Design of mini roundabouts with adaptive traffic lights to improve vehicular travel times and roundabout capacity in metropolitan cities

The high travel times in urban roundabouts are due to a greater current vehicular demand over the low capacity of the initial design. For example, today, a driver takes between 13 to 21 minutes longer on a 30-minute trip. Due to this, the need arises to modify and innovate in the geometric design and traffic lights of these intersections. Therefore, this article proposes the joint application of geometric redesigns based on mini roundabouts and adaptive traffic lights in urban roundabouts. This seeks to reduce travel times and increase vehicular capacity. To carry out this design, an application case of a traffic light roundabout with five branches located in Metropolitan Lima was selected, which presents high vehicular travel times. The roundabout data was obtained by surveying and processing the information in the field. With these data, the current situation of the roundabout is micro-simulated, calibrated and validated using Vissim 9. Subsequently, the design of scenario 1 of the geometry with mini-roundabouts and scenario 2 of geometry and adaptive traffic lights was carried out. The evaluation of the results of both scenarios with the current situation of the intersection showed that travel times were reduced between 9 and 81%. In addition, vehicular capacity at the roundabout increased by 31%, maintaining its service level F.