Evaluating the Safety Risk of Active Night Work ZonesAuthor/Presenter: Ullman, Gerald L; Ullman, Brooke R; Finley, Melisa D
In this report, researchers present an assessment framework for evaluating the expected crash consequences of performing a particular work activity on a given highway at night versus doing that same activity during the day. Researchers predicate the framework on the availability of normal crash rates (crashes per 100 million-vehicle-miles), differentiated by daytime and nighttime conditions, on the particular roadway segment of interest. These normal rates are then adjusted on a percentage basis to account for the incremental increase in crashes expected under both the daytime and nighttime work conditions. An analyst would multiply the adjusted crash rates, representing the additional crash risk due to work activities, by traffic volumes expected to encounter the work zone in either the daytime or the nighttime period and the length of the work zone to determine the number of additional crashes that would be expected to occur due to the work zone in either period. Also included in this report is a review of several potential countermeasures identified by the research team to reduce crashes resulting from active night work zone. Researchers provide a critique of each one with regard to potential adoption consideration by the Texas Department of Transportation. Overall, researchers could not justify widespread or blanket adoption of any of the countermeasures.