of the National Pike, authorized by Congress in 1806. The first 130-mile stretch between Cumberland, Maryland and Wheeling, West Virginia, known as the Cumberland Road, followed a narrow dirt trail known as Nemacolin's Path, created around 1750 by the Delaware Indian chief Nemacolin and Colonel Thomas Cresap. Contracts were given out in 1811, but the War of 1812 delayed the start of construction until 1815, and it was completed in 1818. The National Pike was later extended across Ohio and Indiana and terminated in Vandalia, Illinois. A planned extension to Jefferson City, Missouri, was not built.
The Cumberland Road and other early turnpikes were constructed of crushed stone, but the rest of the National Pike and other later turnpikes were surfaced with macadam, named for Scottish engineer John McAdam, in which a layer of compacted small stones was cemented into a hard surface by stone dust and water. Wetlands and small streams were crossed by placing logs side by side, a style known as corduroy.
Taking advantage of the well-built turnpikes, large heavy vehicles that would have become stuck on dirt roads were placed in service beginning in the 1820s. Concord coaches, pulled by a team of four to six horses, were built in three sizes—six, nine, and twelve passenger coaches—while Conestoga wagons, pulled by six to eight horses, carried freight. A dozen stagecoach lines carried passengers along the National Pike from Washington, D.C. to Wheeling in thirty hours, to Columbus, Ohio in forty-five hours, and to Indianapolis, Indiana in sixty hours.
Rural road construction came to a halt in the United States in the face of competition from canals and especially railroads. Many of the turnpike companies went bankrupt during the 1840s, and the roads deteriorated through neglect during the second half of the nineteenth century. Plank roads, made of wood, were constructed during the 1840s, but these quickly decayed and were not repaired.
Roads in the Automotive Age
The United States had the world's most extensive railroad network in 1900—and some of the world's worst roads. Through the twentieth century, road construction and motor-vehicle ownership reinforced each other. As motor-vehicle sales grew rapidly—exceeding 1,000 for the first time in 1899, 100,000 in 1909, and 1 million in 1916—Americans demanded and got good roads. At the same time, road construction stimulated increased usage of motor vehicles and, ultimately, dependence on them.
When the Office of Public Roads Inquiries undertook the first inventory of all U.S. roads in 1904, the country had 2,151,570 miles of rural public roads, but 1,997,908 miles, or 93 percent, were dirt. Of the 153,662 miles with any kind of surfacing, only 38,622 miles were stone or macadam, while the remainder included 108,232 miles of gravel and 6,810 of shell, sand, clay, brick, or other materials. Only a few hundred miles of roads in the entire country were suitable for motor vehicles.
A majority of Americans still lived in rural areas in the early twentieth century, but operating a motor vehicle there was nearly impossible because of poor-quality—or nonexistent—roads. Consequently, most vehicles were purchased by people living in cities, where streets were paved. Roads in rural areas served primarily as feeders into train stations. A few miles from stations, roads would terminate at streams or county lines or simply disappear into the mud. The cost of hauling grain ten miles from farm to station by road was higher than the cost of hauling it five hundred or one thousand miles by train to big-city markets. It could take an entire day to travel twenty miles in a rural area.
Good Roads Movement
Bicycling was booming as a leisure activity in 1900, and cyclists demanded good roads. The United States had 18 million horses in 1900, and many of their owners also demanded good roads. Bicycle and buggy owners were soon joined by millions of owners of Model Ts, produced on the Ford Motor Company's moving assembly line and sold at a price that was affordable for most American households.
Several organizations pushed for good roads. The League of American Wheelmen founded Good Roads Magazine in 1892 to promote the need for public roads. The National League of Good Roads lobbied for trained engineers to supervise road construction and educated farmers on the benefits of good roads. The National Good Roads Convention in St. Louis in 1903 heard President Theodore Roosevelt declare that a people who could tame a continent should be able to build good roads. In 1919 Colonel Dwight Eisenhower led an army convoy through the West to demonstrate the poor quality of roads and the resulting adverse impact on national security.
For motor vehicle owners, a top priority was construction of a highway linking the East and West Coasts. In the absence of public funding for highway construction, Indianapolis Motor Speedway owner Carl Fisher led a campaign to finance through private contributions the construction of a coast-to-coast highway named the Lincoln Highway, as a memorial to the slain president. For example, to promote the use of cement in highway construction, the Lehigh Cement Company donated 1.5 million barrels (the first cement highway was poured in Michigan in 1908). The Lincoln Highway was completed in 1923.
New Jersey was the first state to finance road construction through taxes, in 1891. Similar legislation was enacted by Massachusetts and Virginia a year later, and in twenty-seven states by 1913. Massachusetts and New York were the only two states collecting license fees from car owners in 1903.
At the federal level, the Office of Road Inquiry (later the Office of Public Road Inquiries, and then the Office of Public Roads) was established in 1893 in the U.S. Department of Agriculture. But the federal government did not fund rural road construction until the 1916 Federal Aid Road Act. The act appropriated $75 million over five years to pay half of the cost of building rural post roads, up to $10,000 per mile (later raised to $20,000 per mile). States had to agree to pay the remaining half, maintain them, and keep them free of tolls. The amount of surfaced roads in the United States increased from 257,291 miles in 1914 to 521,915 miles in 1926. When the system was completed during the 1930s, 90 percent of the population lived within ten miles of a Federal Aid road.
The Federal Highway Act of 1921 called for the designation of a national highway system of interconnected roads. No more than 7 percent of a state's public roads could be included in the system. The complete national system of 96,626 miles was approved in 1926 and identified by the U.S. highway numbers still in use. The Boston Post Road became part of U.S. 1, the Lincoln Highway part of U.S. 30, and the National Pike part of U.S. 40.
Limited-access parkways modeled on the German autobahn highways were built during the 1930s. The New York metropolitan area had a particularly large number of parkways, thanks to longtime parks commissioner Robert Moses, who wanted motorists to have access to the beaches of Long Island and the forests of Westchester County. Envisioning the New York parkways as for recreational driving only, Moses had the clearances under the bridges crossing the parkways designed too low for trucks. The Arroyo Seco Parkway (now the Pasadena Freeway), the first modern freeway in the Los Angeles area, opened in 1940, as did the Pennsylvania Turnpike, the first long-distance limited-access highway through rural areas. Toll roads were built throughout the Northeast between Maine and Illinois in the years immediately after World War II.
Federal interest in limited-access highways dates from the 1938 Federal Aid Highway Act, which proposed a 26,700-mile national system. The 1944 Federal Aid Highway Act expanded the proposed system to 40,000 miles, and the 1952 Federal Aid Highway Act provided the first token appropriation for their construction.
The landmark legislation was the Federal Aid Highway Act of 1956, which established a 44,000-mile toll-free National System of Interstate and Defense Highways and committed the federal government to pay 90 percent of the cost. Most of the miles of interstate highways were constructed to connect cities, but most of the dollars were spent to cross inside cities.
Impact of Interstate Highways
The trucking industry especially benefited from the interstate highways. Rail and truck shared in the growth of freight handling during the first half of the twentieth century about evenly, railroads going from 896 million tons in 1906 to 1.4 billion in 1950, and trucks from nil in 1906 to 800 million in 1950. But over the next two decades, after most rural interstate highways were completed, truck haulage more than doubled to 1.9 billion tons, whereas railroads carried 1.5 billion tons, about the same as in 1950. Railroads were relegated to longer-distance hauling.
With construction of the interstate highways, the United States became a nation of suburbanites. The number of Americans living in suburbs increased from 30 million in 1950 to 120 million in 1990, whereas the number in cities of at least 50,000 inhabitants declined from 60 million to 40 million, and the number in rural areas declined from 60 million to 50 million. In 1950, 40 percent of Americans lived in rural areas, 40 percent in cities, and 20 percent in suburbs. A half-century later, after construction of the interstate highways, 20 percent of Americans lived in rural areas, 20 percent in cities, and 60 percent in suburbs.
People drove farther because they needed to do so to reach jobs, shops, and recreation. Taking advantage of the increased speeds afforded by cars, people chose to make longer trips rather than to reduce travel time. The average motorist drove 25 percent more per year in 2000 than in 1950. Average commuting distance increased 15 percent just between 1950 and 1960, offsetting a 15 percent increase in average speed that decade. Private ownership of cars enabled Americans to move to suburban houses and travel to shops, jobs, and entertainment downtown. Soon the shops, jobs, and entertainment moved to the suburbs, where most of the people lived.
Interstate highways enabled more Americans to drive many more vehicles many more miles on a few more roads, and suburbanization required them to do so. In 1950, 150 million Americans drove 48 million vehicles 458 billion miles on 2 billion miles of paved roads. A half-century later, 250 million Americans drove 201 million vehicles 2.4 trillion miles on 4 billion miles of paved roads. Thus the number of Americans increased by two-thirds, the number of roads doubled, the number of vehicles quadrupled, and the number of miles driven increased six-fold.
Roads in the Twenty-First Century
Faced with the difficulty of increasing capacity through new road construction, engineers tried to ease congestion in the early twenty-first century by making more efficient use of existing highways through designating carpool lanes, building park-and-ride lots, and encouraging employers to stagger work hours. Technological improvements further helped traffic flow. A navigation system in the vehicle, receiving continuously updated traffic data from satellites, alerted the driver to traffic jams and suggested alternate routes. Heavily used freeways were reconstructed with sensors in the pavement that could in the future control speed and distances between vehicles by regulating acceleration, braking, and steering.
Demand was also reduced by charging motorists for the use of existing roads and building new toll roads. Private or special-purpose public agencies gained authorization to construct new freeways during the 1990s, much as railroad companies did a century earlier and turnpike companies two centuries earlier. The California Private Transportation Company built a four-lane highway in Orange County parallel to the congested eight-lane Riverside Freeway (CA 91) between CA 55 on the west and the Riverside County line on the east. The company offered a money-back guarantee that the road would be congestion-free. The promise was kept by changing the toll by time of day, perhaps 25 cents at night and $4 during rush hour. A sign at the entrance to the road announced the cost at that moment to use the road. As the traffic volume increased, the cost was raised until sufficient motorists had chosen the old free road to maintain congestion-free driving on the toll road. Motorists could use the toll road only if they had purchased in advance windshield transponders that recorded the fares then in effect. Tolls were collected through monthly statements based on the records generated by the transponders rather than at tollbooths. Vehicles entering the road without transponders were noted by a sensor, and tickets of at least $100 were issued, either in person by highway patrol officers or through the mail.
Despite the wide variety of available technological strategies, congestion persisted, primarily because most Americans did not behave the way traffic engineers and economists thought they "should." In the 1950s, planners conducted elaborate studies to determine the optimal locations for new roads in response to travel demand patterns. The location of residences, shops, offices, and entertainment centers generated measurable amounts of traffic at specific times of the day. New roads were situated to accommodate existing and projected demand.
Ignored in the planning was the reciprocal relationship between roads and land uses. Roads were located in response to changing land uses, but in reality they also caused changing land uses. A highway built in the middle of nowhere soon sprouted commercial establishments and residential subdivisions near the interchanges. Engineers learned that if they built roads, motorists would come.
Bibliography
Flink, James J. The Automobile Age. Cambridge, Mass.: MIT Press, 1988.
Garrison, William L., et al. Studies of Highway Development and Geographic Change. New York: Greenwood Press, 1969.
Goddard, Stephen B. Getting There: The Epic Struggle Between Road and Rail in the American Century. New York: Basic Books, 1994.
Hart, Virginia. The Story of American Roads. New York: Sloane, 1950.
Hokanson, Drake. The Lincoln Highway: Main Street Across America. Iowa City: University of Iowa Press, 1988.
Holbrook, Stewart Hall. The Old Post Road: The Story of the Boston Post Road. New York: McGraw-Hill, 1962.
Jordan, Philip D. The National Road. Indianapolis, Ind.: Bobbs-Merrill, 1948.
Kaszynski, William. The American Highway: The History and Culture of Roads in the United States. Jefferson, N.C.: McFarland, 2000.
Patton, Phil. Open Road: A Celebration of the American Highway. New York: Simon and Schuster, 1986.
Rae, John B. The Road and the Car in American Life. Cambridge, Mass.: M.I.T. Press, 1971.
Rubenstein, James M. Making and Selling Cars: Innovation and Change in the U.S. Automotive Industry. Baltimore: Johns Hopkins University Press, 2001.
The Roman roads, however, are famous. In Italy and in every region that the Romans conquered, they built roads so durable that parts of them yet remain serviceable. The Roman roads were generally straight, even over steep grades. The surface, made of large slabs of hard stone, rested on a bed of smaller stones and cement about 3 ft (91 cm) thick.
From the fall of the Roman Empire until the 19th cent., European roads generally were neglected and hard to travel. People usually walked, rode horses, or were carried in sedan chairs. Goods were transported by pack animals. In France, Louis XIV and Napoleon built good roads for military purposes. Elsewhere on the Continent roads were not much improved before the middle of the 19th cent. In Great Britain two Scottish engineers, Thomas Telford and John L. McAdam, were responsible for the development of the macadam road (see pavement). The expansion of the Industrial Revolution brought this and other road improvements to the Continent, although the emphasis was on railroad construction until after the invention of the automobile.
In the Americas the Inca empire was remarkable for its fine roads. In what is now the United States, however, the waterways were the normal mode of travel for Native Americans, and their trails, though numerous, were often simply footpaths. These were used by white settlers and were eventually widened to make wagon trails. The increasing use of stagecoaches led to some improvement, and the turnpike, or toll road, was introduced at the beginning of the 19th cent. Although the planning and building of road arteries, notably the National Road, marked the early years of the century, canals and then railroads took precedence.
The invention and mass production of the automobile made the road became paramount again. Hard-surfaced highways were stretched across the entire land in a relatively few years. The building of roads became a major branch of engineering, and even the most difficult obstacles were surmounted. Roads have helped greatly to equalize and unify large heterogeneous nations. In the United States the Interstate Highway System consists of 42,793 mi (68,869 km) of roads (all but a few miles of which are completed) connecting every major city. Other well-known road networks which serve to unify large areas include Germany's Autobahn, the Trans-Canada Highway, and the Pan-American Highway. An ambitious, 23-nation agreement to link Asia with a network of highways was signed in 2004.
Bibliography
See L. J. Ritter and R. J. Paquette, Highway Engineering (1967); G. Hindley, A History of Roads (1972).
Related to animals on roadways.
n.
A strip of land along which one may pass from where it is too tiresome to be to where it is futile to go.
All roads, howsoe'er they diverge, lead to Rome,
Whence, thank the good Lord, at least one leads back home.
Borey the Bald
Sometimes the road less traveled is less traveled for a reason.
— Jerry Seinfeld
A road is an identifiable route, way or path between two or more 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[3]. In urban areas roads may pass through a city or village and be named as streets, serving a dual function as urban space easement and route.[4] 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. [5]
In original usage, a "road" was simply any pathway fit for riding. The word “street,” whose origin is the Latin strata, was kept for paved pathways that had been prepared to ease travel in some way. Thus, many "Roman Roads" have the word "street" as part of their name.[6][7] Roads are a prerequisite for road transport of goods on wheeled vehicles[6].
Words with related usage include, Avenue, Boulevard, Court, Drive, Freeway, Highway, Lane, Street, Turnpike and Way.
That the first pathways were the trails made by animals has not been universally accepted, arguing that animals do not follow constant paths. [8] Others believe that some roads originated from humans following animals trails.[9][10] The Icknield Way is given as an example of this type road origination were man and animal both selected the same natural line.[11] By about 10,000 BC, rough pathways were used by human travelers. [8]
"#wp-_note-Discovering_Roman_Technology">[16] 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. [6]
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.[18]
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
Road building and maintenance is an area of economic activity that remains dominated by the public sector (though often through private contractors).[19] Roads (except those on private property not accessible to the general public) are typically paid for by taxes (often raised through levies on fuel),[20] though some public roads, especially highways are funded by tolls.[21]
Prior to the advent of the internal combustion engine, a principal environmental effect was production of animal excrement from horses, cattle and other animals on drovers' roads and other streets. In the 19th century this issue became significant enough to have some European city officials call for more cleanliness on the roads. [citation needed] Beginning in the 20th century the excrement issue has been overshadowed by vehicle production of noise and air pollution emissions. [citation needed]
Motor vehicle traffic on roads generate noise pollution especially at higher operating speeds. 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.[22]
Motor vehicles operating on roads contribute emissions, particularly for congested city street conditions and other low speed circumstances. Concentrations of air pollutants and adverse respiratory health effects are greater near the road than at some distance away from the road. [23]
Traffic flows on the right or on the left side of the road depending on the country.[24] 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, and pedestrians crossing a two-way road should watch out for traffic from the left first.[25] 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,[26] even though originally most traffic drove on the left worldwide.[27]
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.[28] (pg15) and may be required to meet standards set by law[29] or official guidelines.[30] 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.[31] [32]
After design, approval, planning, legal and environmental considerations have been addressed alignment of the road is set out by a surveyor. [16] The Radii and gradient are designed and staked out to best suit the natural ground levels and minimize the amount of cut and fill.[30] (page34) Great care is taken to preserve reference Benchmarks [30](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. [30] (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. [30] (page 53 to 56 )
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 maybe 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.[30] (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.[30] (page 68 to 69 )
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. [30] (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.
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[33] 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.
Sometimes, the new carriageway may be constructed along one side of the existing carriageway for some distance, then constructed on the opposite side. When this occurs, the existing carriageway is split and joined to the new sections, with a short section of the old carriageway being torn up and turned into median.
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.[34] 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.[35] A typical tractor-trailer weighing 80,000 pounds with 8,000 pounds on the steer axle and 36,000 pounds on both of the tandem axle groups is expected to do 7,800 times more damage than a passenger vehicle with 2,000 pounds on each axle.
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. [36] 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 1950's have significantly outlived their intended design lives. [37] 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. [38]
Virtually all roads require some form of maintenance before they come to the end of their service life. Maintenance treatments for asphalt concrete generally include crack sealing, surface rejuvenating, fog sealing, micro-milling and thin surfaceings. 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.[39]