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Project Details

Title:Impact of Regulatory Hybrid Changeable Message Sign on Traffic Safety under Different Freeway Geometric Designs
Principal Investigators:Xianfeng Yang
University:University of Utah
Grant #:69A3551747108 (FAST Act)
Project #:MPC-610
RH Display ID:13698
Keywords:crash rates, crash severity, freeways, geometric design, highway design, light emitting diodes, traffic safety, variable message signs, variable speed limits, visibility, white, yellow


The Utah Department of Transportation (UDOT) has implemented a Variable Speed Limit (VSL) zone on a section of I-80 using regulatory hybrid Changeable Message Signs (CMSs). In the current systems, the CMSs have been operated with white LED numbers on the black background. However, it has been found that the visibility of those numbers that indicate speed limits has become a problem during both winter and summer seasons. Hence, UDOT is now in the process of installing a new CMS system which replaces the color of white CMS LED by yellow. In the literature, although many recent studies have studied the impacts of CMS's visibility on improving safety, limited efforts have studied such impacts under different freeway geometric designs. By collecting historical crash locations in the VSL zones, our research team will further discuss how the new CMS can help to prevent crashes in various geometric design scenarios. By comparing the visibility of yellow-legend and white-legend CMS systems, the results will be discussed for the legend color selection for CMS. The collected safety data will be used to analyze the impacts of CMS on potential crash rate and severity using surrogate safety evaluation method.

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NDSU Dept 2880P.O. Box 6050Fargo, ND 58108-6050