Speeds of Right-Turning Vehicles at Signalized Intersections during Green or Yellow Phase

Fitzpatrick, Kay; Pratt, Michael P.; Avelar, Raul

doi:10.1177/03611981211011642

Cited by 6 publications

(5 citation statements)

References 11 publications

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“…Although corner radius is objective and easy to measure, the presence of shoulders, parking lanes, bike lanes, and multiple receiving lanes can all allow a driver to have a far wider turning radius than what a corner radius might imply. The authors indicate that the model was built on data from sites in Dallas, Bryan, and College Station, TX, where no bike or parking lanes were present on the approach or the receiving leg, all sites were at right-angle intersections, more than 90% had more than one receiving lane, and sites with complex curvature or a channelized turn island were excluded from the study ( 25 ). From drawing vehicle turning paths in AutoCAD for intersections with those conditions, we found that the turning radius was always about 31-ft greater than the corner radius.…”

Section: Recommended Model Parameter Values and Acceleration Profilementioning

confidence: 99%

Head Start in Time or in Space? Determining Needed Leading Pedestrian Interval Length as a Function of Intersection Layout

Saeidi-Razavi

Furth

2023

Transportation Research Record: Journal of the Transportation R

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Where signalized pedestrian crossings run concurrently with vehicles, the permitted conflict between right-turning vehicles and pedestrians can be mitigated by giving pedestrians a head start. With a head start, pedestrians can establish themselves in the crosswalk before right-turning traffic can get there, reinforcing pedestrians’ priority and engendering better motorist yielding behavior. In some U.S. cities, it is becoming common to give pedestrians a head start “in time” by means of a leading pedestrian interval (LPI); however, pedestrians can also be given a head start “in space” using corner bulbouts, setback stoplines, and other protected intersection features that increase the distance from the pedestrian stopline to the vehicle stopline. A model was developed for determining the necessary LPI length as a function of an intersection’s corner geometry. Model elements include determining the path of a right-turning vehicle, defining the conflict zone, determining maximum vehicle speed, and modeling vehicle acceleration, so that vehicle and pedestrian time to reach the conflict zone can be determined. Application to a particular intersection showed that with (a) traditional corner geometry, (b) corner bulbouts added, and (c) a protected intersection layout, necessary LPI was 3.7, 1.1, and 0 s, respectively. The benefits of replacing an LPI with a head start in space included greater vehicle capacity and reduced cycle length, which in turn reduced pedestrian-, transit-, and vehicle delay and improved pedestrian compliance. To fully achieve these benefits, the Manual on Uniform Traffic Control Devices should consider eliminating its recommended minimum of 3 s for an LPI.

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Section: Recommended Model Parameter Values and Acceleration Profilementioning

confidence: 99%

Head Start in Time or in Space? Determining Needed Leading Pedestrian Interval Length as a Function of Intersection Layout

Saeidi-Razavi

Furth

2023

Transportation Research Record: Journal of the Transportation R

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“…For right-turn conflicts, corner radius categories (small, medium, large) are also considered as a proxy for turn speeds. This is because a large corner radius results in higher vehicle turning speeds, and recent research shows that, all else being equal, higher pedestrian crashes are expected at intersections with an increase in corner radius ( 12 ). Note that corner radius categories are used to make the calculation simple rather than requiring an analyst to the measure corner radius and estimate the associated turn speed.…”

Section: Performance Metrics Developmentmentioning

confidence: 99%

Multimodal Intersection Signal Timing Considerations Framework, Performance Measures, and Case Study

Cesme¹,

Hayes²,

Wang³

et al. 2023

Transportation Research Record: Journal of the Transportation R

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Signal retiming is a cost-effective practice to improve intersection operations through periodic updating of the timing plans. Traditionally, signal retiming has focused on vehicular-based performance (e.g., reducing vehicle delay or number of stops), while often unintentionally ignoring the needs of other users, such as pedestrians, cyclists, and transit vehicle passengers. This unintended omission is further exacerbated by the signal timing tools used in the industry, which tend to primarily report vehicular metrics. To address these challenges, this research developed a multimodal signal timing framework along with easy-to-use performance measures. These performance measures include (1) vehicle delay, (2) crosswalk delay, (3) crossing stress, and (4) bus delay. To assess the approach effectiveness, the proposed framework and the developed tools were applied to 12 intersections along the North Glebe Corridor, in Arlington, VA, for the weekday a.m. peak. Analysis results showed that the proposed framework and tools can incorporate most multimodal considerations and address the limitations of the traditional vehicle-based approaches by quantifying multimodal tradeoffs at signals. With the proposed tools, the alternative timing plan developed for the a.m. peak yielded a 4.5% improvement in performance along the corridor, versus a degradation of 3.7% if only vehicle delay was considered in the analysis. Additional sensitivity analysis conducted along the corridor using various timing plan scenarios showed that the calculated values of the measures are accurately reflecting the anticipated effects of signal timing changes that aim to improve crossing stress for non-motorized users and/or reduce their delay at the intersection crosswalks.

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“…For turning vehicles, however, the tasks are complicated since the geographical trajectory planning and calculation should generate both speed/acceleration and turning angle profiles, which needs to determine the turning pattern and the turning radius first. In this stage, the variety in vehicle sizes [21], planning algorithms [22], intersection geometric property [23][24][25], and desired turning speeds [21,26,27] directly leads to different turning patterns and radiuses, referring to variation in both vehicle position and speed trajectories. In the trajectory tracking and maneuvering, the speed and turning angle are required to be adjusted simultaneously.…”

Section: Introductionmentioning

confidence: 99%

Simulation-Based Evaluation of Variation in Left-Turn Paths in the Coordinated Intersection Management

Yang

Bai

2021

Journal of Advanced Transportation

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Coordinated intersection management (CIM) has gained more attention with the advance of connected and autonomous vehicle technology. The optimization of passing schedules and conflict separation between conflicting vehicles are usually conducted based on the predefined travelling paths through the intersection area in the CIM. In real-world implementation, however, the diversity of turn paths exists due to multiple factors such as various vehicle sizes and automation control algorithms. The aim of this paper is to investigate how the variation in left-turn paths affects the feasibility and viability of optimal passing schedules, as well as the safety and efficiency of intersection operation. To do this, we start with identifying six typical left-turn paths to represent the variation. A scenario-based simulation is first conducted by using each of the paths as the nominal path. The optimal schedules and the corresponding alternative schedules are generated to calculate indicators for nominal performance, average performance, and robustness. The best path is selected in terms of schedule optimality and robustness. With schedules obtained by solving CIM models using the selected path, the left-turning CAVs are assumed to travel along one of the six paths randomly to simulate the path divergence. A surrogate safety measure, PET, is utilized to assess the safety of the intersection under CIM. The theoretical PET with the nominal path and the actual PET with the random path are calculated for each conflict event. Comparisons of two PET sets show the increase in conflict risk and vehicle delay. The conclusion can be drawn that the variation in left-turn paths causes the decline in safety level and travelling efficiency and should be considered in the CIM model to ensure safe and efficient implementation in the intersection.

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Speeds of Right-Turning Vehicles at Signalized Intersections during Green or Yellow Phase

Cited by 6 publications

References 11 publications

Head Start in Time or in Space? Determining Needed Leading Pedestrian Interval Length as a Function of Intersection Layout

Head Start in Time or in Space? Determining Needed Leading Pedestrian Interval Length as a Function of Intersection Layout

Multimodal Intersection Signal Timing Considerations Framework, Performance Measures, and Case Study

Simulation-Based Evaluation of Variation in Left-Turn Paths in the Coordinated Intersection Management

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