Direct and Indirect Effect of the Flashing Yellow Arrow Signal for Left-turn Traffic on Safety at Signalized Intersections PDF Download
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Author: Khamar Salma Chittoor Khader Publisher: ISBN: Category : Languages : en Pages : 132
Book Description
develop safety performance functions (for left-turn as well as total number of crashes). The estimated number of left-turn and total number of crashes, had FYA signals not been installed, were then compared to the actual number of left-turn and total number crashes that occurred at the study intersections.Negative Binomial (log-link) distribution was observed to be a better fit to develop safety performance functions than Poisson (log-link) distribution. The results obtained indicate that FYA signals, in general, help reduce left-turn crashes (direct effect) as well as the total number of crashes (indirect effect) and contribute to improved safety at signalized intersections. They do not seem to be suitable for intersections with heavy-traffic volume.
Author: Khamar Salma Chittoor Khader Publisher: ISBN: Category : Languages : en Pages : 132
Book Description
develop safety performance functions (for left-turn as well as total number of crashes). The estimated number of left-turn and total number of crashes, had FYA signals not been installed, were then compared to the actual number of left-turn and total number crashes that occurred at the study intersections.Negative Binomial (log-link) distribution was observed to be a better fit to develop safety performance functions than Poisson (log-link) distribution. The results obtained indicate that FYA signals, in general, help reduce left-turn crashes (direct effect) as well as the total number of crashes (indirect effect) and contribute to improved safety at signalized intersections. They do not seem to be suitable for intersections with heavy-traffic volume.
Author: Kailas Venkitasubramanian Publisher: ISBN: Category : Languages : en Pages : 132
Book Description
This thesis evaluated the effectiveness of flashing yellow arrow (FYA) permitted left-turn signals in reducing conflicts and events at intersections. A FYA permissive signal is a recent treatment used as an alternate to circular green signal at signalized intersections. It is the newest addition to the series of permitted left-turn signal indicators and has been designed to improve the clarity of indication among drivers. The signal is expected to result in safer turning movements during the permitted phase. Conflict data was collected during morning peak period (7:00 AM to 9:00 AM) and evening peak period (4:00 PM to 8:00 PM) at four study intersections in Charlotte. Data was collected before the installation of FYA signal was introduced and after one month, three months and six months of installation of FYA. Relevant types of conflicts and events associated with left-turn maneuver were observed and recorded. Descriptive statistics, proportions of conflicts/events and statistical tests were conducted to analyze the data collected. Conflicts and events were also analyzed separately for each intersection using various comparison sets to understand their trend over time and the impact of FYA on them. Observations and analysis indicated that benefits in terms of reduction in conflicts and events are substantial at 7th Street / 5th Street intersection and Mallard Creek Church Road / 1-85 Southbound interchange but are marginal and currently statistically insignificant at Sunset Road / 1-77 interchanges. Overall, FYA leaves a positive effect on the intersection safety, helps reduce vehicular conflicts/events and is suitable for application at other intersections in the future.
Author: Raghavan Srinivasan (Transportation engineer) Publisher: ISBN: Category : Electronic traffic controls Languages : en Pages : 54
Book Description
This study evaluated the safety effect of the flashing yellow arrow (FYA) treatment at signalized intersections. The major objective of this strategy is to reduce the frequency of left-turn (LT) crashes, especially those that involve a collision between left turns and vehicles traveling straight through from the opposite direction. The project team conducted an empirical Bayes before-after analysis of installations in Nevada, North Carolina, Oklahoma, and Oregon. The treatments were divided into seven categories depending on the phasing system in the before and after periods, number of roads where FYAs were implemented, and number of legs at each intersection. The first five 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: LT crashes and left-turn-with-opposing-through (LTOT) crashes at the intersection level. The reduction ranged from 15 to 50 percent depending on the treatment category. Intersections in categories 6 and 7 had at least one protected LT phase in the before period, and after phasing had an FYA protected-permissive LT phase without time-of-day operation (category 6) and with time-of-day operation (category 7). Consistent with results from previous studies, these intersections experienced an increase in LT and LTOT crashes. The B/C ratios for categories 1-5 ranged from 56:1 to 144:1.
Author: Raghavan Srinivasan Publisher: ISBN: Category : Electronic traffic controls Languages : en Pages : 0
Book Description
This study evaluated the safety effect of the flashing yellow arrow (FYA) treatment at signalized intersections. The major objective of this strategy is to reduce the frequency of left-turn (LT) crashes, especially those that involve a collision between and vehicles traveling straight through from the opposite direction.--Abstract.
Author: Hugh W. McGee Publisher: Transportation Research Board ISBN: 0309258596 Category : Traffic safety Languages : en Pages : 93
Book Description
TRB National Cooperative Highway Research Program (NCHRP) Report 731: Guidelines for Timing Yellow and All-Red Intervals at Signalized Intersections offers guidance for yellow change and all-red clearance intervals at signalized intersections. The guidelines provide a framework that can be easily applied by state and local transportation agencies.
Author: Florida. Department of Transportation. Research Center Publisher: ISBN: Category : Traffic signs and signals Languages : en Pages : 89
Book Description
There is a need to develop an interactive and efficient framework to serve as a decision support system (DSS) for the evaluation of left-turn phasing alternative based on intersection conditions. This framework will allow (1) an interactive evaluation of left-turn phasing and ultimately recommend phasing mode by time-of-day and (2) Traffic Management Center (TMC) data to be fed into the DSS so that intersections requiring attention/modification of left-turn mode can be flagged. The current study develops an interactive DSS for assessing the likely benefits of warranting a permitted left-turn phase using custom design approach. The developed DSS is designed to predict these benefits based on multilevel factorial parameters that are practical and applicable to assist TMCs in evaluating the efficiency of a permitted left-turn phase by time of day.
Author: Khamar Salma Chittoor Khader
Author: Khamar Salma Chittoor Khader
Author: Kailas Venkitasubramanian
Author: Raghavan Srinivasan (Transportation engineer)
Author: H. A. Mike Flanakin
Author: Raghavan Srinivasan
Author: 
Author: Hasan Ozer
Author: Min Zhang
Author: Hugh W. McGee
Author: Florida. Department of Transportation. Research Center