Estimation of left-turn capacity at the unsignalized intersection

The capacity of unsignalized intersections is a significant value that indicates traffic conditions as well as network performance at urban and rural roads. These intersections are the most numerous on the road network. Inaccurate determination of unsignalized intersections capacity can give a misconception of the traffic conditions on the network. Researches about unsignalized intersections are mostly based on HCM and Harders' / Siegloch formula for capacity calculation. Measuring capacity values in real traffic flow under continuous queue conditions showed a significant deviation from the theoretical capacity values. The simulation of traffic flows in two different traffic capacity software also showed the difference in the simulated environment from theoretical capacity. Software based on HCM (Synchro) showed the same values as HCM in theoretical capacity, but different values in dynamic simulation (Simtraffic module). AnyLogic software based on the different model showed lower capacity values (very close to measured on field values) than the theoretical model. Findings from this study can be used for improvement of capacity analysis model as well as software for this purpose.