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TCRP Web-Only Document 53 18 CHAPTER 3: ASSESSMENT OF THE OPERATIONAL AND SAFETY ASPECTS OF EXISTING, ALTERNATIVE, AND POSSIBLE SUPPLEMENTAL TRAFFIC CONTROL DEVICES The next step in the project was to analyze the operational and safety aspects of existing traffic control devices, as well as alternative and possible supplemental traffic control devices that could be used at the intersections identified for study, namely: North First Street and Brokaw Rd.; North First Street and Charcot Ave.; and North First Street and Trimble Rd. The general approach to this analysis was to gather and analyze a variety of data that would indicate how well the intersections currently operate and the existing level of safety at the intersections.
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TCRP Web-Only Document 53 19 Historical Crash Data The research team gathered crash data from both the City of San Jose and the VTA. Both data sets represented 3 years worth of crashes.
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TCRP Web-Only Document 53 20 time of day, weather conditions, lighting conditions, and surface conditions at the three intersections. The following discussion summarizes the issues identified as being most relevant to this project: Intersection of North First Street and Brokaw Rd. -- During the 3-year period, there were 64 reported crashes at this intersection, by far the highest crash rate of the three study intersections; however, there were no fatalities, and only 23 percent of the crashes resulted in injuries.
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TCRP Web-Only Document 53 21 For this project, it is important to characterize and assess the LRV-related crashes at the three study intersections. Table 10 characterizes the six LRV-related crashes, as reported by the City of San Jose Department of Streets and Traffic.
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TCRP Web-Only Document 53 22 Table 11. Summary of Crashes Involving LRVs within VTA Right-of-Way Intersection of North First St.
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TCRP Web-Only Document 53 23 Table 12. Summary of Reported Light Rail Near Miss Incidents (5/22/06 to 4/21/2009)
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TCRP Web-Only Document 53 24 potential high-risk incident with regard to the LRT. Red-light running on the cross-street was also not something predominate in the near-miss data.
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TCRP Web-Only Document 53 25 Figure 8. North First Street at Charcot Avenue Figure 9.
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TCRP Web-Only Document 53 26 A group of five technicians was trained off-site and in the field as camera operators and observers before the actual field data collection commenced. Training included operating the video equipment; positioning the cameras and video settings to maximize the coverage areas, conflict events, and risky behavior maneuvers that should be identified; making notes of the implications of any of these conflicts or risky behaviors, if any; and manual recording of any special events such as crashes and conflicts that could not be seen within the camera view or that could bias the risky behavior observations.
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TCRP Web-Only Document 53 27 determined set of risky behaviors. In order to clarify risky driver behavior patterns, the following were developed to categorize relevant risky behavior characteristics: Group 1: Left-Turn and Cross-Street Movements; Group 2: Right-of-Way (ROW)
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TCRP Web-Only Document 53 28 RISKY BEHAVIOR OBSERVATION DESCRIPTION OF BEHAVIOR Mainline left-turn vehicles queued on tracks ....... Left turn motorist from North First St.
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TCRP Web-Only Document 53 29 Table 14. Summary of Risky Behavior Observations RISKY BEHAVIOR OBSERVATION Number of Risky Behavior Observations North First St.
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TCRP Web-Only Document 53 30 The most observed risky behavior associated with a light rail maneuver was a left-turn during the yellow change and all-red clearance intervals, and in several cases completing the turn while the red interval was expiring. This behavior occurred consistently at all three intersections.
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TCRP Web-Only Document 53 31 The focus groups were designed around three different scenarios in which motor vehicles interfaced with LRT at signalized intersections. The three scenarios included: No Left Turn Allowed Scenario (parallel to the LRT line)
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TCRP Web-Only Document 53 32 different scenes. In each scene, a left turn was allowed at the intersection, and an active blankout warning sign was provided to indicate to the driver if a train was approaching.
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TCRP Web-Only Document 53 33 as shown in Figure 12 -- and two different active devices were used -- the W10-7 sign (shown in the top picture of Figure 13) and in-pavement lights (shown in the bottom picture of Figure 13)
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TCRP Web-Only Document 53 34 Figure 13. Cross-Street Scenarios with Various Traffic Signal Displays and Two Different Types of Active Traffic Control Devices (W10-7 Sign and In-pavement Lights)
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TCRP Web-Only Document 53 35 turn left, or go straight. A response sheet was provided for the participants on which to record their answers for each of the 27 scenes.
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TCRP Web-Only Document 53 36 most common response. One explanation could be that the participants were not familiar with this particular scenario and were confused about the relation between these scenes and the arrival of the trains.
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TCRP Web-Only Document 53 37 Table 16. Comparisons: No Left Turn Allowed Scenario # Traffic Signal Displays Comparison Traffic Control Devices for Scenario A Traffic Control Devices for Scenario B Which scenario is BETTER at conveying what the driver SHOULD do?
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TCRP Web-Only Document 53 38 Table 17. Comprehension: Left Turn Allowed Scenario Scene Numbers What SHOULD the driver do?
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TCRP Web-Only Document 53 39 Table 18. Comparisons: Left Turn Allowed Scenario # Traffic Signal Displays Comparison Traffic Control Devices for Scenario A Traffic Control Devices for Scenario B Which scene is BETTER at conveying what the driver SHOULD do?
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TCRP Web-Only Document 53 40 For the Cross-Street Scenario, the results of the comprehension activity are shown in Table 19. In all of the eight scenes, the through signals were red and the correct driver action was to stop; however, different left-turn displays and various active warning devices were used to indicate to participants whether or not a train was approaching the intersection.
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TCRP Web-Only Document 53 41 Table 20. Comparisons of Different Intersection Treatments: Cross-Streets # Situation Comparison Traffic Control Devices for Scenario A Traffic Control Devices for Scenario B Which scene is BETTER at conveying what the driver SHOULD do?
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TCRP Web-Only Document 53 42 near-miss incident data and observations of operations specifically, driver behaviors at the intersections. The team also assessed the operational and safety aspects of alternative and possible supplemental traffic control devices that might be used at the intersections to improve driver situational awareness and safety in general and under increased LRV speed conditions.
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TCRP Web-Only Document 53 43 about what to do)
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TCRP Web-Only Document 53 44 However, while the crash and observational data may not necessarily warrant treatment on the cross-streets in San Jose, the research team would recommend that in some locations, the installation of W10-7 signs on the cross-street approaches would be a prudent countermeasure if train speeds were to be increased to 40 mph. The primary reason for this recommendation is to provide an active warning to drivers on the cross-street regarding the arrival of an LRV.
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TCRP Web-Only Document 53 45 major street. All gates require signal communications and gate assembly equipment.
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