Balancing the Costs of Mobility Investments in Work Zones: Phase 1 Final Report

Author/Presenter: Savolainen, Peter T.; Gates, Timothy J.; Barrette, Timothy; Rista, Emira; Datta, Tapan K.; Ranft, Stephen E.
Abstract:

Work zone safety and mobility continue to be critical transportation concerns in Michigan and elsewhere. Previous research has led to the development of a variety of tools, performance measures and decision-making frameworks to analyze work zone safety and mobility. This Phase 1 research sought to provide additional guidance towards assessment of safety and mobility strategies for work zones. The Phase 1 project objectives were as follows: 1.) determine the accuracy of existing methods for estimating delay and diversion; 2.) determine the cost-effectiveness of select strategies that have been implemented; and 3.) provide guidance towards development of work zone decision support tools. The specific tasks included an assessment of the national state-of-the-art and state-of-the-practice, a survey of travelers to gain insight into public perceptions of work zone operations and delay, and collection and analysis of work zone operational, safety, and cost data. The results showed that the median acceptable work zone travel delay reported by Michigan travelers was 10 minutes. Using data collected from several Michigan freeways, work zone travel speeds were found to remain relatively stable up to a flow rate of approximately 1,700 vehicles per hour per lane. Beyond this point, speeds declined (and subsequent delays increased) dramatically. The work zone crash analysis found incremental crash increases when comparing single-lane closures to shoulder closures, double-lane closures to single-lane closures, and lane shifts to double-lane closures. When comparing Michigan safety results to Highway Safety Manual data from California and Missouri, it was found that the effects of work zone length and duration were very similar between Michigan and Missouri, although the California effects were slightly different. Assessment of the costs associated with nighttime versus daytime asphalt resurfacing projects on freeways found some differences in the actual paving costs per lane-mile, but no differences between other related costs. The report also provides guidance for development of a Phase 2 research plan.