Evaluation of the influence of vehicular U-turns on the number of vehicle conflicts at a T-type intersection without signal lights, with and without a U-shaped Lane, with signal lights, with and without a U-shaped Lane using Vissim 9.0 and SSAM

In Lima, U-turns, although prohibited at many urban intersections, are carried out persistently, generating congestion and increasing the number of road conflicts. This study evaluates the influence of these maneuvers on a T-type intersection under four configurations: T-type intersection without traffic lights, without and with an exclusive U-lane, with traffic lights, without and with exclusive U-lane. The research was carried out at the intersection of Av. José Antonio Lavalle with Alameda San Marcos, an area with a high influx of vehicles and pedestrians. Using simulations in VISSIM 9.0 and conflict analysis in SSAM, vehicular conflicts were quantified and evaluated using safety metrics such as Time to Collision (TTC). The results show that the intersection without a traffic light and without an exclusive U-lane has 145 conflicts, the intersection with an exclusive U-lane and without a traffic light reduces that figure to 93, the traffic light configuration without an exclusive U-lane reduces conflicts to 117, and the configuration with a traffic light and exclusive lane for U-turns further reduces conflicts to 79. These figures represent reductions of 35.9%, 19.3 and 45.5%, respectively, compared to the configuration without an exclusive U-lane and without traffic lights -initial situation-. Likewise, severe conflicts with TTC=0 maintain a proportion according to the total conflicts of the intersection for each configuration. The study concludes that the proper management of U-turns, combining traffic light control and exclusive U-lanes can significantly reduce vehicular conflicts.