Historically many roads were simply recognizable routes without any formal construction or some maintenance.
The Organization for Economic Co-operation and Development (OECD) defines a road as "a line of

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The assertion that the first pathways were the trails made by animals has not been universally accepted; in many cases animals do not follow constant paths. Some believe that some roads originated from following animal trails. The Icknield Way may

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Road design is part of highway engineering. Structural road design is designing a road for the environment in order to extend its longevity and reduce maintenance. The Shell pavement design method is used in many countries for the design of new asphalt roadsides.

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In transport engineering, subgrade is the native material underneath a constructed road.
Road construction requires the creation of an engineered continuous right-of-way or roadbed, overcoming geographic obstacles and having

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Roads that are intended for use by a particular mode of transport can be reallocated for another mode of transport, i.e. by using

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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

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Adverse camber Where a road slopes towards the outside of a bend, increasing the likelihood that vehicles travelling at speed will skid or topple.

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