Safety Analysis of Access Zone Design for Managed Toll Lanes on Freeways

Abstract

On freeways, managed lanes (MLs) have emerged as an effective dynamic traffic management strategy. MLs have been successfully implemented as an important facility in improving traffic mobility and generating revenue for transportation agencies. In this study, scenarios were built and tested in microsimulation to specify the safest accessibility level and decide on the safe weaving length near access zones. The findings indicated that the conflict rate on MLs was 48% and 11% lower than that of general purpose lanes (GPLs) in the peak and the off-peak periods, respectively. A log-linear model was developed with estimation of odds multipliers for the conflict frequency analysis. The results suggested that one accessibility level was the safest option in the 14.5-km (9-mi) corridor. The length of 35 m (1, ft) per lane change was shown to be the safest weaving length near access zones. Additionally, a weaving length of 183 m (6 ft) per lane change was not recommended. The findings of this study represent a further step toward improving access design of MLs.