Research on the Impact of Traffic Volume on U-turn at Intersection

Direct left turn (DLT) movements have a lot of safety and operation problems. They increase conflicts, delay and reduce capacity of the roadway. Increasingly, many states and transportation agencies are considering using right-turns followed by u-turns or u-turns followed by right-turns (RT+UT or UT+RT) as an alternative to DLT. However, the impact of the treatment and applicability is still not very clear in China for the different traffic conditions with overseas countries. The objectives of the study were to examine the influence of volume on arterials and percentage left turns to the effectiveness of U-turns at signalized intersections and to set up a set of guidelines for using this alternative in China. To implement the objectives, study of the current applications and a simulation analysis with PTV VISSIM and COM module for developing guidelines based on volume and delay. For the precision of simulations, the simulation parameters were calibrated by using the field data. The trend lines of the relationship between average delay and different traffic volume on arterials and percentage left turns was developed. The findings are helpful in the selection of access managements and various driveway left-turn alternatives on multilane roadways.