Right-turn-on-red volume estimation and incremental capacity models for shared lanes at signalized intersections

The Highway Capacity Manual (HCM) is one of the most widely used transportation references in the world. It provides methods for the analyses of transportation system components such as freeways, multilane highways, two-lane highways, urban streets, signalized intersections, and others. The Signalized Intersections Methodology is used to estimate capacity and average control delay for individual lane groups and for intersections. The current method does not estimate control delay for vehicles that are permitted to turn right on red, nor does it include these vehicles in the computation of capacity. Furthermore, it provides limited guidance for estimating the number of right-turns-on-red (RTORs) when the actual number is unknown.;It is recognized that RTORs do increase the capacity of individual lane groups and the intersection as a whole. The result is that capacity, delay and level of service may not be predicted accurately when RTORs occur. This research focused on the specific case where RTORs occur from a shared lane. While RTORs in both cases are limited by the frequency of available gaps in conflicting traffic streams, the number and incremental capacity of RTORs from a shared lane are further affected by the proportion of through and right-turning vehicles. The objective of this research was to develop models that predict the number of RTOR vehicles and estimate their incremental capacity.;The RTOR Volume Estimation Model is a deterministic model that produced reasonable results and incorporates the probabilistic nature of RTORs from shared lanes. The model compared favorably with results obtained through simulating the anticipated number of RTORs that occurred at actual study sites. The RTOR Incremental Capacity Model demonstrated that greater capacity is realized when RTORs occur from shared lane approaches compared to the current HCM method. Both models developed are consistent with the current deterministic models contained in the HCM and have been validated with actual field data, enhancing their potential acceptance into future updates to the method. Finally, recommendations for adapting these models to intersection approaches with exclusive right-turn lanes were provided.;KEYWORDS:Right-Tums-on-Red (RTORs), Volume Estimation, Capacity, Shared Lanes, Signalized Intersections...