This paper analyzes the comprehensibility of current and experimental signs to indicate a photo enforced traffic signal ahead. In the City of Arnold, Missouri, four signalized intersections are photo enforced and have been indicated with the current text only photo enforced regulatory sign posted below the traditional signal ahead warning sign. These signs were replaced with an experimental sign, which indicates a photo enforced traffic signal ahead with one regulatory sign. The evaluation is performed usingthree surveys, one for the currently approved signage, and two for the experimental sign, one shortly after installation and another about 9 monthsafter installation. The study found that older drivers (age 65+) have greater difficulty in comprehending both the current and experimental photo enforced signage compared to younger drivers. However, older drivers comprehension of the experimental sign improved more over time than other drivers comprehension (62.5% to 75.8% correct comprehension for older vs. 79.8% to 81.2% for others). The results indicate the experimental sign has potential to improve safety by better delivering its intended meaning, particularly to older drivers, but also, that it may take older drivers more time than other drivers to learn about and comprehend new signs.
Abstract