Evaluation of Work Zone Split Traffic Symbol Sign

Effective signage that is easy to understand facilitates safe driving through a work zone. While the guidance for work zone signage in the Manual on Uniform Traffic Control Devices (MUTCD) is suitable for many conditions, there may be instances where alternative signage may be more effective at enhancing safety. This project evaluated the use of alternative signage for closure of a middle lane in a freeway work zone on a bridge rehabilitation project on I-170 in St. Louis, Missouri. The alternative signage displays the lane arrangement in a single sign while the MUTCD signage shows the movements to the left and the right sides of the work area on separate signs. The evaluation of the alternative signage included stakeholder and driver surveys, operational and safety analyses, and the collection and analysis of field videos to assess driver behavior. The analysis of field videos showed that drivers may have adapted to the alternative signs as the rate of lane changes decreased between the early and late periods of construction. Stakeholder interviews found that personnel from MoDOT and the contractor generally thought that the alternative sign communicated information more clearly but had mixed opinions on whether the use of the sign improved safety. Drivers did not express any concerns regarding the use of the alternative sign through a website that collects feedback on MoDOT work zones. A review of crash data found that crash patterns during the work zone period were similar to the crash patterns before the work zone was in place, and the use of the alternative sign did not appear to be a contributing factor in any work zone crashes. Analysis of RITIS traffic data found that the use of the alternative sign did not have an impact on travel times in the vicinity of the work zone. Overall, the evaluation found that the alternative sign communicates information clearly and does not cause any adverse impacts to work zone safety and operations.