highways and guardrails in front of essential roadside objects and as central barriers in narrow medians. Main highways of new design now are being developed in this manner and corrections made to the extent practical on existing highways. The cost effectiveness of some of these features remains moot on low and intermediate volume highways and further studies are continuing for their more widespread application.
Traffic Control Devices
Traffic control devices are the several elements provided on highways to advise, guide, warn, regulate or otherwise inform the vehicle drivers. The basic types of devices are signs, pavement markings, roadside delineators and traffic signals. The 1971 Manual on Uniform Traffic Control Devices was approved by the Federal Highway Administrator as the national standard for all highways open to public travel. This Manual presents essential standards for design, location, installation and operation of all forms of traffic control devices and is the culmination of over 50 years of progressive development of the devices and national standards for their detailed and uniform use.
The history of these developments can be briefly reviewed in two stages. First are the series of individual and scattered instances to conceive and use some form of device. Second are the organized efforts to develop and attain acceptance of standards for national uniformity.
Early Traffic Controls
In 1745 stone markers were placed between Trenton and Perth Amboy on the principal highway between New York and Philadelphia. They were installed at 2-mile intervals and at intersections with other public roads. A public subscription was made to pay for them. In 1763 the Boston Post Road similarly was marked with mileposts.
The Pennsylvania State authorizing act in 1792 for the Philadelphia to Lancaster turnpike included requirements for mileposts and directional signs.
By 1902 some cautious automobile touring had begun, and the adventurers were losing their way. Often there were no signs at all, or where there had been signs, many had toppled over and been broken or faded beyond readability. As early as 1905, extensive signpost work was performed by the Buffalo Automobile Club in New York State, In the next few years, auto clubs across the country undertook the task of a basic directional signing on the principal highways within their areas. Despite their local efforts, there were no national or long route installations.
In 1913 the Lincoln Memorial Highway Association was organized and funds collected toward promotion and construction of a central east–west highway across the country. While the construction phase largely became promotional assistance to the State highway agencies, the Association shortly put into effect an entire route marking along existing roads. Painted red, white and blue band markings and symbols were placed on utility poles, clearly designating the chosen route. This example generated widespread activity by many motorist and local clubs to similarly, but distinctively, mark a selected and named route and foster its improvement. By the 1920’s, there were some 250 name routes, each with characteristic color bands marked on roadside poles. In some cases, several such routes overlapped, resulting in totem poles of multicolors. These color bands and symbols were gradually replaced by route numbers as the States installed signs designating them.
The Automobile Club of Maryland posting directional and mileage signs.
The widespread use of stone mileposts did not begin until the early 1920’s when mileposts appeared on the roads of a few States in the form of concrete marker posts. Gradually the mileposts began to be replaced by signs indicating mileages to places ahead to aid travelers. The rapid expansion and drastic changes in our Nation’s highway system beginning about 1910 were reflected in significant modifications in highway markings. The realinement and abandonment of roads, together with construction of new highways, made many of the old mileage signs virtually useless, and they were gradually replaced by signs displaying point-to-point distances and route numbers based
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