A surrogate safety analysis to evaluate the impact of circulatory pavement markings in two-lane roundabouts
University of New Brunswick
This study involved a safety evaluation of multiple pavement markings schemes at the two-lane roundabout at the intersection of Smythe Street and Route 8 in Fredericton, New Brunswick using both automated and manual surrogate safety analyses. Several competing theories exist regarding which is the best practices for the use of circulatory lane pavement markings in two-lane roundabouts with two-lane entrances and exits. Some suggest that having no pavement markings fosters a safer environment for drivers, while others promote the use of circulatory pavement markings of various patterns as preferred options. The pavement marking schemes studied in this project were: no circulatory pavement markings installed (baseline case), circulatory pavement markings installed in accordance with the TAC MUTCD-C guidelines (Scenario 1), and an alternative circulatory lane pavement marking scheme with bolder lines (Scenario 2). In Scenario 1 and Scenario 2, traffic conflicts were observed at lower rates than in the base cases, however, the severity of the observed traffic conflicts remained approximately the same. Off-tracking events, in which vehicles failed to maintain their lane position while circulating the roundabout, were found to be reduced by 24.3% in Scenario 1, and 19.2% in Scenario 2. These findings support that circulatory lane pavement markings in two-lane roundabouts contributed to an environment with improved safety performance compared to the facility with no circulatory markings installed. Further research is required to confidently discern whether Scenario 1 or Scenario 2 provides the best safety performance.