Examensarbete

This thesis overview the gap acceptance behaviour in a saturated two-lane roundabout and the implementation of local measured critical gap times into microscopic simulation. The purpose is to measure the critical gaps in a saturated two-lane roundabout to investigate how gap acceptance differs between entering vehicles depending on desired direction and position of circulating vehicles. An additional purpose is to implement the measured critical gap times into the traffic simulation software VISSIM and compare the simulated results with results given by VISSIM default values. The thesis includes a literature study on subjects related to micro simulation and gap acceptance of two-lane roundabouts. The used data was collected in a field study of the saturated two-lane roundabout Spillepengen in Malmoe, Sweden. VISSIM was used to build and run two microscopic simulation models to test different values of critical gaps. Conclusion is that there is a significant difference in gap acceptance depending on desired direction and position of circulating vehicles. Another conclusion is that the default values for minimum gap in VISSIM generate the same result as the implemented measured values from the field study. The results also show that the headway distribution of the circulating flow is of great importance to simulate a correct entry capacity.