USE OF EMPIRICAL BAYESIAN METHODS TO ESTIMATE TEMPORAL-BASED CRASH MODIFICATION FACTORS FOR CONSTRUCTION ZONES

摘要

Many studies have been conducted to estimate the traffic safety impacts of roadway construction.Overall, the results of the analyses have varied widely, traditionally attributed to site-to-site andproject-to-project differences. In this paper, researchers describe an effort to use empiricalBayesian (EB) techniques to develop temporal-based construction zone crash modificationfactors (CMFs). Specifically, separate CMFs were estimated for various time-of-day (daytime,nighttime), work status (work activity occurring at the site, work area inactive), and temporarytraffic control (temporary lane closure present, no lane closure present) conditions.Daily project inspector diaries from 64 freeway construction projects in four states wereanalyzed to determine hours of work, hours and locations of temporary lane closures, and thenumber of travel lanes closed during each work period. Researchers used EB methods in abefore-during study design to investigate the safety impacts of the different work zone conditions.Work activities requiring the temporary closure of one or more travel lanes resulted in the largestCMFs (i.e., the largest increases in crashes), followed by periods of work activity that did notrequire a lane closure (i.e., work was occurring in the median or beyond the edge of the travellanes). The lowest increase in crashes occurred during periods when work was not occurring atthe project. Interestingly, the CMFs during work activity did not vary significantly betweendaytime and nighttime conditions when there was a lane closure. The results suggest that EBmethods can be useful in assessing temporal factors influencing road safety.