This report represents efforts to design and evaluate a new sign design for emergency route trailblazing in a two-part series. Study was an off-road field experiment conducted to determine the best sign color combination, letter stroke width, and letter size for the emergency sign. Based upon the results of that first study, three color combinations were chosen for testing (black on coral, black on light blue, and yellow on purple) against a baseline color combination of black on orange. The test signs to be further tested featured D series, 125-mm (5 in) height letters. Study 2 was conducted using an instrumented vehicle and survey questionnaire through a construction zone-related detour. The independent variables of interest were sign color combination, age, and visibility condition. The findings of Study 2 indicated that use of a color combination other than the traditional orange background with a black legend will improve driver performance and safety when used for trailblazing during critical incidents. Based on the conclusions and other anecdotal evidence, the following recommendations were made: 1. Do not use a black on orange sign for trailblazing around a critical incident if an existing detour/construction zone is in place. 2. Do not use a black on coral sign for trailblazing around a critical incident. 3. A black on light blue sign is recommended due to its generally favorable subjective ratings and for minimization of the number of turn errors made by drivers in an overlapping detour. 4. Despite recommendation 3, it is important to note that the black on light blue sign fades to take on the appearance of a regulatory sign when headlights reflect onto it. 5. If the black on light blue sign is deemed inappropriate due to its appearance as a regulatory sign at night, consider using the yellow on purple color combination. In this study, the yellow on purple sign color combination resulted in fewer turn errors than black on orange and it was generally rated favorably by drivers, especially younger drivers.

This report represents a Phase III effort to design and evaluate a new sign design for incident route trailblazing. The colors evaluated were fluorescent coral, fluorescent purple, fluorescent yellow-green, and non-fluorescent purple. The results indicate no significant differences in driving performance with regard to the four experimental sign color combinations. Regarding the subjective preference questionnaires, significant questionnaire results along with trend information suggest that black on fluorescent yellow green was the most preferred by younger and older drivers during both day and night visibility conditions. Nonetheless, this sign color has been assigned by FHWA for pedestrian, school, and bicycle crossings, which eliminated the opportunity to use fluorescent yellow-green as a unique sign color for trailblazing in incident management situations. Preference for non-fluorescent yellow on purple consistently increased at night when the sign became more luminant; however, the overall preference for this sign color combination was lower than for the other sign color combinations tested in this study. With the elimination of these two signs, the remaining contenders for a unique sign color combination were black on fluorescent coral and fluorescent yellow on fluorescent purple. Black on fluorescent coral was ranked significantly higher than fluorescent yellow on fluorescent purple for visibility and for overall preference. Questionnaire trend information suggests that black on fluorescent coral was more preferred than fluorescent yellow on fluorescent purple during daytime viewing conditions and less preferred than fluorescent yellow on fluorescent purple during nighttime viewing conditions. The overlay film used for the fluorescent coral sign was a first generation material that can reasonably be expected to result in improved nighttime luminance when produced in a full production run. In addition to the study results, drivers commented that the arrow on the sign was too small to determine directional information from a comfortable distance. Based on such driver comments, the research conclusions, and the federal regulations enacted since the outset of this series of experiments, the following recommendations are made: (1) black on fluorescent coral should be used as a unique incident management sign color, and (2) the directional arrow on the sign should be larger.

This project entailed the design, development, testing, and evaluation of intersection decision support (IDS) systems to address straight crossing path (SCP) intersection crashes. This type of intersection crash is responsible for more than 100,000 crashes and thousands of fatalities each year. In developing these IDS systems for both signalized and stop-controlled intersections, a top-down systems approach was used that determined the necessary system functions and evaluated the capability of different technologies to perform those functions. Human factors tests were also conducted that evaluated the effectiveness of warning algorithms and infrastructure-based driver-infrastructure interfaces in eliciting a stopping response from drivers about to be involved in an SCP intersection crash. Results indicated that further technological development is needed for the sensing and intersection state IDS functions. Furthermore, infrastructure-based warning interfaces tested were greatly outperformed by previously-tested in-vehicle warnings. Thus, future research on IDS systems should focus on their infrastructure-cooperative configuration, where the system supports an in-vehicle warning.