This term is also often used to refer to natural waterways, which are used by shipping. Famous examples are Hampton Road in Virginia and Castle Road in Bermuda (formerly in Virginia).
In urban areas, roads may pass through a city or village and be named streets, which have the dual functions of urban space convenience and roads. [4] Economy and society depend on efficient roads to a great extent. In the European Union (EU ), 44% of goods are transported by truck and 85% of people are transported by car, bus or coach.
The United States has the largest road network in the world, with a total length of 6,430,366 kilometers (2005). India has the second largest highway system in the world, with a total length of 3383344 kilometers (2002). People's Republic of China (PRC) ranked third with the road length of 1, 870,661km (2004). [6] If we only look at expressways, the total length of People's Republic of China (PRC)'s National Trunk Highway System (NTHS) was 45,000 kilometers at the end of 2006, second only to the United States' 90,000 kilometers in 2005. [
Usage and etymology
In its original usage, "road" is any path suitable for riding. The word "street" originated from the stratum in Latin America, and was reserved for paved roads prepared to facilitate travel in some way. Therefore, many "Roman roads" have the word "street" in their names. [9][ 10] Road is a prerequisite for wheeled vehicles to transport goods by road.
Words with related usages include Avenue, Boulevard, Court, Drive, Freeway, Highway, Lane, Parkway, Path, Street, toll road and way.
history
The original path is the trace left by animals, which has not been generally accepted that animals will not follow a fixed path. Others think that some roads originated from people following the footsteps of animals. Icknield Road is an example. People and animals of this type of road have chosen the same natural route. Around10,000 BC, human travelers used rough roads.
Historical road buildings dating back to 4000 BC
Streets paved with stones can be traced back to the Middle East city of Ur in 4000 BC.
The corduroy road (log road) in 4000 BC was discovered in Glastonbury, England.
Wood track; Sweet track causeway in England is one of the oldest engineering roads found, and it is also the oldest timber track found in Northern Europe. Tree-ring dating (dendrochronology), which was established in the winter of 3807 BC or the spring of 3806 BC, makes it possible to date trees very accurately. It is considered to be the oldest road in the world.
Brick streets were used in India as early as 3000 BC.
In 500 BC, Darius I the Great built a huge highway system for Persia, including the famous Royal Highway, which was one of the best highways at that time. This road has been in use since Roman times.
In ancient times, river transportation was much easier and faster than road transportation, especially considering the cost of road construction and the difference in carrying capacity between carts and river barges. From about 1740, the mixture of road transportation and ship transportation is a horse-drawn boat. On the boat, the horse moves along a clean path along the river bank.
From about 3 12 BC, the Roman Empire built straight and solid stone Roman roads throughout Europe and North Africa to support its military operations. At its peak, the Roman Empire was connected by 29 main roads extending from Rome, covering 78,000 kilometers or 52,964 Roman miles of paved roads.
In 1600, road construction and maintenance in Britain were traditionally carried out on the basis of local parishes. This has led to poor and changeable road conditions. In order to remedy this, the first "Toll Road Trust" was about 1706, which was used to build good roads and collect tolls from passing vehicles. Finally, there are about 1, 100 trust companies and about 36,800 kilometers of engineering roads in Britain. 1839 to 1844 Rebecca riots in Carmarthenshire and Rhayader contributed to the emergence of the Royal Commission and the demise of the system in 1844.
Road transport economics
Main article: transport economics.
Transportation economics is a branch of economics, and the study of resource allocation in transportation sector is closely related to civil engineering. Transportation economics is different from other branches of economics, because the assumption of no space and instantaneous economy is not established. People and goods flow on the network at a certain speed. Demand peaked. Buying tickets in advance is often induced by lower fares. The network itself may or may not be competitive. A trip (the final product from the consumer's point of view) may need to bundle the services provided by several companies, institutions and models.
Although the transportation system follows the same theory of supply and demand as other industries, the complexity of network effect and the choice between dissimilar goods (such as car and bus travel) make it difficult to estimate the demand for transportation facilities. The development of models to estimate the possible choices between dissimilar goods involved in transportation decision-making "Discrete choice" model led to the development of an important branch of econometrics and the Nobel Prize in Daniel McFadden.
In transportation, the demand can be measured by the number of trips or the total distance of all trips (for example, passenger kilometers in public transportation or vehicle kilometers in private transportation (VKT)). Supply is considered as a measure of production capacity. The price of goods (travel) is measured by the generalized travel cost, including money and time expenditure. The impact of increased supply (capacity) is particularly important in transport economics (see induced demand) because the potential environmental consequences are significant.
Road construction and maintenance is an area of economic activity that is still dominated by the public sector (although usually through private contractors). Roads (except those on private property that are inaccessible to the general public) are usually paid by taxes (usually raised by collecting fuel taxes), although some public roads, especially highways, are funded by tolls.
[Environmental aspects]
Motor vehicle traffic on the road produces noise pollution, especially at high speed. Therefore, it is expected that the road system used by a large number of motor vehicles will have a considerable noise health impact. Noise mitigation strategy aims to reduce the sound level of nearby sensitive receptors. The idea that road design will be influenced by acoustic engineering considerations first appeared in 1973.
Motor vehicles driving on roads will produce emissions, especially in crowded urban street conditions and other low-speed situations. The concentration of air pollutants near the road and its adverse effects on respiratory health are greater than those far away from the road.
Drive right or left?
Depending on the country, vehicles drive on the right or left side of the road. [26] In countries where traffic drives on the right, most traffic signs are on the right side of the road, and the roundabout and traffic circle are counterclockwise. Pedestrians crossing two-way roads should first pay attention to the vehicles on the left. In countries where traffic drives on the left, the situation is just the opposite.
According to the population, about 34% people in the world drive on the left and 66% people drive on the right. As far as road distance is concerned, about 28% people drive on the left and 72% drive on the right [28], although at first most of the traffic in the world drove on the left.
build
Road construction needs to establish a continuous right of way, overcome geographical obstacles, and have a low enough slope to allow vehicles or pedestrians to pass, and may need to meet the standards stipulated by laws or official guidelines. This process usually begins with the removal of soil and rocks by excavation or blasting, the construction of embankments, bridges and tunnels, and the removal of vegetation (which may involve deforestation), and then the laying of pavement materials. All kinds of road construction equipment are used in road construction.
After the design, approval, planning, legal and environmental considerations are solved, the road alignment will be carried out by the surveyor. The design and selection of radius and slope should be most suitable for natural ground height, and the amount of excavation and filling should be minimized. Save the reference datum very carefully.
The design and construction of roads are mainly used for vehicle and pedestrian traffic. Rainstorm drainage and environmental considerations are the main concerns. Erosion and sediment control are designed to prevent harmful effects. The drainage pipeline is laid at the sealed joint of the road relaxation zone, which has the r unoff coefficient and characteristics suitable for land division and rainwater system. The drainage system must be able to carry the final design flow from the upstream catchment, and obtain the permission of the relevant authorities to discharge into waterways, streams, rivers or oceans for drainage.
Borrow pits (sources of fillers, gravels and rocks) and water sources should be located near the road construction site or within a reasonable distance. It may be necessary to obtain approval from local authorities to extract water or carry out material processing (crushing and screening) required for construction. Remove topsoil and vegetation from the borrow pit and pile them up for the subsequent restoration of the ex traction area. For safety reasons, the slope gradient in the excavation area shall not exceed one vertical to two levels.
Old pavements, fences and buildings may need to be demolished before construction begins. Trees in the road construction area can be reserved. These protected trees should not remove the topsoil in drip line area, and the area should be kept free of building materials and equipment. If the protected trees are damaged, they may need to be compensated or replaced. Many plants may be covered and put aside for irrigation. Topsoil is usually stripped and stacked nearby for the repair of new embankments along the road. Before the earthwork starts, remove stumps and roots as needed and fill holes. The final restoration after the completion of road construction will include sowing, planting, watering and other activities to restore the area and make it consistent with the surrounding unaffected areas.
Earthwork processes include excavation, material removal, filling, compaction, construction and finishing. If rocks or other unsuitable materials are found, remove them, control the moisture content, replace them with standard fillers, and compact them to a relative compactness of 90%. Blasting rocks in subgrade is usually discouraged. When it is necessary to fill the depression to reach the road slope, compact the primary layer after removing the topsoil. Filling is carried out by "compaction layer method", in which a layer of filler is spread out and then compacted to the specified requirements, and the process is repeated until the required slope is reached.
Generally, the filling material should contain no organic matter, conform to the lowest California bearing ratio (CBR) and have a low plasticity index. The selected filler (sieve) should be composed of gravel, decomposed rock or broken rock with a particle size below the specified size, and it does not contain large clay. Sand clay filler can also be used. After each layer of filler is compacted, the subgrade must be "certified rolled". If there is no visible deformation or elasticity when the roller passes through an area, the part is considered to meet the requirements.
The completed road is paved or left with gravel or other natural surfaces. The type of pavement depends on economic factors and the intended use. Safety improvement measures such as traffic signs, crash barriers, raised road signs and other forms of road signs have been installed.
copy
When a one-lane road is converted into a two-lane road by building a second separate lane next to the first lane, it is usually called a double lane or a two-lane road. The original carriageway is changed from two-way to one-way, while the new carriageway is one-way in the opposite direction. Like changing a railway line from a single lane to a double lane, new lanes are not always built directly along the existing lanes.
maintain
Like all structures, roads will deteriorate over time. The deterioration is mainly due to the cumulative damage of vehicles, but environmental influences, such as frost, thermal cracking and oxidation, often play a role. According to a series of tests (called AASHO road test) conducted in the late 1950s of/KLOC-0, it is determined from experience that the effective damage to roads is roughly proportional to the 4th power of axle load. A typical tractor trailer weighs 80,000 pounds (36.287 tons), the steering shaft weighs 8,000 pounds (3.6287 tons), and the two tandem axle groups weigh 36,000 pounds (16.329 tons). The estimated damage degree is 2,000 pounds (0) on each axle.
pothole
Pavement is designed for expected service life or design life. In some British countries, the standard design life of new asphalt and concrete pavements is 40 years. During the milestone service periods of 10, 20 years and 30 years, maintenance is considered in the whole life cost of the road. Roads can be designed for various service lives (8-year, 65-year, 30-year and 60-year designs). When the service life of pavement exceeds its expected life, it may be overbuilt and the original cost may be too high. When the pavement breaks down before its expected design life, the owner may have too much repair and restoration costs. Many concrete pavements built since 1950 have greatly exceeded their expected design life. [39] Some roads, such as "Wacker Drive" in Chicago, Illinois, a major urban two-story viaduct is being rebuilt, and its designed service life is 100 years.