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Traffic control device evaluation program : FY 2016.
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2017-03-01
[PDF-3.84 MB]
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Abstract:This report presents findings on three different activities conducted in the Traffic Control Device Evaluation Program during the 2016 fiscal year. The first two activities are evaluations of full-matrix color light-emitting diode changeable message signs with 20 mm pixels. The first evaluation compared legibility and detection of roadway hazard objects for signs with and without sponsor acknowledgement logos on 1/3 of the sign. A closed-course evaluation was conducted day and night on a closed course with 30 drivers traveling 30 mph. Three sign types were evaluated: green background travel time signs with white letters, black background text signs with white letters, and blue background text signs with white letters. Sponsor logos had little or no effect on sign legibility or object detection distances. When an effect was significant, it was observed only for specific types of signs or placement locations. The second activity was a nighttime evaluation of legibility of these same signs comparing three different fonts: 16 inch letters (20 x 12 pixels), 18 inch (23 x 15 pixels), and a more condensed 18 inch letter (23 x 14 pixels). The study demonstrated drivers can read messages with 18 in. letters farther away than 16 in. letters. But when expressed as legibility
index, all of the fonts tested hover around the minimum legibility index of 40 ft/in recommended in the TMUTCD. This suggests that there is room for improvement in the design of individual letters. The third activity provided an update to the worksheet used to determine signal preemption needs at railroad grade crossings. The updates provide default values in some frequently used fields, eliminated some fields rarely used, and minimized the decision making for those filling out the form.
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