Abstract
The use of 12-inch nominal diameter traffic signal lenses has increased significantly during the last several years. In consideration of the wide acceptance of these larger lenses, it was deemed desirable to establish criteria as a guide for their use. Adherence to the criteria set forth in this report will serve to limit usage of the 12-inch lens, minimize their misuse and, thereby, prevent possible loss of their effectiveness through overuse. The criteria presented herein recognize the differing needs of the three basic types of districts where signals are used- rural, urban and central business. (For purposes of this report, urban district" is considered to include all sections of an urban area other than the central business district).