Results of Micro-Simulation Model for Exploring Drivers’ Behavior on Acceleration Lanes

This study examines drivers’ behavior on acceleration lanes, close to the convergence between the main and the secondary traffic streams, by means of traffic micro-simulations. Experimental data collected videotaping two acceleration lanes in Italy have been used to initially calibrate a simulation model and to validate it subsequently. The analyses had focused on both vehicles coming from the on-ramp, in terms of entrance points dispersion into the main traffic stream along the acceleration lanes, merging speeds, and acceleration rates reached, and on vehicles driving on the freeway right lane, in terms of vehicles categories, traffic volumes, and speeds. The maneuvers have been implemented in the TransModeler traffic simulation package and several scenarios have been considered, changing the traffic composition and the speeds at which drivers enter the acceleration lane from time to time. This led to obtain a large number of case studies, where the mutual influence between the two flows combined with the vehicle performances and the psychophysical characteristics of drivers, have led to an initial evaluation of the main variables in respect of which the required length for the specialized lanes depends. Road design guidelines’ standards have been later compared to what was observed in reality and it can be claimed that the microscopic traffic model in some cases confirms the standards of road design guidelines while, in other cases, contradicts them.