Comparison of Driver Navigation at Turbo Roundabouts and Modern Two-Lane Roundabouts: Simulation Study

Roundabouts can be a solution to safety concerns common to conventional intersections. Recently in the United States, there has been an increase in the conversion of problematic intersections to roundabouts to improve their safety. However, there are some important considerations and challenges to make roundabouts safe for all users, especially multilane roundabouts. There may also be challenges for drivers to navigate a newly built or a new type of roundabout. Roundabout features such as pavement markings and signage play an important role in driver navigational performance. This research was an effort to evaluate new roundabout design and existing roundabout safety and operational features such as signs and pavement markings. The focus was on how such features influenced the performance of drivers, specifically at multilane roundabouts. Two-lane roundabouts and rotor turbo roundabouts were evaluated. A driving simulator was employed to test various simulation scenarios in a virtual world. The results indicate that lane keeping and higher navigation speeds are still problems at multilane roundabouts. The rotor turbo roundabout outperforms the two-lane roundabout in enabling correct lane choice and navigation speed control by drivers. Furthermore, it was found that roundabout signs and pavement markings used in the United States can be adopted for turbo roundabouts.