I have an intersection I am trying to evaluate where dual eastbound left turn lanes exist. The receiving lane tapers down to a single lane at 540 feet north of the intersection. In SimTraffic simulation shows vehicles in the second eastbound left turn lane try to merge into the first lane prior to the signal on the eastbound approach. This improperly calculates the queue lengths along the eastbound left turn lane (over estimate by about 1000 feet). How do I get vehicles to utilize both left turn lanes and merge on the north leg of the intersection?

Lane drops such as this create points at which a mandatory lane change is needed. Read up on "Driver Parameters" and "Lane choice and Lane Changes" in the help topics. Use caution when adjusting driver parameters though. Also, under link settings in synchro 6, you can adjust the base values for Lane Change Distance.

Eric Royer
Caltrans