Modeling delay at signalized intersections with channelized right-turn lanes considering the impact of blockage

This paper presents a probabilistic delay model for signalized intersections with right-turn channelization lanes considering the possibility of blockage. Right-turn channelization is used to improve the capacity and to reduce delay at busy intersections with a lot of right-turns. However, under heavy traffic conditions the through vehicles will likely block the channelization entrance that accrues delay to right-turn vehicles. If the right-turn channelization gets blocked frequently, its advantage in reducing the intersection delay is neglected and as a result the channelization lane becomes inefficient and redundant. The Highway Capacity Manual (HCM) neglects the blockage effect, which may be a reason for low efficiency during peak hours. More importantly, using HCM or other standard traffic control methods without considering the blockage effects would lead to underestimation of the delay. To overcome this issue, the authors proposed delay models by taking into account both deterministic and random aspects of vehicles arrival patterns at signalized intersections. The proposed delay model was validated through VISSIM, a microscopic simulation model. The results showed that the proposed model is very precise and accurately estimates the delay. In addition, it was found that the length of short-lane section and proportion of right-turn and through traffic significantly influence the approach delay. For operational purposes, the authors provided a step-by-step delay calculation process and presented approach delay estimates for different sets of traffic volumes, signal settings, and short-lane section lengths. The delay estimates would be useful in evaluating adequacy of the current lengths, identifying the options of extending the short-lane section length, or changing signal timing to reduce the likelihood of blockage. Copyright (C) 2016 John Wiley & Sons, Ltd.