Safety effects of unsignalized superstreets in North Carolina

The safety study involved traffic flow adjustment, comparison-group, and Empirical Bayes analyses of 13 unsignalized superstreet intersections in North Carolina. The superstreets have been installed in the last few years across the state as opportunities presented themselves, but not necessarily at the most hazardous sites. The unsignalized superstreet countermeasure showed a significant reduction in total, angle and right turn, and left turn collisions in all analyses. Analyses also showed a significant reduction in fatal and injury collisions. The authors recommend that future analysts use a crash modification factor of 46 percent when considering the conversion of a typical unsignalized arterial intersection into a superstreet.