Speed Variation and Safety in Work Zones

The overall goal of this research is to develop additional knowledge and practices that can be used to improve driver and worker safety in work zones and, as a result, mobility through work zones. The research will focus on high speed roadways (e.g., highways and freeways) and typical mobile construction and maintenance operations that occur on such roadways (e.g., paving and re-striping). To meet this goal, the proposed research focuses on variation in vehicle speed from the average speed in work zones. The research aims to confirm the need to address vehicle speed variation, identify means to minimize speed variation, and recommend ways in which Oregon Department of Transportation (ODOT) can minimize and mitigate the effects of speed variation. Specifically, the objectives of the research are to: (1) Document the prevalence and magnitude of variation in vehicle speed from the average speed in work zones, and how this variation compares to variation in free flow conditions without a work zone present; (2) Determine work zone conditions and traffic control measures that can lead to greater variation in vehicle speed from the average speed; (3) Identify techniques within the traffic control plan and conduct of work operations for minimizing and mitigating variation in vehicle speed from the average speed in work zones; (4) Develop recommendations for both minimizing speed variation and mitigating the effects of speed variation in order to improve safety and mobility in work zones; and (5) Recommend a data collection plan for ODOT to study/monitor the speed variation in work zones and the corresponding impacts. When developing recommended traffic control measures, special consideration will be given to the potential use of new technologies such as smart work zone technologies that monitor the presence of slow-moving vehicles and queuing, and communicate these conditions to oncoming traffic. The potential integration of existing variable message signs (VMSs) and display messaging options will also be considered in order to take advantage of existing roadway infrastructure. Additionally, the staging and implementation of construction/maintenance work operations and equipment will be evaluated as possible means to minimize speed variation. The research plan for meeting the study objectives is illustrated in Figure 1. The overall plan contains two overarching phases: Phase I to document and characterize speed variation in work zones and identify impacting factors, and Phase II to identify, develop, and communicate techniques that can be implemented by ODOT to minimize and mitigate speed variation to improve safety. Phase I is designed to address Objectives 1 and 2, and Phase II will focus on Objectives 3, 4, and 5. For each phase, Figure 1 also shows the data needed to meet each objective, along with the research activities (data collection and analysis efforts) to be conducted to fulfill the objectives. The specific tasks in each phase are described in more detail below. As shown in the study timeline, Phase I will be conducted prior to Phase II. The results of Phase I will, in part, inform the data to be collected and steps to be taken in Phase II. Phase II will not start until the TAC meets to review the results of Phase I, and authorization to start Phase II is provided by ODOT.