Transit signal priority strategies applied in roundabouts to reduce conflicts and vehicular travel times

In the last 20 years, the use of roundabouts has become widespread worldwide. This is due to the advantages they offer over other types of intersections, such as their ability to achieve a continuous vehicular flow and provide greater road safety for drivers and pedestrians. However, when a roundabout is not working properly, its operational capacity is exceeded. In this scenario, increases in directional vehicular conflicts and in travel time are observed, which directly affects the users of the road system. These problems are mainly generated by lane changes and queuing vehicular flow that can block some roundabout accesses. In Peru, most of the roundabouts that present this type of problem have not been designed to meet the exponential growth of the vehicle fleet in recent years, leading to congestion and delays because ofinadequate road planning. For this reason, the existence of roundabouts that exceed their capacity is a latent reality that is not only present in Peru, but throughout Latin America. Given this problem, the application of transit signal priority strategies is proposed to reduce vehicular conflicts and travel times. For the present investigation, a traffic light roundabout located in a commercial area of the city of Lima was selected as a case study. It is characterized by having many heavy vehicles and being part of the route of a Bus Rapid Transit (BRT) transportation system. The effectiveness of the proposal was validated using Vissim software. The results obtained demonstrate the influence of traffic light priority strategies reducing conflicts by 15% and vehicular travel times by29%.