The Study of Methodologies for Estimation of Lane-Changing Rates; A Case Study: A ramp-Weaving Segment in Isfahan

Weaving segments exist where two significant traffic streams cross each other’s path at grade over a length of highway. The weaving maneuvers intending to perform lane changes in these segments cause a level of turbulence in the traffic flow. The turbulence leads to extensive speed changes, the reduction of the level of service and the safety in these segments. Therefore, this study, which has used the actual lane-changing rate, attempts to evaluate the performance of the model that was proposed in the fifth edition of Highway Capacity Manual (HCM 2010) and its calibrated model based on Tehran highways. Thereby, the field-data was collected on the ramp-weaving segment of a freeway in Isfahan, using a closed circuit observation technique. The procedure was of 7 fifteen-minute time steps of recording at different hours of a working day. The findings in this study show the weakness of the HCM 2010 in the lane-changing rate estimation (especially non-weaving flow) in the way that it under-predicts the rates in all cases and the calibrated model could only adjust it in prediction of non-weaving lane-changing rate. Even the calibrated model has negatively affected the HCM 2010 in estimation of weaving lane-changing rate.