Who invented roads and bridges

These four major types of roads can be combined into groupings for administrative and funding purposes. One major grouping is the NHS, which comprises the interstate highways and a large number of the high-volume arterial roads.

Although not exclusive, most of the considerations of ecological impacts that occur in subsequent chapters consider the impacts from the first three functional types listed above. As discussed in Chapters 3 and 4 , ecological considerations such as environmental mitigation and simple physical scale vary by road type. Recognizing that a road does not serve traffic needs by itself is basic to the development of any logical highway system.

Travel involves movement through a network of interrelated roads and streets. The movement channels through an efficient hierarchical system that includes lower-order roads that handle short and local trips to higher-order roads that connect regional and interregional traffic and longer trips. In addition to movement, access is a fundamental function of roads.

Federal law requires functional designations of roads in urban and rural areas for funding purposes. This classification is done by state transportation agencies and is mapped and submitted to Federal Highway Administration FHWA to serve as the official record for the federal.

The distinction between rural and urban areas is made using federal census data to create federal-aid and urban-area boundaries WSDOT Urban roads occur in a census area with an urban population of 5, to 49, or in a designated urban area with a population greater than 50, Rural roads are defined as any road not located within the urban-area boundary.

The best known high-speed limited-access highway system is the current interstate highway system. Because of the need to accommodate heavy freight traffic, these roads are the most expensive to build and maintain.

Other types of limited-access highways include some roads within the NHS or some state limited-access roads, such as the New York Thruway. These limited-access state highways are funded and administered under their own sets of legal standards.

Despite important administrative differences, the committee determined that the differences in ecological impacts of different types of limited-access highways are minor. The interstate system accounts for only 1. These statistics also indicate the potential for the interstate system to deliver greater levels of contaminants to air and water than the total miles of interstate roadway would suggest. However, other factors suggest that the contaminant load is not simply proportional to VMT.

For example, vehicles traveling at interstate speeds may emit some pollutants at a lower rate than vehicles operating on local streets. Other federal highway investment, in addition to the interstate highway system, is reflected in components of the NHS. The NHS consists of the many routes with such designations as U. These roads may be high-speed limited-access highways, arterials, or collectors, depending on the location and configuration of the roadway.

The NHS includes urban and rural roads that serve a wide variety of transportation functions. The NHS comprises , miles of roads, 46, of which are interstate highways. The NHS serves major population centers, intermodal transportation facilities, international border crossings, and major travel destinations. It includes the interstate systems, other rural and urban principal arterials, highways that provide access to major intermodal transportation facilities, strategic highway network connectors, and the defense strategic highway network Figure Arterials consist of the interstate highway system, multilane limited-access freeways and expressways, and other road corridors that serve local areas; they also carry substantial statewide or interstate travel volumes.

This system accounts for approximately Collectors connect local streets and roads with arterials. They provide traffic circulation and land access among downtown city centers, industrial and commercial areas, and residential neighborhoods. Collectors provide lower speeds and less mobility for shorter distances than arterials.

Travel represents vehicle miles traveled per year. Source: FHWA The roads and streets functionally classified as local are all those not classified as part of the principal arterial, minor arterial, and collector system.

Local roads and streets primarily provide access to adjacent land and are generally not maintained by a state highway agency. Local functional systems serve only The growth of suburbs, and the spread-out development patterns that come with it, has had a major influence on urban roadway patterns beginning in the s but particularly occurring after World War II.

The layout of the road system is not only a function of history and geography but is also linked to the local and regional development patterns. Layout patterns give roads different types of connectivity.

The layout patterns and spacing among roads as well as their width number of lanes determine road density. There are several types of roadway layouts that are being used for designing roads. These patterns can vary greatly from city to city but generally involve a rectangular grid, a hub-and-spoke layout, or a combination of the two.

The road network in most cities across the United States is an out-growth of the Public Land Surveys and follows a rectangular grid pattern Figure Roads are orthogonal, alignment generally being along ordinal directions north-south or east-west. Grid patterns generally have more total street length, blocks, intersections, and access points than other layouts. The grid pattern is typically intertwined with a mixed pattern of land use.

Mixed land use was the dominant development style in American cities and towns in the early twentieth century and continued to be the primary pattern until the development of suburbs after World War II. A mixed land-use pattern can ease conges-. Source: MapQuest Reprinted with permission; copyright , MapQuest. The MapQuest. It may also reduce the total VMT if housing and services are intermixed. However, it can also add unwanted through traffic on some residential streets Berkovitz In many locations, the hub-and-spoke pattern developed with the local growth pattern in the s and s.

This system of roads comprises circular roads hubs, belts, and ring roads that go around a city center at various distances and separate roads spokes that go to the center of town Figure The circular roads are often used to route traffic around major urban areas, and the spokes are designed for commuter traffic. Freeways and expressways interstate often form the circular hubs and major spokes in urban and suburban areas.

The hub-and-spoke pattern is correlated with a type of land-use pattern that is designated as conventional land use. This pattern arose, in part, because of central urban planning and the increased importance of. Suburban areas grew in number and size to house families. Residential areas are often built with cul de sacs and a small number of entry points to reduce the amount of pass-by traffic in residential neighborhoods Berkovitz In the conventional pattern of land use, each type of land use residential, commercial, retail, and industrial is separated from the others.

Conventional land-use patterns result in more of a hub-and-spoke or circulatory pattern, with businesses in the center of town and residential areas surrounding the city. Some of the longest commutes in metropolitan regions are made by residents who live at the metropolitan edge and who work in downtown areas FHWA b.

In addition to roads and roadsides, the road system includes many engineering structures. These include concrete barriers, guardrails, noise barriers, bridges, culverts and pipes, and overpasses and underpasses.

Each of these structures has a particular ecological effect. Rigid safety barriers separating lanes on roads are common, especially in urban areas. The most common type of these structures is called a Jersey barrier. Some Jersey barriers are used for traffic separation on freeways and interstate highways, and many others are used only temporarily.

Temporary units are used mainly to enhance safety in construction work zones. The height of Jersey barriers averages around 32 in. Rigid safety barriers are also commonly used longitudinally on major nonlimited-access highways to safely separate the two directions of traffic and preclude left turns and U-turns. There is current concern with barriers being formidable obstacles to small- and large-animal movement across highways. Barriers can block animals when they attempt to cross the highway, making them vulnerable to traffic mortality.

Many different types of horizontal flexible and semirigid barriers, commonly known as guardrails, line the roadsides and medians of the roadway system. As with concrete barriers, guardrails are intended to constrain errant cars and trucks.

Guardrails normally provide space beneath and above the rail that allows movement of wildlife. The principal difference between rigid safety barriers and guardrails is the amount deflection that will occur when they are hit.

Right-of-way fences are used to keep people and animals from entering the berm, shoulders, and travel lanes of the highway. Many limited-access highways are lined with right-of-way fences, which enhance safety and reduce traffic mortality of large animals by reducing the crossing of animals.

The safest system is one with wide grassy medians and no hard barriers, where there is sufficient room for errant vehicles to recover before entering an opposing lane of traffic. No rigid barrier is needed if the median is approximately 50 ft or more in. Despite the safety offered by wide medians, there can be offsetting concerns because the median increases the width of the road right-of-way, including additional cost, availability of land in some locations, and compatibility of a wide right-of-way with nearby land uses.

Although wide medians in an additional loss of natural habitat, they may have less ecological impact than a narrow, paved median with a barrier or guardrail. Another advantage of a wide median is that the highway can be cost-effectively widened in the future with minimal disruption to traffic and to the adjacent properties, although if that happened, the ecological benefits of a wide median would be minimized or eliminated.

The decision to construct a new road over or under an existing facility is site-specific. Generally, minor roads should pass over major roads. This configuration takes advantage of off-ramp traffic being able to decelerate on the upgrade and the on-ramp traffic being able to accelerate on the downgrade Sharpe Although highways generally are constructed over waterways, the choice to span or pass under requires extensive analysis.

Sometimes tunnels are built instead of bridges, as was the case with the 2. A tunnel was constructed instead of a bridge because of concerns that a bridge would tower over a historic site, Fort McHenry.

Often it is desirable to depress the major road to reduce noise impacts and improve aesthetics. Span lengths, angle of skew, soil conditions, drainage, and the maintenance and protection of traffic on the existing route all must be considered.

Three-dimensional models of the alternatives are sometimes used to obtain informed public input into the decision. Noise barriers are designed and built primarily to muffle highway traffic noise in residential areas, schools, playgrounds, and other sensitive. Noise barriers may also be retrofitted on highways to enhance the surrounding community.

Almost all sound walls in the United States have been constructed since , and about two-thirds have been constructed of precast concrete and block. The other one-third of barriers are constructed of various materials, including wood, earth berm, and metal. The average noise barrier height is 10 to 16 ft, although some are over 23 ft. Ongoing construction efforts to address deficient bridges offer a singular opportunity to address and mitigate important ecological issues.

These issues are discussed in Chapter 3 ; mitigation of adverse effects of bridges and culverts is discussed in Chapter 4. The condition of bridges and other engineering structures is discussed later in this chapter. Understanding the ownership and maintenance responsibilities for roadways is important for planning and managing the coordination of environmental and planning issues discussed in later chapters of this report. On the other hand, McAdam's system was based on the principle that a well-drained road made of suitable material does not need the stone foundation of Telford's system, but could be built directly on the subsoil.

First McAdam placed a closely compacted to inch layer of stone which had been broken to an inch in diameter, and which was raised in the center to facilitate drainage. This was followed by a carpet of finer grained stone that was cemented by the setting of the powder, a process that was completed in stages, allowing the road's traffic to compact each stage.

The greatest advantages to McAdam's system were its speed and low cost, and it was generally adopted throughout Europe. However, it was the lack of a firm foundation for the roadbed that was to prove the ultimate undoing of macadam roads with the advent of heavy motor vehicles, especially trucks.

For that reason, on roads that had to support heavy loads, Telford's system of construction became the standard. During this same time period, the growth of turnpikes was resulting in much improved road conditions across England. Private individuals built roads themselves and then charged for their use, usually blocking passage by setting a long pole pike across the road.

Once the toll had been paid, the pole would be swung turned out of the way, allowing the travelers access to the road turnpike. By , 3, different turnpike companies operated 20, miles of highway throughout England. However, during the latter half of the 19th century, canal building and the growth of railroads outstripped the turnpikes, and roads in general became less important until the turn of the century.

As European settlers migrated across the Atlantic to the U. In America there were only Indian trails, and while they were long and quite extensive, they were also very narrow, allowing only for single file passage of foot traffic. Like their Inca counterparts, the natives of North America did not invent a wheel, and so did not develop roads that would accommodate wheeled vehicles.

Initially, America's early roads were no more than widened Indian trails which had been leveled and filled, most of them full of tree stumps that tripped horses and halted wagons. The expression, "I'm stumped," derived from this era, when vehicles were frequently hung up on tree stumps and could go no further until they'd been freed. Also, since most of these early roads ran through forests, the route was often marked by notches chopped on trees, from which evolved names like "Three Notch Road.

Not surprisingly, the overall development of transportation in the U. As in England, this was due both to increased canal building and the growth of railroads. But the advent of the motorcar changed all that for everyone, and the advent of the motor truck changed it even more. Obviously, motorized vehicles made it possible for both people and goods to travel both more quickly and more comfortably-so long as there were adequate roads upon which they could travel.

Thus the Good Roads Movement was born. Before proceeding with motor vehicles, we have to give some credit to bicycles for bringing attention to the need for good roads, since these two-wheeled vehicles enjoyed enormous popularity in the late 19th century.

Many clubs and cycling societies sprang up, including the League of American Wheelmen, a national organization founded in whose members began crying out for better roads. The first definite success of the fledgling Good Roads Movement was achieved in , when New Jersey became the first state to take responsibility at the state level for improving roads and formed a State Highway Department.

Massachusetts followed this example in , and by all the states had adopted similar programs. However, aside from outspoken cyclists and their leisure time needs, farmers were actually the earliest commercial agitators for the Good Roads Movement, since they needed a way to get their farm products to market. In addition, the railroads initially supported early efforts to improve local roads for farmers because it increased their own traffic. In , the Department of Agriculture opened an Office of Road Inquiry to assist in the development of better roads, and an often-heard slogan was, "Get the farmer out of the mud!

Senator John H. As Chairman of the Senate Committee on Post Offices and Post Roads, he introduced bills that appropriated money for the construction of post roads. Then in Sen. Bankhead got the Federal Highway Act passed, which has been the basis for a continuing federal aid road building program ever since.

The bottom section of the road was usually made of leveled earth and mortar or sand topped with small stones. This was followed by foundation layers of crushed rocks or gravel cemented with lime mortar.

Finally, the surface layer was constructed using neatly arranged blocks made from gravel, pebbles, iron ore or hardened volcanic lava. Much like the road signs on modern interstates and freeways, these stone pillars gave the distance to the nearest town in Roman miles and instructed the traveler on the best places to stop.

They also provided information on when the road was built, who constructed it and who last repaired it. Along with road signs and mile markers, Roman roads were also lined with state-run hotels and way stations. These simple posthouses consisted of stables where government travelers could trade their winded horse or donkey for a fresh mount. Switching horses was especially important for imperial couriers, who were tasked with carrying communications and tax revenues around the Empire at breakneck speed.

By stopping off at multiple posthouses, couriers could move as far as 60 miles in a single day. A view of a paved intersection of the ancient Roman roads in Leptis Magna, Libya, the largest city of the ancient region of Tripolitania, pictured in May They also doubled as toll collectors. Like modern highways, Roman roads were not always free of charge, and troops were often waiting to levy fees or taxes on goods whenever the route reached a bridge, mountain pass or provincial border.

Named for its medieval owner, Konrad Peutinger, the Peutinger Table is a 13th century copy of an actual Roman map created sometime around the 4th century A.