PART 1
SIGNING
Professor of Civil Engineering Auburn University Auburn, Alabama
Part 1 of this chapter presents a comprehensive review of the design, construction, and maintenance of highway signs. Both single — and multiple-mounted sign supports are addressed, with an emphasis on highway safety. Breakaway supports with various types of slip bases, frangible bases, and post hinging systems are explained and illustrated. Commercially available devices and alternatives are identified and discussed. Guidelines on use and construction are summarized. An extensive list of references, which are noted in the text, concludes the section. Much of this material was derived from studies made by the author under a Federal Highway Administration project, NHI 38034, “Design, Construction and Maintenance of Highway Safety Features and Appurtenances.”
The capability of roadways to safely and efficiently serve vehicular traffic is dependent to a large extent on the adequacy of traffic control devices. The majority of motorists drive in an orderly and safe manner, provided they are given reliable regulatory, warning, and guide information. Motorists, through training and experience, develop expectations on when and in what manner they will be provided necessary information for safely controlling their vehicles. Motorists expect that similar traffic control devices will always have the same meaning and will require the same motorist action regardless of where they are encountered. This expectation has been enhanced by the use of uniform traffic control devices which enable motorists to consistently interpret the general intent of a device by its message, shape, and color.
The advantages of traffic control device uniformity were recognized long ago. The American Association of State Highway Officials published specifications of road markers and signs for rural roadways in 1925. A manual for urban roadways was published in 1929 by the National Conference on Street and Highway Safety. The unification of the standards applicable to the different classes of roadways was addressed by a joint committee of the American Association of State Highway Officials and the National Conference on Street and Highway Safety. The joint committee developed, and printed in 1935, the first Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD) [1]. That joint committee, although subsequently reorganized and named the National Committee on Uniform Traffic Control Devices (NCUTCD), has been in continuous existence and contributes to periodic revisions of MUTCD.
The benefits of traffic control device uniformity include increasing safety by providing the road user with required information for vehicle guidance or control at the right time and place and in the proper manner. Signs should be installed only where warranted. This can include locations where special regulations apply at specific places or specific times or where hazards are not self-evident. They also provide information of highway routes, directions, destinations, and points of interest. The general standards for signs provided in Chap. 2A of the MUTCD and those sections pertaining to the particular type of sign being installed should be followed to ensure proper placement and message uniformity [2].
