Date of Award
Master of Science
Civil, Construction, and Environmental Engineering
Civil Engineering (Transportation Engineering)
[Crashes at signalized intersections account for approximately 20% of all crashes both nationally and within the State of Minnesota. Several research efforts have suggested that the use of all-red clearance interval at signalized intersections may reduce intersection crashes, particularly those related to signal violations. However, other research has shown that an all-red interval does not result in a reduction in crash rate. This research also evaluated the reduction in crashes due to use of an all-red interval at intersections within the City of Minneapolis. A cross-section analysis using generalized linear mixed models with a Poisson error distribution and log link function and mixed linear models with transformed data were used to compare Minneapolis sites with and without the all-red clearance interval. Results of the analysis agree with the previous studies that indicate no effect. A before and after analysis was also conducted to evaluate both short-term reduction in crash rate lasting approximately one year after implementation of an all-red interval. The research also evaluated user costs in the form of increased delay due to reduction in capacity that would result from implementation of the all-red interval at the remaining Minneapolis intersections that currently do not use the interval. Although a short-term effect was noted, the temporary safety benefits may not outweigh the long-term reductions in capacity and should be considered before implementation. Additionally, although no statistically significant long-term benefit was demonstrated, research results do not provide guidance on elimination of the all-red clearance intervals at intersections where it is currently in use.]
Molly McCarthy O'Brien
O'Brien, Molly McCarthy, "Effectiveness of the all-red clearance interval on intersection crashes" (2003). Retrospective Theses and Dissertations. 19528.