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Intersection Safety Strategies Brochure (FHWA)

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SIGNALIZED INTERSECTION SAFETY STRATEGIES CATEGORY A: REDUCE CATEGORY D: IMPROVE DRIVER 2013 INTERSECTION FATALITIES FREQUENCY AND SEVERITY AWARENESS OF INTERSECTIONS OF INTERSECTION CONFLICTS AND SIGNAL CONTROL THROUGH TRAFFIC CONTROL lD1 – Improve visibility of intersections Signalized 3,338 AND OPERATIONAL on approach(es) IMPROVEMENTS Where to use - Signalized intersections with a high frequency of crashes attributed to Unsignalized 5,760 lA1 – Replace permissive left turns drivers being unaware of the presence of the with protected left turns intersection. Where to use - Signalized intersections with a high frequency of angle crashes ? Other/Unknown 235 involving left turning and opposing through vehicles. A properly timed protected left- lD2 – Improve visibility of signals and signs at intersections turn phase can also help reduce rear-end and sideswipe crashes between left-turning Where to use -Signalized intersections with a high frequency of right-angle and 0 1,000 2,000 3,000 4,000 5,000 6,000 vehicles and the through vehicles behind them. rear-end crashes occurring because drivers are unable to see traffic signals and signs Source: FARS, National Highway Traffic Safety Administration (2013). Available: http://safety.fhwa.dot.gov/intersection/resources/intsafestratbro/intersection_guide12.pdf Keywords: protected, permissive, signal phasing SIG sufficiently in advance to safely negotiate the intersection being approached. Keywords: signal visibility SIG lA2 – Optimize change and clearance intervals SIGNALIZED COST Where to use - Signalized intersections with a high frequency of crashes related to lD3 – Install/add one signal head per lane change interval lengths that are possibly too short. These crashes include angle Where to use - Signalized intersections with a high frequency of crashes caused by SAFETY CONCERN lLow lModerate lHigh High frequency of right-angle crashes crashes between vehicles continuing through the intersection after one phase has driver indecision in lane assignment. SIG ended and the vehicles entering the intersection on the following phase. Rear-end Keywords: add signal, signal head attributed to: crashes may also be a symptom of short change intervals. nearby driveways F2 F1 Keywords: change interval, signal phasing, signal timing SIG lD4 – Install larger 12” signal heads traffic from cross street A2, A3 E2 Where to use - Signalized intersections with a crash history or observed conflicts skewed intersection lA3 – Restrict or eliminate turning maneuvers involving lack of awareness of the intersection or traffic control and observed speeding Where to use - Signalized intersections with a high frequency of crashes related to on approaches to the intersection. poor sight distance A1, C1, G5 C2, G4 B3 Keywords: signal lense, signal head SIG turning maneuvers. For right turn on red (RTOR), the target of this strategy is right- drivers misjudging gaps A1 turning vehicles that are involved in rear-end or angle crashes with cross-street vehicles not enough gaps for drivers A1 A4, B4 approaching from the left or vehicles turning left from the opposing approach, and lD5 – Install signal backplate/retroreflective backplates crashes involving pedestrians. Where to use - Signalized intersections with poor visibility of the intersection from driver unaware of intersection D1, D2, D5, D6 C2 B4 Keywords: right turn on red PED SIG approaches, a crash history or observed conflicts involving lack of awareness of the intersection or traffic control, and observed speeding on approaches to the nighttime conditions D1, D2, D5 intersection. right turning vehicles hit from side A3, C1, G5 B1, G4 lA4 – Employ signal coordination P Where to use - Signalized intersections with a high frequency of crashes involving Keywords: retroreflective, backplate High frequency of rear-end crashes major street left-turning and minor street right-turning vehicles where adequate safe attributed to: D6 – Install intersection warning devices gaps in opposing traffic are not available. Major road rear-end crashes associated with l left turning vehicles hit from behind A1 B1 B3 Where to use - Signalized intersections with poor visibility of the intersection from speed changes can also be reduced by re-timing signals to promote platooning. left opposing vehicles hit from behind B1 B3 Keywords: signal coordination, signal timing, cycles approaches, conflicts involving lack of awareness of the intersection or traffic control, PED and observed speeding on approaches to the intersection. Intersection warning right turning vehicles hit from behind A3 B1, B5 devices can include warning signs, beacons, and transverse rumble strips. lA5 – Employ emergency vehicle preemption standing water on roadway G1 Where to use - Signalized intersections where normal traffic operations impede Keywords: advance warning sign, positive guidance BIKE PED vehicles unable to stop safely (skidding) G2 emergency vehicles and where traffic conditions create a potential for conflicts D7 – Convert pole mounted to overhead signals between emergency and non-emergency vehicles. l driver unaware of intersection D1, D2, D5 D3, D4, D8 D7 Where to use - Signalized intersections with poor visibility of the intersection from approaches, a crash history or observed conflicts involving lack of awareness of nighttime conditions D1, D2, D5 D4 D7 A6 – Remove unwarranted signal l the intersection or traffic control, and observed speeding on approaches to the Where to use - Signalized intersections where the traffic volumes and safety record do speed differentials of vehicles A4, E3 intersection. not warrant a traffic signal. sudden stops A2, A3 A4, D3 Keywords: convert signal, pedestal mounted, mast arm Keywords: unwarranted, remove signal High frequency of left-turn crashes D8 – Install supplemental pole-mounted signal on near-side approach attributed to: A7 – Change green signal to flashing yellow arrow for permissive left turns l l Where to use - Signalized intersections with poor visibility of the intersection from left turn vehicles hit by opposing traffic A1, A3, A7, C1 B1, B4 B3 Where to use - Signalized intersections with high frequency of angle crashes involving approaches, a crash history or observed conflicts involving lack of awareness of left-turning and opposing through vehicles. The flashing yellow arrow (FYA) can be nighttime conditions D1, D2, D5 the intersection or traffic control, and observed speeding on approaches to the used in place of the simple circular green light and other signals to help convey the High frequency of sideswipe crashes intersection. attributed to: message that left-turning drivers need to yield to on-coming traffic. Keywords: add signal, signal head SIG Keywords: FYA, flashing yellow arrow, phasing, left turn, protected, permissive vehicles within intersection A1 B1 High frequency of pedestrian/bicycle lA8 – Install/implement pedestrian signal improvements crashes: Where to use - Signalized intersections with conflicts between vehicles and CATEGORY E: IMPROVE on school routes or near generators of ped/ A8 B2, E2 pedestrians crossing at the intersection, high volume of crossing pedestrians or DRIVER COMPLIANCE WITH bike traffic bicyclists, vehicles not yielding to pedestrians in crosswalk, and high pedestrian TRAFFIC CONTROL DEVICES vehicle/bicycle sideswipes on approaches A9, G1 delay due to few available gaps in traffic. Measures can include increasing pedestrian clearance intervals (or increasing the cycle length for pedestrian crossing), lE1 – Provide public information and with left turning vehicles A1, A3 A9 implementing leading pedestrian interval and installing pedestrian pushbuttons and education Address overall safety issues: pedestrian countdown signals. Where to use - Signalized intersections violation of traffic laws E1 A9, E2 Keywords: pedestrian, crossing, cycle length, signal phasing, pedestrian interval, countdown PED with a high frequency of crashes related to drivers either being unaware of (or refusing intersection near railroad crossing G3 to obey) traffic laws and regulations that impact traffic safety (especially red-light lA9 – Install bicycle signal intersection near fire station Where to use - Signalized intersections with conflicts between vehicles and bicycles running, speeding, and not yielding to pedestrians). BIKE PED A5 crossing at the intersection, high volume of bicyclists, vehicles not yielding to bicyclists. excessive delay A6 E2 – Provide targeted conventional enforcement of traffic laws l disobedience of traffic signal BIKE Where to use -Signalized intersections with a high frequency of crashes related to A6 A9, D3, D8 drivers either being unaware of (or refusing to obey) traffic laws and regulations that CATEGORY B: REDUCE impact traffic safety. BIKE PED SIG INTERSECTION CONFLICTS lE3 – Post reasonable, safe, and consistent speed limits on intersection THROUGH GEOMETRIC approaches IMPROVEMENTS Where to use - Signalized intersections with a high frequency of crashes attributed to Key to the Brochure drivers who intentionally disobey posted approach speed limits. B1 – Provide/improve turn lane l Keywords: Speed, speed management Costs: channelization Costs will also vary considerably and are affected by local conditions. Costs are ranked Where to use - Signalized intersections as: low, moderate, moderate to high, and high. The scale is meant to reflect costs with a high frequency of rear-end collisions relative to the other strategies described in the category (signalized or unsignalized). resulting
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