Safety Performance of Flashing Yellow Arrow for Protected–Permissive Left-Turn Signal Control in Central Illinois

Schattler, Kerrie L; Anderson, Eric P.; Hanson, Trevor

doi:10.3141/2636-05

Cited by 6 publications

(8 citation statements)

References 4 publications

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“…Two sets of results were reported for each category-the ''first set'' only included intersections that were exclusive to that category, and the ''second set'' included all legs that belonged to that category. The categories along with the CMFs are provided below: (6). The evaluation included 86 intersections where the state had implemented FYA on 164 approaches.…”

Section: Literature Reviewmentioning

confidence: 99%

Crash Modification Factors for the Flashing Yellow Arrow Treatment at Signalized Intersections

Srinivasan

Lan

Carter

et al. 2018

Transportation Research Record

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This paper presents the results of an evaluation of the flashing yellow arrow (FYA) treatment using data from signalized intersections in Nevada, North Carolina, Oklahoma, and Oregon. The evaluation method was an empirical Bayes before–after analysis. The treatments were divided into seven categories depending on the phasing system in the before period (permissive, protected–permissive, or protected), phasing system in the after period (FYA permissive or FYA protected–permissive), the number of roads where the FYA was implemented (one road or both roads), and the number of legs at the intersections (three or four). The first five treatment categories involved permissive or protected–permissive phasing in the before period. Intersections in these five treatment categories experienced a reduction in the primary target crashes under consideration: left turn crashes and left turn with opposing through crashes. The reduction ranged from 15% to 50%, depending on the treatment category. Intersections that had at least one protected left turn phase in the before period and had FYA protected–permissive left turn phase in the after period experienced an increase in left turn crashes and left turn with opposing through crashes, indicating that replacing a fully protected left turn with FYA will likely cause an increase in left turn crashes.

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Section: Literature Reviewmentioning

confidence: 99%

Crash Modification Factors for the Flashing Yellow Arrow Treatment at Signalized Intersections

Srinivasan

Lan

Carter

et al. 2018

Transportation Research Record

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“…More recently, supplementary signage was evaluated in parallel to FYA installation in a four-and fivesection signal. In this study by Schattler et al, the results found that supplemental signage has a need in assisting driver comprehension with the FYA indication (13). Research continues to prosper in this area as safety impacts of the implementation of the FYA continue to emerge.…”

Section: Effects Of Fya Driver Comprehension and Supplementary Signagementioning

confidence: 82%

“…Rietgraf et al found that there was no significant difference in having areas with one permissive indication for left-turns compared to areas with multiple permissive left-turn indications; however, that evidence suggests consistency in permissive indications may yield a stronger comprehension rate (11). In addition to this, researchers continue to focus on the comprehension of supplementary signage with the FYA left-turn indication (12), (13).…”

Section: Effects Of Fya Driver Comprehension and Supplementary Signagementioning

confidence: 99%

All-Red Clearance Intervals for Use in the Left-Turn Application of Flashing Yellow Arrows

Tainter

Christofa

Knodler

2020

J. Transp. Eng., Part A: Systems

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With the advancement of implementation for a novel traffic control device, the Flashing Yellow Arrow (FYA), agencies across the country have continually sought strategies to improve intersection operations and safety, specifically with respect to the left-turn application. More so, permissive left-turn intervals have been communicated to drivers using several traffic signal indications; however, most frequently these phases are represented through the circular green (CG) ball and more recently, the FYA. Previous research in this area determined that the FYA indication produced the most effective communication of permissive left-turns. Further, this previous research led to the inclusion of the FYA in the 2009 edition of the Manual on Uniform Traffic Control Devices (MUTCD). In recent years, agencies across the country have embraced the implementation of the FYA for permissive left-turns. However, there remains a lack of national guidance on the definition of change and clearance intervals for transitioning between protected and permissive left-turns. Complicating the matter is the connection between traditional signal phasing/design and human factors. Investigation through driver comprehension and real-world operations will allow us to not only evaluate current conditions, but also experimental and future conditions. Recommendations provided from this research will ultimately offer agencies with the strategies for the most effective transition from a protected left-turn to a permissive left-turn phase. v

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“…A study of a site in Austin, Texas examined the change in number of crashes ( 18 ); however, documentation of speed of turning vehicles before and after such an improvement was not reported. A study in Peoria, Illinois ( 19 ) included the observation of driver behavior along with evaluating the change in crashes caused by modifications of the right-turn approaches. Field observations of driver behavior at the right-turn lanes at 10 test sites and 10 control sites were collected.…”

Section: Review Of Literaturementioning

confidence: 99%

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

Fitzpatrick

Pratt

Avelar

2021

Transportation Research Record

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The operation and design of signalized intersections involves tradeoffs between operational efficiency and safety for a variety of users, including motorists, pedestrians, and bicyclists. Additionally, the mix of vehicle types in the fleet sometimes requires special considerations. These concerns especially apply to the selection of curb radius at the corners, where right-turning vehicles operate close to pedestrians. Larger curb radii accommodate the swept paths of trucks and allow right turns to occur at higher speeds but may compromise safety and security for pedestrians by increasing the crossing distance and increasing the frequency of higher-speed turns. The authors collected right-turn vehicle speeds at 31 urban signalized intersection approaches in Texas with radii ranging from 15 to 70 ft. The authors calibrated a model to predict right-turn speeds as a function of site characteristics including curb radius, leading headway, vehicle type (car versus truck), maneuver of the preceding vehicle (through versus right turn), and signal indication (yellow or green). The analysis results indicate that right-turn speeds increase slightly with increasing radius, if the preceding vehicle proceeds through (rather than turning right) at the intersection, or if the signal indication is yellow rather than green. The calculated 85th percentile turning speed is generally higher than the assumed speed calculated using the radius of curvature equation. These trends should be considered if the intersection is expected to have notable volumes of pedestrians or trucks, as lower speeds are desirable for pedestrian safety, but larger radii may be necessary to accommodate turning trucks.

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Safety Performance of Flashing Yellow Arrow for Protected–Permissive Left-Turn Signal Control in Central Illinois

Cited by 6 publications

References 4 publications

Crash Modification Factors for the Flashing Yellow Arrow Treatment at Signalized Intersections

Crash Modification Factors for the Flashing Yellow Arrow Treatment at Signalized Intersections

All-Red Clearance Intervals for Use in the Left-Turn Application of Flashing Yellow Arrows

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

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