Click for next page ( 24


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 23
23 CHAPTER FOUR CASE STUDIES This chapter presents, through case studies, detailed informa- median strips. Although a quantitative study was not per- tion about the operating environment, collision history, and formed, the results were not as effective as was originally countermeasures tested and/or implemented for mitigating hoped. Desiring to find a solution to the problem, TriMet collisions between LRVs and motor vehicles at signalized tested the use and effectiveness of LRV-activated train- intersections at a variety of transit agencies. The case studies approaching warning signs, which have gone through several are based on a review of the recent relevant literature and struc- generations since its introduction a few years ago. The signs tured telephone interviews with selected transit agencies. first started with the word "Train," which flashed when a train approached the intersection. Next they used a flashing sign dis- playing the words, "Train Coming." Now they use a sign with TRI-COUNTY METROPOLITAN TRANSPORTATION an icon of an LRV with the word "Warning." The orientation DISTRICT OF OREGON--MAX LIGHT RAIL of the LRV icon depends on the direction of the train with TriMet began operation of their 15-mile Eastside MAX Blue regard to the motorists. For left-turning motorists, the icon is light rail line in September 1986, which was among the first the front of an LRV to indicate that the train is approaching light rail systems in the nation. Since then, they have expanded from the same direction; the icon for the cross-street traffic is tracks by adding 18 miles in 1998, 5.5 miles in 2001, and the side or profile of an LRV to indicate that it is approaching 5.8 miles in 2004 for a total of 44 miles. at a 90-degree angle. According to TriMet, the LRV-activated train-approaching warning signs have been effective at reduc- ing left-turn collisions. As an example of their effectiveness Collision History in Portland, in 2004 when TriMet opened the Interstate MAX Yellow Line that crosses through many signalized intersections, When TriMet designed the system, they assumed it would they established criteria for putting in the LRV-activated operate like a street car system; however, they realized their train-approaching warning signs. The criteria included factors design of the train into the streets was different than that of a such as speed, volume, school zones, crossing geometry, and street car system. The assumption was that the "little red ball" sight lines. TriMet got the city of Portland to join in the effort on the traffic signal would sufficiently deter motorists from and to use the signs liberally. As a result, they have experi- making maneuvers in conflict with LRT operations, but that enced very few left-turn collisions since opening the MAX assumption was incorrect. They found that left-turn drivers in Yellow Line. particular seemed to lose attention on the traffic signal con- trolling the left-turn movement and instead seemed to be The city of Portland has accepted the use of the LRV- responding to other cues like the pedestrian signals and the activated train-approaching warning for left turns as standard traffic signals controlling the parallel through movement. practice; however, the city has not installed many of these signs Early on in their operations they had problems with left-turn for the cross-street traffic. This could in part explain the shift collisions, and therefore, have made improvements that have from a majority of left-turn collisions initially to the 5050 split helped control the left-turn collisions to some extent. Over the between left-turn collisions and right-angle collisions. past 6 to 7 years they have experienced about a 5050 split between left-turn collisions and right-angle collisions caused Other effective countermeasures that TriMet has imple- by motorists running red lights on the cross-street approaches. mented to mitigate collisions between LRVs and motor vehi- cles at signalized intersections include Countermeasures All-red phase. Washington County implemented an all- TriMet does not necessarily believe that all of the motorists red phase that holds all traffic approaches in a stopped violating the traffic signals are doing so deliberately, but sim- position while the train passes through the intersection. ply not paying as much attention as needed at intersections. Lower train speed. Along the Interstate Max Yellow Line, TriMet's goal has been to capture motorists' attention. To do TriMet initially started operations with a train speed of so, TriMet's response to the left-turn problem was to duplicate 30 mph as opposed to 35 mph. Although they originally the left-turn traffic signals at select locations. Left-turn traffic had plans to raise the speed to 35 mph, they have not yet signals were placed on the far side of the intersection within seen a reason to do so. The city of Portland followed