Smart Work Zone Deployment Initiative

About the research

Transportation agencies strive to mitigate the safety and mobility impacts of work zones using a variety of strategies as part of work zone transportation management plans. Closing one side of a divided multilane highway and crossing over traffic to the other side as a two-way operation is being used more frequently by transportation agencies. Work zones need to be designed within a given paved width, especially with counter-directional flow when traffic is crossed over to opposing lanes. The challenge faced by designers is in understanding the safety and mobility implications of the allocation of lanes and shy distances to barriers for a given paved width. For example, if a paved width of 26 ft were available, would it be better to have two 12-ft lanes with 1-ft shy distances or two 11-ft lanes with 2-ft shy distances?

The recently completed SWZDI project: Mobility and Safety Impacts of Work Zone Lane and Shoulder Widths attempted to address this question. While the project demonstrated that mobility and safety impacts of lane/shoulder widths in work zones can be modeled, it also had some limitations. The primary limitation was that safety analysis only considered right-side departures of vehicles in the right lane. Furthermore, the impact on vehicles straddling lanes was not quantified and all the locations with 1-ft shy distances were very short sections. Hence, there is a need to build upon the previous research to address these limitations and provide a more complete understanding of the safety and mobility impacts of lane and shoulder widths.

The current research will achieve the following objectives:

• Collect data from work zones with different lane widths and shy distances.
• Quantify mobility and safety impacts of the different combinations. Mobility performance measures (PMs) will include speed, speed-flow curves, and impact of enforcement or speed feedback signs. Safety PMs will include probabilities of edge line encroachment/barrier contact, and lane straddling. Impact of presence of adjacent vehicles on lane position and speed will also be evaluated.