Authors: Liu Xu, Xianfeng Yang, Geng-len Chang and Saed Rahwanji
Conference: Presentation at 2015 TRB Annual Meeting
Unconventional Design: Signalized Superstreet
Purpose: Developed a set of interval-based queue models for evaluating the bay lengths among a signalized superstreet.
Despite the extensive implementations of Superstreets on congested arterials, a reliable tool for effective assessment of their geometric designs remains unavailable in the literature. To satisfy such a need, this study presents a convenient planning method that allows users to reliably estimate the queue size and its variation (interval) on each critical link in a Superstreet, based on the given signal plan and observed range of volumes. Grounded on a set of simulation experiments with well-calibrated network, this study also shows the significant interrelations between intersection delay and link occupancy rates by traffic queues. Hence, the estimated queue intervals in comparison with the proposed link length offers the basis for design engineers to evaluate if any queue spillover and lane blockage may occur on any critical links, and to determine if the preliminary geometric design needs to be revised, or the signal coordination between a Superstreet’s sub-intersections shall be redesigned. To assess the proposed model’s effectiveness, the study further conducts a simulation evaluation with the field data from a Superstreet in Maryland, and the results of extensive experiments confirm the reliability and applicability of the proposed model in evaluating the design of Superstreet.