The Effect of the Number of Right-Turn and Left-Turn Lanes on the Performance of Undersaturated Signalized Intersections

Abstract

Vehicle traffic flow channelizing can significantly contribute to fewer collisions and smooth traffic flow in isolated signalized intersection design. Therefore, this study investigates the effect of changes in the number of right-turn lanes with splitter islands and left-turn storage bays for different volume approaches on intersection performance. This study aims to provide an accurate analysis to estimate the effect of such changes on signalized intersections, which can improve intersection performance. Furthermore, the delay parameter derived from HCM2016 and simulation was evaluated for different scenarios. For this purpose, simulation was performed using Synchro software. In this study, a symmetrical, 90-degree, undersaturated (volume per capacity lower than 1, V/C < 1), and four-leg intersection were considered according to AASHTO Green Book 2018 suggestions. HCM2016 results indicated the delay parameter was less sensitive to the undersaturated condition than the right-turn volume variation for both single and dual-lane bays. However, the simulation results indicated that the delay parameter was not constant, depending on the number of right-turn lanes and volumes. On the other hand, there was a significant difference in delay parameters between the single and dual left-turn lanes for both simulation and HCM cases estimated 77.4% and 59.7%, respectively. Overall, this study can provide a vision for traffic engineers to modify the geometry of the four-leg signalized intersections, if the right-turn or left-turn demand volume of an undersaturated signalized intersection is larger than the through approach.

Platoon-Based Assessment of Two-Way Two-Lane Roads Performance Measure: A Classification Method

“…An examination of the previous studies on the capacity of two-lane roads reveals that these studies have primarily concentrated on three key aspects: LOS and capacity, platoon changes, and time headway and spacing headway. In the frst group of the aforementioned studies, several research works have investigated the infuence of various parameters, such as the number of platoons formed by vehicles [11], the HV [12][13][14] [15], the NFPC [16,17], speed of followers and critical H t as functional characteristics [18,19], the PTSF and the ATS [20][21][22], geometric parameters (longitudinal slope and superelevation of the road) [23,24], geometric features of the road and trafc conditions (density, speed, and the trafc fow rate) [25][26][27], and density [28] and travel speed using passenger car equivalent [29] on the LOS and road capacity.…”

A Conflict-Based Safety Diagnosis of SCI Roundabouts Using a Surrogate Safety Measure Model

“…Due to many collision points, urban intersections are among the most critical places for accidents. Safety at intersections can be improved through the design of roundabouts [1,2]. A comparison between traditional intersections and roundabouts reveals that the severity of crashes in roundabouts is lower [3].…”