Models for Lane Utilization Prediction for Lane Drop Intersections

Abstract

Lane drops downstream of signalized intersections can be found on many urban and suburban streets and highways. Because drivers tend to avoid using the short lane because of the potential for stressful merges downstream of the signal, the short lane is typically underused. Previous research indicates that the default lane utilization factors in the Highway Capacity Manual (HCM) appear to overestimate traffic in the short lane. The purpose of this research is to develop models to predict lane utilization factors for six intersection types and to assess how low lane utilization affects the observed intersection capacity and level of service. Traffic and signal data were collected at 47 sites in North Carolina. On the basis of 15 candidate factors, multiple regression models were developed for predicting the lane utilization factor. Field-measured delays were compared with delays estimated by the HCM with the use of regression models for lane utilization. It was found that even with the new models for lane utilization, the HCM consistently overestimated delay for all types of lane drop intersections with low lane utilization: a reassessment of the effect of lane utilization on capacity may be in order. This study also found that the downstream lane length and traffic intensity positively correlate with the lane utilization factor and that some geometric variables at the approach may also influence lane utilization.