Optimizing signal phase plan, green splits and lane length for isolated signalized intersections

Abstract

Abstract.At an isolated signalized intersection, short left-turn lanes may be provided to enhance intersection capacity and level of service. The capacity of an entire intersection depends not only on the effective green time per phase and the length of each short left-turn lane but also on the selected signal phase plan. This paper enumerates 16 typical signal phase plans for a four-leg intersection with protected left-turn phases. Given the existence of short left-turn lanes and the freedom to select signal phase plans, two optimization models are formulated. Numerical examples are carried out to illustrate the application of these models and show the sensitivity of the outcomes to impact factors. The orthogonal experiments show that the primary factor is whether a short left-turn lane is added on an approach and the demand distribution is the secondary factor in determining an optimal allocation of the time-space resources of an intersection. To analyse traffic flow operations under different signal phase sequences, the simulation tests are fulfilled using VISSIM under the assumption that the components of a signal phase plan and green splits are all identical. The simulated results indicate that the signal phase sequence for a specified approach may greatly affect traffic movements at an approach, and the leading green phasing is better than the lagging one for a specified approach when the left-turn bay length is short at the approach. Finally, two variations of the developed models are recommended for use and the procedure for the model application is provided in practice.

Comparative Analysis of Optimization Models for Paired Intersections with Left-Turn Bays

“…For each ring (i.e., the east-west or south-north direction) at each intersection, Figure 1(b) shows the four possible combinations of signal phasing, that is, leftthrough phasing, exclusive left-turn phasing, leading and lagging green phasing, and exclusively left-turn plus leading green phasing [20]. Left-through phasing means that the subject left-turn and through movements simultaneously have or lose right-of-way, whereas exclusive left-turn phasing means that the subject and opposing left-turn movements simultaneously have or lose right-of-way.…”

“…For signalized intersections, the effective green time per phase is a decision variable to represent the allocation of temporal resources, while the length of each left-turn bay is a decision variable to represent the allocation of spatial resources [18][19][20]. e abovementioned research only focused on left-turn bays at isolated intersections.…”

Use of Universal Simulation Software Tools for Optimization of Signal Plans at Urban Intersections

“…Köhler also points out how some methods of mathematical programming, namely mixed-integer linear programming, can be used for traffic light optimization, while also solving the optimal share of the green wave within a 1-time cycle, the so-called green split and optimization of the order of individual phases [7]. The same issues concerning the optimization of phases and the percentage of green wool, independently of Köhler, are also addressed by Yao, Zhou and Ge [8]. In their study, however, they also consider the presence of the turn lane and its length and compare different approaches to optimization for intersections with or without turn lanes.…”

Traffic Assessment And Optimization at Signalized Intersections: A Review Study

“…Hasan (2019) stated that after implementing the proposed geometrical design, Al-Faris Al-Arabee intersection in Baghdad city is going to operate at LOS B for the existing condition and LOS D in the design year (2039). Yao et al (2018) discovered that optimum outcomes and related intersection performance are influenced by demand distribution as well as intersection structure. It is also found that the signal phase sequence can considerably affect intersection performance.…”