Operational Impacts of Protected-Permitted Right-Turn Phasing and Pavement Markings on Bicyclist Performance during Conflicts with Right-Turning Vehicles

2019 ◽  
Vol 2673 (4) ◽  
pp. 789-799
Author(s):  
Masoud Ghodrat Abadi ◽  
David S. Hurwitz
Keyword(s):  
Traffic Control ◽  
Safety Concern ◽  
Lateral Position ◽  
Signalized Intersections ◽  
Pavement Markings ◽  
Conflict Area ◽  
Flashing Yellow Arrow ◽  
Mixed Factorial Design ◽  
Operational Impacts ◽  
Yellow Arrow

Conflict between bicycles and right-turning vehicles on the approach to signalized intersections is a critical safety concern. To understand the operational implications of protected-permitted right-turn signal indications in conjunction with pavement markings on bicyclist performance, a full-scale bicycling simulator experiment was performed. Velocity and lateral position of bicyclists were evaluated during conflicts between bicycles and right-turning vehicles. A mixed factorial design was considered. Two within-subject factors were analyzed: the signal indication for right-turning vehicles with five levels (circular red, circular green, solid red arrow, solid green arrow, and flashing yellow arrow), and the pavement markings in the conflict area with two levels (white lane markings with no supplemental pavement color and white lane markings with solid green pavement applied in the conflict area). Additionally, the influence of gender as a between-subject variable was considered. Forty-eight participants (24 female) completed the experiment. Signal indications and pavement markings had statistically significant effects on bicyclist velocity and lateral position, but these effects varied at different factor levels. Additionally, during the conflicts, male participants were found to have higher velocity than female participants. This difference was not influenced by engineering treatments. The results provide guidance to transportation professionals about how traffic control devices could be applied to conflict areas on the approach to signalized intersections.

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

2018 ◽  
Vol 2672 (30) ◽  
pp. 142-152 ◽  
Author(s):  
Raghavan Srinivasan ◽  
Bo Lan ◽  
Daniel Carter ◽  
Sarah Smith ◽  
Kari Signor
Keyword(s):  
North Carolina ◽  
Empirical Bayes ◽  
Evaluation Method ◽  
Signalized Intersections ◽  
Left Turn ◽  
Flashing Yellow Arrow ◽  
Crash Modification Factors ◽  
Treatment Category ◽  
Using Data ◽  
Yellow Arrow

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.

Driving Simulators for Evaluation of Novel Traffic-Control Devices: Protected–Permissive Left-Turn Signal Display Analysis

2003 ◽  
Vol 1844 (1) ◽  
pp. 25-34 ◽  
Author(s):  
David A. Noyce ◽  
Christopher R. Smith
Keyword(s):  
Traffic Control ◽  
Driving Simulator ◽  
Driving Simulators ◽  
Left Turn ◽  
Flashing Yellow Arrow ◽  
Green Ball ◽  
Other Information ◽  
Control Devices ◽  
Research Show ◽  
Yellow Arrow

A study evaluated drivers’ comprehension of several experimental five-section protected–permissive left-turn (PPLT) signal displays. A full-scale driving simulator and static driver study were used. Study methods were compared while evaluating drivers’ comprehension and response to various combinations of five-section PPLT signal-display arrangements (horizontal, vertical, and cluster) and permissive left-turn indications (green ball, flashing red ball, flashing yellow ball, flashing red arrow, and flashing yellow arrow). The results showed that the type of five-section PPLT signal display arrangement has very little effect on driver comprehension of the permissive left-turn maneuver. The type of permissive indication used in five-section PPLT signal displays had a significant effect on driver comprehension, since the green ball, flashing yellow ball, and flashing yellow arrow were the best understood. When combining five-section PPLT signal-display arrangements and permissive indications, the five-section horizontal arrangement with a flashing-yellow-ball permissive indication had the highest level of driver comprehension. The lack of surrounding driving cues in the static driver study led to significantly higher fail-critical (serious) response rates. The green-ball permissive indication had a driver comprehension rate over 30% lower in the static study, clearly showing that drivers do not correctly comprehend the meaning of the green ball (assume it is protected) and use other information to make left-turn decisions while driving. The findings of this research show that driving simulation provides an effective study method and effectively replicates the actual driving environment. Simulators should be considered when conducting driver comprehension analyses.

Modifying Highway Capacity Manual Methodology for Inclusion of Flashing-Yellow-Arrow Delay and Suppression

2020 ◽  
Vol 2674 (12) ◽  
pp. 233-242
Author(s):  
Daniel J. Cook
Keyword(s):  
Sensitivity Analysis ◽  
Signalized Intersections ◽  
Signalized Intersection ◽  
Effective Strategy ◽  
Highway Capacity ◽  
Left Turn ◽  
Highway Capacity Manual ◽  
Flashing Yellow Arrow ◽  
Left Turns ◽  
Yellow Arrow

Dallas phasing is an effective strategy for increasing the efficiency of protected-permissive left turns (PPLTs) at signalized intersections, without creating left-turn traps. The flashing yellow arrow (FYA) is the most widely used PPLT signal indication when Dallas phasing is utilized. The Highway Capacity Manual (HCM) signalized intersection methodology currently contains guidance on how to handle PPLTs with Dallas phasing. At intersections with the FYA indication, some agencies have been using a feature known as FYA delay, which delays the FYA indication, usually by 1 to 4 s. More recently, some agencies have also began using another feature, which suppresses the FYA when a conflicting pedestrian phase is active. The HCM does not contain guidance on how to handle FYA delay or suppression. This research proposed modifications to the HCM signalized intersection methodology to address these two FYA strategies. A sensitivity analysis was conducted to check the reasonableness of the proposed modifications. The sensitivity analysis showed that the proposed modifications are reasonable and produced the expected results.

Evaluation of Flashing Yellow Arrow in Traffic Signal Displays with Simultaneous Permissive Indications

2005 ◽  
Vol 1918 (1) ◽  
pp. 46-55 ◽  
Author(s):  
Michael A. Knodler ◽  
David A. Noyce ◽  
Kent C. Kacir ◽  
Christopher L. Brehmer
Keyword(s):  
Traffic Control ◽  
Driving Simulator ◽  
Left Turn ◽  
Flashing Yellow Arrow ◽  
Research Findings ◽  
Computer Based ◽  
Control Devices ◽  
Common Application ◽  
Yellow Arrow ◽  
Comprehensive Study

The results of a comprehensive study on protected and permissive left-turn (PPLT) operations showed that the flashing yellow arrow (FYA) indication was an acceptable and recommended application for permissive left turns. As documented in NCHRP Report 493, an FYA permissive indication was recommended for implementation in the FHWA Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD). Research findings suggested that the FYA be implemented in an exclusive four-section vertical signal display centered over the left-turn lane, which differs from the most common application of PPLT signal displays. Many traffic engineers currently use a five-section clustered-arrangement shared signal head to meet MUTCD requirements of two signal heads per major approach. FYA implementation in the five-section display would require an interim retrofit requiring the FYA to be displayed simultaneously with the through-movement circular green (CG), circular yellow, or circular red indication. This research evaluated driver comprehension of the retrofit display and the resulting simultaneous indications by using a dynamic driving simulator and computer-based static experiments. A comparison of seven permissive left-turn scenarios featuring the CG or FYA permissive indications, or both, was completed. In total, 264 drivers evaluated 3,457 permissive left-turn scenarios. Results showed that simultaneous indications in the retrofit display did not affect the drivers’ understanding of the permissive indications. The drivers demonstrated an understanding of the yield requirement with simultaneous indications (with a 65% to 89% correct responses), providing evidence to suggest that the simultaneous indications would be suitable as an interim display to ease FYA implementation.

Evaluation of safety and operational impacts of bicycle bypass lanes at modern roundabouts

2008 ◽  
Vol 35 (10) ◽  
pp. 1025-1032 ◽  
Author(s):  
Essam Dabbour ◽  
Said M. Easa
Keyword(s):  
Traffic Signals ◽  
Signalized Intersections ◽  
Vision Impairment ◽  
Evaluation Scheme ◽  
Pedestrian Traffic ◽  
Negative Impacts ◽  
Operational Impacts ◽  
Full Utilization

Modern roundabouts have been found to improve safety and reduce overall delay, but they may have negative impacts on the safety of cyclists as other vehicles may cut-off cyclist paths while entering or exiting the roundabout. Several before–after studies have found an increase in traffic collisions involving cyclists at roundabouts after being converted from conventional signalized intersections. Another concern associated with roundabouts is the safety of pedestrians, especially pedestrians with severe vision impairment who may find difficulty in negotiating roundabouts. This paper evaluates safety and operational impacts of using bicycle bypass lanes at roundabouts as a means of increasing the safety of cyclists. The paper also recommends the full utilization of pedestrian traffic signals, proposed by other studies, by incorporating them with the proposed bicycle bypass lanes. An evaluation scheme involving the safety benefits and the costs of the proposed bypass lanes is provided to help practitioners decide when they are warranted. The evaluation scheme is illustrated using an application example.

Effects of Traffic Control Devices on Rural Curve Lateral Position

2021 ◽  
pp. 036119812110347
Author(s):  
Francesco Galante ◽  
Filomena Mauriello ◽  
Mariano Pernetti ◽  
Maria Rella Riccardi ◽  
Alfonso Montella
Keyword(s):  
Traffic Control ◽  
Driving Simulator ◽  
Statistical Tests ◽  
Field Tests ◽  
Relative Length ◽  
Lateral Position ◽  
Warning Signs ◽  
Performance Standard ◽  
Second Phase ◽  
Surrogate Measures

This study investigated, by means of a dynamic driving simulator experiment, road users’ behavior inside the curves of rural two-lane highways related to different advance warning signs, perceptual measures, and delineation treatments. These treatments were intended to warn drivers of the presence of low radius curves and to affect their behavior, improving vehicle control and lane-keeping. Five surrogate measures of safety were used in the evaluation of the design alternatives in relation to lateral position performance: standard deviation of lateral position, maximum encroachment in the shoulder, maximum encroachment in the opposite lane, relative length of shoulder encroachment, and relative length of opposite lane encroachment. Statistical tests were performed to verify whether the surrogate measures of safety were significantly different between alternatives. The analysis was divided into three phases. In the first phase, all the measures were preprocessed, testing normality and homoscedasticity assumptions. In the second phase, the presence of an overall effect considering all the alternatives was evaluated using analysis of variance and the Kruskal–Wallis test. In the third phase, Student’s t- and Mann–Whitney tests were used to assess which alternatives showed statistically significant effects. The results demonstrated that the perceptual measures, namely colored transverse strips, dragon teeth markings, and colored median island, were the most effective treatments. Field tests to establish the perceptual measures’ effectiveness on real roads are strongly advised. Implementation of the measures tested in the driving simulator should be carried out on similar rural highways to validate the results.

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