Determining a suitable position for U-turns near signal-controlled road junctions

Abstract

Previous research has shown that vehicles making U-turns at a signal-controlled urban road junction can negatively affect the performance of the junction. This paper reports on a study carried out to determine a suitable position to allow U-turns at signalised intersections in Tehran, Iran, based on their effects on network travel time. A section of the traffic network of Tehran was modelled using specialist software. To make the results more realistic, local traffic and driver behavioural parameters were calibrated and fed into the software. Various scenarios with different intervals were developed, with ten median openings before a signal-controlled junction and ten median openings after the junction. The results indicate that if the median opening for conducting U-turns is located 190 m before the junction, the network delay is lower than the other scenarios considered.