Roads and highways

Roads and highways, traveled way on which people, animals, or wheeled vehicles move. In modern usage the term road describes a rural, lesser traveled way, while the word street denotes an urban roadway. Highway refers to a major rural traveled way; more recently it has been used for a road, in either a rural or urban area, where points of entrance and exit for traffic are limited and controlled.

Dubai, United Arab Emirates: Sheikh Zayed Road

The most ancient name for these arteries of travel seems to be the antecedent of the modern way. Way stems from the Middle English wey, which in turn branches from the Latin veho (“I carry”), derived from the Sanskrit vah (“carry,” “go,” or “move”). The word highway goes back to the elevated Roman roads that had a mound or hill formed by earth from the side ditches thrown toward the centre, thus high way. The word street originates with the Latin strata (initially, “paved”) and later strata via (“a way paved with stones”). Street was used by the Anglo-Saxons for all the roads that they inherited from the Romans. By the Middle Ages, constructed roads were to be found only in the towns, and so street took on its modern limited application to town roads. The more recent word road, derived from the Old English word rád (“to ride”) and the Middle English rode or rade (“a mounted journey”), is now used to indicate all vehicular ways.

Modern roads can be classified by type or function. The basic type is the conventional undivided two-way road. Beyond this are divided roads, expressways (divided roads with most side access controlled and some minor at-grade intersections), and freeways (expressways with side access fully controlled and no at-grade intersections). An access-controlled road with direct user charges is known as a tollway. In the United Kingdom freeways and expressways are referred to as motorways.

Functional road types are local streets, which serve only adjacent properties and do not carry through traffic; collector, distributor, and feeder roads, which carry only through traffic from their own area; arterial roads, which carry through traffic from adjacent areas and are the major roads within a region or population centre; and highways, which are the major roads between regions or population centres.

The first half of this article traces the history of roads from earliest times to the present, exploring the factors that have influenced their development and suggesting that in many ways roads have directly reflected the conditions and attitudes of their times. The road is thus one of the oldest continuous and traceable metaphors for civilization and society. The second half of the article explains the factors behind the design, construction, and operation of a modern road. It is shown that a road must interact closely and carefully with the terrain and community through which it passes, with changing vehicle technology, with information technologies, and with the various abilities, deficiencies, and frailties of the individual driver.

History

Roads of antiquity

Ancient roads of the Mediterranean and Middle East

The first roads were paths made by animals and later adapted by humans. The earliest records of such paths have been found around some springs near Jericho and date from about 6000 BC. The first indications of constructed roads date from about 4000 BC and consist of stone-paved streets at Ur in modern-day Iraq and timber roads preserved in a swamp in Glastonbury, England. During the Bronze Age, the availability of metal tools made the construction of stone paving more feasible; at the same time, demand for paved roads rose with the use of wheeled vehicles, which were well established by 2000 BC.

Cretan stone roads

At about this time the Minoans on the island of Crete built a 30-mile (50-kilometre) road from Gortyna on the south coast over the mountains at an elevation of about 4,300 feet (1,300 metres) to Knossos on the north coast. Constructed of layers of stone, the roadway took account of the necessity of drainage by a crown throughout its length and even gutters along certain sections. The pavement, which was about 12 feet (360 centimetres) wide, consisted of sandstone bound by a clay-gypsum mortar. The surface of the central portion consisted of two rows of basalt slabs 2 inches (50 millimetres) thick. The centre of the roadway seems to have been used for foot traffic and the edges for animals and carts. It is the oldest existing paved road.

Roads of Persia and Babylon

The earliest long-distance road was a 1,500-mile route between the Persian Gulf and the Mediterranean Sea. It came into some use about 3500 BC, but it was operated in an organized way only from about 1200 BC by the Assyrians, who used it to join Susa, near the Persian Gulf, to the Mediterranean ports of Smyrna (İzmir) and Ephesus. More a track than a constructed road, the route was duplicated between 550 and 486 BC by the great Persian kings Cyrus II and Darius I in their famous Royal Road. Like its predecessor, the Persian Royal Road began at Susa, wound northwestward to Arbela, and thence proceeded westward through Nineveh to Harran, a major road junction and caravan centre. The main road then continued to twin termini at Smyrna and Ephesus. The Greek historian Herodotus, writing about 475 BC, put the time for the journey from Susa to Ephesus at 93 days, although royal riders traversed the route in 20 days.

In Babylon about 615 BC the Chaldeans connected the city’s temples to the royal palaces with the Processional Way, a major road in which burned bricks and carefully shaped stones were laid in bituminous mortar.

Egypt

Herodotus credits the Egyptians with building their first roads to provide a solid track upon which to haul the immense limestone blocks used in the pyramids, and archaeological evidence indicates that such road building took place southwest of Cairo between 2600 and 2200 BC. The wheel arrived in Egypt at the relatively late date of about 1600 BC. There is little evidence of street surfacing in ancient Egyptian towns, though there is evidence of the use of paved processional roads leading to the temples. The ancient travel routes of Egypt ran from Thebes and Coptos on the central Nile east to the Red Sea and from Memphis (Cairo) across the land bridge to Asia Minor.

Greece

The early Greeks depended primarily on sea travel. There is evidence of the building of special roads for religious purposes and transport about 800 BC, but there is little evidence of substantial road building for travel and transport prior to the Roman system. The Greeks did build a few ceremonial, or “sacred,” roads, paved with shaped stone and containing wheel ruts about 55 inches (140 centimetres) apart.