History of road transport

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The history of road transport started with the development of tracks by humans and their beasts of burden.

Contents

[edit] Early roads

The first forms of road transport were horses, oxen or even humans carrying goods over tracks that often followed game trails, such as the Natchez Trace.[1] In the Stone Age humans need not need constructed tracks in open country and the first improved trails would have been at fords, mountain passes and through swamps.[2] The first improvements would have consisted largely of clearing trees and big stones from the path. As commerce increased, the tracks were often flattened or widened to accommodate human and animal traffic. Some of these dirt tracks were developed into fairly extensive networks, allowing communications, trade and governance over wide areas. The Incan Empire in South America and the Iroquois Confederation in North America, neither of which had the wheel, are examples of effective use of such paths.

The first goods transport was on human backs and heads, but the use of pack animals, including donkeys and horses, developed during the Stone Age. The first vehicles is believed to have have been the travois, a frame used to drag loads, which probably developed in Eurasia after the first use of bullocks (castrated cattle) for pulling ploughs. In about 5000 BC, sleds developed, which are more difficult to build than travois, but are easier to propel over smooth surfaces. Pack animals, ridden horses and bullocks dragging travois or sleds require wider paths and higher clearances than people on foot and improved tracks were required.[3] As a result by about 5000 BC road developed along the tops of ridge in England, including the Ridgeway, to avoid crossing rivers and bogging.[4]

[edit] Harappan roads

Street paving has been found from the first human settlements around 4000 BC in cities of the Indus Valley Civilization on the Indian subcontinent, such as Harrapa and Mohenjo-daro.

[edit] Wheeled transport

Wheels appear to have been developed in ancient Sumer in Mesopotamia around 5000 BC, perhaps originally for the making of pottery. Their original transport use may have been as attachments to travois or sleds to reduce resistance. It has been argued that logs were used as rollers under sleds prior to the development of wheels, but there is no archeological evidence for this.[5] Most early wheels appear to have been attached to fixed axles, which would have required regular lubrication by animal fats or vegetable oils or separation by leather to be effective.[6] The first simple two-wheel carts, apparently developed from travois, appear to have been used in Mesopotamia and northern Iran in about 3000 BC and two-wheel chariots appeared in about 2800 BC. They were hauled by onagers, related to donkeys.[7]

Heavy four-wheeled wagons developed about 2500 BC, which were only suitable for oxen-haulage, and therefore were only used where crops were cultivated, particularly Mesopotamia.[8] Two-wheeled chariots with spoked wheels appear to have been developed around 2000 BC by the Andronovo culture in southern Siberia and Central Asia. At much the same time the first primitive harness enabling horse-haulage was invented.[9]

Wheeled-transport created the need for better roads. Generally natural materials cannot be both soft enough to form well-graded surfaces and strong enough to bear wheeled vehicles, especially when wet, and stay intact. In urban areas it began to be worthwhile to build stone-paved streets and, in fact, the first paved streets appear to have been built in Ur in 4000 BC. Corduroy roads were built in Glastonbury, England in 3300 BC[10] and brick-paved roads were built in the Indus Valley Civilization on the Indian subcontinent from around the same time. Improvements in metallurgy meant that by 2000 BC stone-cutting tools were generally available in the Middle East and Greece allowing local streets to be paved.[11] Notably, in about 2000 BC, the Minoans built a 50 km paved road from Knossos in north Crete through the mountains to Gortyn and Lebena, a port on the south coast of the island, which had side drains, a 200 mm thick pavement of sandstone blocks bound with clay-gypsum mortar, covered by a layer of basaltic flagstones and had separate shoulders. This road could be considered superior to any Roman road.[12]

[edit] Royal Road

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 was used even after the Roman times. Because of the road's superior quality, mail couriers could travel 2,699 km in seven days.

[edit] Roman roads

With the advent of the Roman Empire, there was a need for armies to be able to travel quickly from one area to another, and the roads that existed were often muddy, which greatly delayed the movement of large masses of troops. To resolve this issue, the Romans built great roads. The Roman roads used deep roadbeds of crushed stone as an underlying layer to ensure that they kept dry, as the water would flow out from the crushed stone, instead of becoming mud in clay soils. The legions made good time on these roads and some are still used millennia later.

On the more heavily traveled routes, there were additional layers that included six sided capstones, or pavers, that reduced the dust and reduced the drag from wheels. The pavers allowed the Roman chariots to travel very quickly, ensuring good communication with the Roman provinces. Farm roads were often paved first on the way into town, to keep produce clean. Early forms of springs and shocks to reduce the bumps were incorporated in horse drawn transport, as the original pavers were sometimes not perfectly aligned.

[edit] New construction methods in the 18th and 19th centuries

Roman roads deteriorated over the Middle Ages because of lack of resources and skills to maintain them, but many continued be used, and some are still partially used today, for instance, parts of England's A1. As states developed and became richer, especially with the Renaissance, new roads and bridges began to be built, often based on Roman designs. Although there were attempts to rediscover Roman methods, there was little useful innovation in road building before the 18th century.

Between 1725 and 1737 General George Wade constructed 250 miles of road and 40 bridges to improve Britain's control of the Scottish Highlands, using Roman road designs with large stones at the bottom and gravel on top, with a typical overall depth of two metres. They were so poorly aligned and steep, according to Thomas Telford, "as to be unfit for the purposes of civil life" and also rough and poorly drained.[13]

[edit] Toll roads

As traffic levels increased in England and roads deteriorated. Toll roads were built by Turnpike Trusts, especially between 1730-1770. It has been claimed that as a result the time taken between London, to York, Manchester or Exeter was cut by two-thirds between 1720 and 1780.[14] Blind Jack Metcalf (1717-1810) built about 300 km (180 miles) of turnpike road between 1753 abd 1810, mainly in Lancashire, Derbyshire, Cheshire and Yorkshire. He understood the importance of good drainage and surfaced his roads with "a compact layer of small, broken stones with sharp edges", rather than the naturally rounded stones traditionally used in European road building. British turnpike builders began to realise the importance of selecting clean stones for surfacing, and excluding vegetable material and clay to make better lasting roads.[15]

Turnpikes were also later built in the United States. They were usually built by private companies under a government franchise. They typically paralleled or replaced routes already with some volume of commerce, hoping the improved road would divert enough traffic to make the enterprise profitable. Plank roads were particularly attractive as they greatly reduced rolling resistance and mitigated the problem of getting mired in mud. Another improvement, better grading to lessen the steepness of the worst stretches, allowed draft animals to haul heavier loads.

[edit] Trésaguet

In France, Pierre-Marie-Jérôme Trésaguet is widely credited with establishing the first scientific approach to road building about the year 1764. He wrote a memorandum on his method in 1775, which became general practice in France. It involved a layer of large rocks, covered by a layer of smaller gravel. The lower layer improved on Roman practice in that it it was based on the understanding that the purpose of this layer (the sub-base or base course) is to transfer the weight of the road and its traffic to the ground, while protecting the ground from deformation by spreading the weight evenly. Therefore, the sub-base did not have to be a self-supporting structure. The upper running surface provided a smooth surface for vehicles, while protecting the large stones of the sub-base. Trésaguet understood the importance of drainage by providing deep side ditches, but he insisted on building his roads in trenches, so that they could be accessed from the sides, which undermined this principle. Well-maintained surfaces and drains protect the integrity of the sub-base and Trésaguet introduced a system of continuous maintenance, where a roadman was allocated a section of road to be kept up to a standard.[16]

[edit] Developments in England

Thomas Telford (1757-1834) also made substantial advances in the engineering of new roads and the construction of bridges. Under his supervision 1,500 km of roads and 1,000 bridges were built in Scotland between 1802 and 1822. He elaborated Trésaguet method by a more complex and costly system of stonework in the subgrade, but his main improvement over Trésaguet was the raising of his roads above the natural level to improve drainage or the drainage of the area around the road.[17]

John Loudon McAdam (1756-1836) designed the first modern highways. He developed an inexpensive paving material of soil and stone aggregate (known as macadam), and he embanked roads a few feet higher than the surrounding terrain to cause water to drain away from the surface. He had noticed in his observations that coaches with narrow, iron-tyred wheels and moving at relatively high speed were causing significant damage to roads, but that areas of small broken stones were most resistant to damage, while the areas that had large surface stones degraded fastest. His solution was to create roads with three layers of stones laid on a crowned subgrade with side ditches for drainage. The first two layers consisted of angular hand-broken aggregate, maximum size 3 inches (75 mm), to a total depth of about 8 inches (200 mm). The third layer was about 2 inches (50 mm) thick with a maximum aggregate size of 1 inch (25 mm). Each layer would be compacted with a heavy roller, causing the angular stones to lock together with their neighbours. It is possible that his initial decision not to use the heavy layer of base stones used by Telford in his subgrade reflected lack of suitable stones, but McAdam quickly saw they were not necessary. In practice, his roads proved to be twice as strong as Telford's roads.[18] He also inisisted on raising the roads to ensure good trainage and flat crowned surfaces, rather than ridges built into the road to encourage drainage.[19]

McAdam was adamantly opposed to the filling of the voids between his small cut stones with smaller material, possibly as a reaction against the use of thes use of poor materials, including soil and vegetable matter, on roads in the past. Nethertheless, in practice road builders began to introduce filler materials such as smaller stones, sand and clay, and it was observed that these roads were stronger as a result. Macadam roads were being built widely in the United States and Australia in the 1820s and in Europe in the 1830s and 1840s.[20]

[edit] Development of paved roads

Various systems had been developed over centuries to reduce washways, bogging and dust in cities, including cobblestones and wooden paving. Tar-bound macadam (tarmac) was applied to macadam roads towards the end of the 19th century in cities such as Paris. In the early 20th century tarmac and concrete paving were extended into the countryside.

Incidentally, bicyclists were among the early campaigners on what was called the Good Roads Movement. Bicycling was an extremely popular recreation among the middle and upper classes in the late 19th century and was more fun on paved roads.

[edit] References

  • Lay, M G (1992). Ways of the World. Sydney: Primavera Press, 401. ISBN 1875368051. 

[edit] Notes

  1. ^ Ley (1992), p5
  2. ^ Ley (1992), p7
  3. ^ Ley (1992), p25
  4. ^ Ley (1992), p9
  5. ^ Ley (1992), p27
  6. ^ Ley (1992), p28
  7. ^ Ley (1992), p28
  8. ^ Ley (1992), p28
  9. ^ Ley (1992), p28
  10. ^ Ley (1992), p51
  11. ^ Ley (1992), p43
  12. ^ Ley (1992), p44
  13. ^ Ley (1992), p72
  14. ^ Huxford, Robert (3 September 2003). How old is that route? (pdf). Institution of Civil Engineers. Retrieved on 2007-01-19.
  15. ^ Ley (1992), p72
  16. ^ Ley (1992), p73-74
  17. ^ Ley (1992), p75
  18. ^ Ley (1992), p77
  19. ^ Ley (1992), p78
  20. ^ Ley (1992), p83

[edit] See also

[edit] External Links

Macadam - Road Building in America

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