IGuidelines forTraffic SignSymbols

O the last several decades, the use of symbol signs on North American highways has increased significantly. Research has shown that older drivers have difficulty in detecting, reading and understanding symbolic traffic signs. Previous research on their comprehension indicates that some symbols are clearly understood by 90 percent or more of the drivers, while others are understood by fewer than half. Swanson Transportation Consultants was awarded a 36-month contract from the U.S. Federal Highway Administration to undertake a systematic research program on the traffic sign symbols in the 1988 U.S. Manual on Uniform Traffic Control Devices (MUTCD)l. The program’s objectives were to: ■ determine the effectiveness of symbol signs including identification of those that are problematic for the general driving population and for older drivers in particular ■ develop and test alternative symbol signs; ■ investigate the individual elements of symbol signs to determine which elements are critical to effective sign design; ■ develop symbol sign design guidelines. Focusing on design guidelines for traffic sign symbols, this paper summarizes the overall research program, the results of the key tests and the symbol redesign process. Phase 1 Testing