The planning and design of work zones is one of the greatest challenges faced by highway agencies, given the potential operational and safety effects of work zones and the constraints that work zones place on project duration and phasing. The AASHTO Highway Safety Manual (HSM) has crash prediction methods for many roadway segment, intersection, and ramp facilities, but none of the available methods address the safety performance of these facilities with work zones in place. As a result, highway agencies rely on judgement and past experience, rather than quantitative safety analysis, in developing geometric designs and traffic control plans for work zones.

There is a clear need to better understand the quantitative safety performance, including crash frequency and crash severity measures for specific work zone features (lane closures, lane shifts, shoulder closures, median crossovers, and detour roadways), geometric design features in work zones (lane width, shoulder width, horizontal curvature) and offsets from the traveled way to traffic barriers and traffic control devices. New knowledge on these topics should be assembled into a quantitative crash prediction methodology that can be used by highway agencies to develop the maintenance of traffic plans for work zones. The methods ultimately developed should be capable of comparing the expected safety performance of the work zone to the safety performance of existing roadway prior to the beginning of work and to assist in planning work zone configurations and project phasing to limit any increase in crashes during the work period.

The objective of this research is the development of crash prediction methods for work zones suitable to guide highway agencies in planning and design of geometrics and traffic control for long-term work zones.