Light Rail Vehicle Collisions with Vehicles at Signalized Intersections

11CHAPTER THREECOUNTERMEASURES TO MITIGATE COLLISIONS BETWEEN LIGHT RAILVEHICLES AND MOTOR VEHICLES AT SIGNALIZED INTERSECTIONSThis chapter focuses on the countermeasures used to mitigatecollisions between LRVs and motor vehicles at signalizedintersections. According to Coifman and Bertini (3), a countermeasurefor mitigating collisions between LRVs and motorvehicles should address motorists’ expectations at conventionalintersections as well as work to keep motorists within the lawat LRT crossings. They go on to state,A successful collision countermeasure should accomplish atleast one of the following goals:Remind the driver that there are special risks in the givensituationPhysically prevent the driver from taking these additionalrisks (3, p. 4).Table 3 shows a variety of countermeasures, found in areview of the literature and through interviews with selectedtransit agencies, which have been tested, implemented, orsuggested to mitigate collisions between LRVs and motorvehicles at signalized intersections. The sections that followprovide details on each of these countermeasures.PHYSICAL BARRIERSPhysical barriers provide physical separation between movements.Transit agencies have employed a variety of physicalbarriers, including gates, bollards, and delineators to providephysical separation between LRV and motor vehicle movements.These countermeasures are discussed here.GatesAn FTA-sponsored study was undertaken in 2002 to investigatethe use of railroad crossing gates to reduce collisionsbetween LRVs and motor vehicles at intersections wherestreets run parallel to LRT and motorists are permitted to makeleft turns across the tracks (8). The two types of gates includedin the study were:• Left-turn gates, which can be used to physically prohibitmotorists from turning left in conflict with an LRV. Leftturngates can be installed parallel to the tracks (along theline separating the left-turn lane from the tracks in amedian-running environment) or at 90 degrees to the leftturnlane directly in front of the first left-turn vehiclewaiting to turn. Calgary Transit has installed both typesof left-turn gates.• Four-quadrant gates—From the review of a variety ofgates conducted in the FTA study, full-closure, fourquadrantcrossing gates were selected as the best option asthey offered a number of advantages over the other gatesystems reviewed. A full-closure, four-quadrant crossinggate system was installed in October 1998 at the124th Street intersection in south central Los Angeles todeter motorists from making left turns around loweredrailroad crossing gates. During the experimental phase,data recorded for the first 6 months of operation at the124th Street intersection showed that the four-quadrantgate approach resulted in a 94% reduction in the numberof risky moves by motorists using the intersection. Theuse of four-quadrant gates has continued in Los Angelesand they have continued to have success with this countermeasure.Four-quadrant gates are effective in semiexclusiverights-of-way, but not for street operations.Knock-Down BollardsCoifman and Bertini (3) note that at a typical median LRTcrossing with left-turn pocket lanes, the left-turn lanes areoften separated from the trackway by a narrow curb, whichmay end before the intersection to allow for installation of andpassage for a pedestrian crosswalk. With the end of this curbat the crosswalk, motorists frequently enter the LRV dynamicenvelope during their left turns. The problem is compoundedwhen drivers cross the stop bar and stop at the near side of thecrosswalk. In these situations, knock-down bollards can providea safe and effective means for restricting automobilemovements in the crosswalk, effectively reducing the length ofthe potential LRV–motor vehicle collision zone.Raised Medians or DelineatorsIn side-running, semi-exclusive alignments, raised medians ordelineators can be installed to deter left-turn motorists fromdriving around lowered automatic gates during their turns. Inthis application, the raised medians or delineators are installedon the cross street, perpendicular to the tracks, between thetrackway and the intersection.