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9 COMMON LIGHT RAIL VEHICLEMOTOR VEHICLE · Motorists make illegal left turns against static no left- COLLISION SCENARIOS turn signs (at locations where turns are prohibited) and collide with LRVs approaching from behind. Considering the many different types of street-running oper- · Motorists violate active turn-prohibition signs and train- ations of LRT, there are many different scenarios of possible approaching warning signs in conflict with LRV opera- collisions between LRVs and motor vehicles at signalized tion (at locations where turns are permitted/prohibited). intersections. However, the most common types of collisions · Motorists make left turns from adjacent through-only are motor vehicles making illegal or improper left turns in lanes instead of from the lanes shared with the LRVs front of LRVs and right-angle collisions with vehicles on the (mixed-use). cross streets; therefore, they are the focus of this synthesis. · Drivers encroach on or stop on the tracks and are struck by an LRV (coming from either direction) at a right angle Based on a review of the most recent literature and inter- (side-running alignment only). views with selected transit agencies for this research, the · Drivers run a red signal indication and collide with an most common scenarios of left-turn and right-angle colli- LRV (coming from either direction) at a right angle. sions at signalized intersections can be categorized as the following: Table 2 presents each of these six collision scenarios along with a list of possible causes of each scenario. The following · Motorists in left-turn pocket lanes violate the red left- section presents a number of countermeasures that can be turn signal indication and collide with LRVs approach- implemented to mitigate the occurrence of these collision ing from behind. scenarios.
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10 TABLE 2 COMMON COLLISION SCENARIOS AND POSSIBLE CAUSES Collision Scenario Possible Causes Signs do not convey to motorists why they are not allowed to turn. Motorists initiate their left turns against the signal as soon as the cross-street traffic receives the red (particularly common at locations with leading left-turn phases). Motorists in the left-turn lane mistake the through-traffic signals for those controlling Motorists in left-turn pocket lane the left-turn movement. violate the red left-turn signal Motorists in the left-turn lane cue off of the movement of the through vehicles. indication and collide with LRVs approaching from behind. Motorists make left turns across the LRT right-of-way immediately after termination of their green left-turn arrow. Motorists confuse LRT signals with traffic signals. Where traffic signals are pre-empted during the left-turn phase, motorists may incorrectly assume that the signal failed and violate the signal. There may be too few locations to make left turns across the tracks leading to increased pressure to turn left where such movements can be made, even if prohibited. Left turns were previously allowed before the LRT system was constructed. Permanently prohibiting a traffic movement that was previously allowed disrupts normal, expected travel patterns. Motorists make illegal left turns Motorists who are used to violating regulatory signs with little consequence at against static no left-turn signs conventional signalized intersections need to better understand the risks of violating and collide with LRVs turn prohibitions at intersections with LRT. approaching from behind. There are too many signs at intersections. Multiple signs increase driver information processing time and increase the potential for missing important information. Traffic control devices place an emphasis on prohibited rather than permitted movements. Drivers may be confused about where they can make turn movements and where a through movement is the only permitted movement. Signs may be activated too far in advance of the LRV arrival. If motorists perceive that the LRVs do not come even when the signs are active, they may lose respect for the Motorists violate active turn- signs and turn in conflict with an LRV. prohibition signs and train- approaching warning signs in Signs may be activated too late to provide sufficient advance warning to motorists. conflict with LRV operation. Motorists do not understand why the signs are on and/or why turns are prohibited. Permitting movements at some times and prohibiting them at others causes driver confusion. Motorists make left turns from Drivers are confused about which lane to turn from. Failure to understand the proper through lanes instead of adjacent behavior at these locations may lead to vehicletrain conflicts. or lanes shared with the LRVs. Having too many transverse markings on the roadway in the vicinity of the intersection (e.g., crosswalk, stop line, railroad markings) can cause confusion about where to stop. Drivers encroach on or stop on the tracks and are struck by an Motorists may not perceive the LRT tracks crossing the roadway on the approach to the LRV (coming from either intersection. direction) at a right angle. Motorists attempt right or left turns on red and stop on the tracks to wait for a gap in traffic as the LRV approaches. Drivers run a red signal indication and collide with an Motorists are unaware an LRV is coming or speed through the intersection in an LRV (coming from either attempt to beat an approaching LRV. direction) at a right angle.