Evaluation of Alternative Intersections and Interchanges

There is a recent trend of building roundabouts on highspeed roads, often with the considerable presence of heavy vehicles. With the increased presence of trucks on roundabouts, the issue of overturning has become a concern. Although some geometric, vehicle, and loading factors have been connected to rollover, the safety performance of roundabouts built on high-speed roads is not well understood. This study compared the heavy vehicle rollover risk for roundabouts on lowand high-speed roads, while also examining roundabout circulatory superelevation, aggressive driver behavior, roundabout readability, and nighttime conditions in the context of rollover. Moreover, the critical and follow-up headways were estimated for trucks and other vehicles at roundabouts located on the lowand high-speed roads and during daytime and nighttime conditions.