Page:Manual on Uniform Traffic Control Devices for Streets and Highways, 1961 Edition.pdf/24

 Part I

SIGNS

The oldest device for controlling, safeguarding, or expediting traffic is the traffic sign. As in the case of any other type of traffic control device, signs should be used only where necessary and where justified by facts and field studies. Signs are not ordinarily needed to confirm well-known or universally recognized rules of the road, such as that requiring drivers to keep to the right, but they are essential where special regulations apply at specific places or at specific times only, or where hazards are not self-evident. They are also needed to give information as to highway routes, directions, destinations, and points of interest.

This Manual prescribes standards for the signing of all classes of public highways. To the extent that advanced design has reduced physical hazards and traffic frictions, the need for warning and regulatory signs on modern highways has been eased. On the other hand, the increased volume and speed of traffic on elaborate expressways has made the requirements of directional signing progressively more exacting. The standards in this Manual are designed for the great bulk of the street and highway mileage that constitutes the basic road system. At the same time, however, the special needs of expressways are recognized and, where appropriate, special expressway sign standards are prescribed.

For the purposes of this Manual, "expressways" include all types of high-speed highways, usually characterized by three distinctive features-divided roadways, controlled access, and grade separations at intersections. Where any of these features are lacking, expressway signs may not be fully applicable, and standard signs and signals as otherwise provided for should be used, with such enlargement or other modification as is required to adapt them to expressway conditions.

It must be emphasized that highway signs, and particularly