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

Abstract

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.

Impact of Guideline Markings on Saturation Flow Rate at Signalized Intersections

“…Referring to the adjusted saturation flow rate model of HCM 2010 [15], the ratio of the saturation flow rate at an intersection with guideline markings to an intersection without guide line markings can be defined as the adjustment factor for guide line markings, as shown in (2). By studying the relationship between the adjustment factor and other factors, including the traffic flow direction, number of lanes, offset for through movement, and turning angle for left-turns, the model can be adapted to determine the adjustment factor for guide line markings under different conditions: where S is the saturation flow rate per lane at a signalized intersection with guideline markings, veh/h/ln; 0 is the saturation flow rate per lane at a signalized intersection without guideline markings, veh/h/ln; and is the adjustment factor for the guideline markings.…”

“…There are two common methods to solve these problems: intersection design and standardization of cross-road intersections and traffic channelization measures such as the traffic signs and markings shown in Figure 1(c) [2][3][4]. Many studies have shown that traffic signs and markings can be effectively used to regulate, warn, and guide road users [5][6][7][8][9][10][11].…”

Evaluation of Delay Characteristics at Signalized Intersections for Improvement in Level of Service

“…The study concluded that changes in phasing plan with geometric improvement would improve upon the intersection's level of service. (Farivar and Tian, 2016) explained the probabilistic delay model for signalized intersections w ith right-turn channelization lanes considering the possibility of blockage. Many traffic simulation models are used in various combinations to quantify the traffic signals characteristics.…”

Capacity Analysis of Intersections When CAVs Crossing in a Collaborative and Lane-Free Order

“…There are extensive prior works to characterise the capacity of intersections for HVs (e.g. [1,2,3]), however, such analysis for CAVs in a lane-free order is still an open research topic.…”