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 11
11
CHAPTER THREE
COUNTERMEASURES TO MITIGATE COLLISIONS BETWEEN LIGHT RAIL
VEHICLES AND MOTOR VEHICLES AT SIGNALIZED INTERSECTIONS
This chapter focuses on the countermeasures used to mitigate turn lane directly in front of the first left-turn vehicle
collisions between LRVs and motor vehicles at signalized waiting to turn. Calgary Transit has installed both types
intersections. According to Coifman and Bertini (3), a counter- of left-turn gates.
measure for mitigating collisions between LRVs and motor · Four-quadrant gates--From the review of a variety of
vehicles should address motorists' expectations at conventional gates conducted in the FTA study, full-closure, four-
intersections as well as work to keep motorists within the law quadrant crossing gates were selected as the best option as
at LRT crossings. They go on to state, they offered a number of advantages over the other gate
systems reviewed. A full-closure, four-quadrant cross-
A successful collision countermeasure should accomplish at ing gate system was installed in October 1998 at the
least one of the following goals: 124th Street intersection in south central Los Angeles to
deter motorists from making left turns around lowered
Remind the driver that there are special risks in the given
situation railroad crossing gates. During the experimental phase,
Physically prevent the driver from taking these additional data recorded for the first 6 months of operation at the
risks (3, p. 4). 124th Street intersection showed that the four-quadrant
gate approach resulted in a 94% reduction in the number
Table 3 shows a variety of countermeasures, found in a of risky moves by motorists using the intersection. The
review of the literature and through interviews with selected use of four-quadrant gates has continued in Los Angeles
transit agencies, which have been tested, implemented, or and they have continued to have success with this counter-
suggested to mitigate collisions between LRVs and motor measure. Four-quadrant gates are effective in semi-
vehicles at signalized intersections. The sections that follow exclusive rights-of-way, but not for street operations.
provide details on each of these countermeasures.
Knock-Down Bollards
PHYSICAL BARRIERS
Coifman and Bertini (3) note that at a typical median LRT
Physical barriers provide physical separation between move- crossing with left-turn pocket lanes, the left-turn lanes are
ments. Transit agencies have employed a variety of physical often separated from the trackway by a narrow curb, which
barriers, including gates, bollards, and delineators to provide may end before the intersection to allow for installation of and
physical separation between LRV and motor vehicle move- passage for a pedestrian crosswalk. With the end of this curb
ments. These countermeasures are discussed here. at the crosswalk, motorists frequently enter the LRV dynamic
envelope during their left turns. The problem is compounded
when drivers cross the stop bar and stop at the near side of the
Gates crosswalk. In these situations, knock-down bollards can pro-
vide a safe and effective means for restricting automobile
An FTA-sponsored study was undertaken in 2002 to investi- movements in the crosswalk, effectively reducing the length of
gate the use of railroad crossing gates to reduce collisions the potential LRVmotor vehicle collision zone.
between LRVs and motor vehicles at intersections where
streets run parallel to LRT and motorists are permitted to make
left turns across the tracks (8). The two types of gates included Raised Medians or Delineators
in the study were:
In side-running, semi-exclusive alignments, raised medians or
· Left-turn gates, which can be used to physically prohibit delineators can be installed to deter left-turn motorists from
motorists from turning left in conflict with an LRV. Left- driving around lowered automatic gates during their turns. In
turn gates can be installed parallel to the tracks (along the this application, the raised medians or delineators are installed
line separating the left-turn lane from the tracks in a on the cross street, perpendicular to the tracks, between the
median-running environment) or at 90 degrees to the left- trackway and the intersection.
OCR for page 12
12
TABLE 3
COUNTERMEASURES USED BY TRANSIT AGENCIES TO MITIGATE COLLISIONS BETWEEN
LRVS AND MOTOR VEHICLES AT SIGNALIZED INTERSECTIONS
Category Countermeasure1 Agency Example(s)2
Physical Barriers Gates (left-turn gates, four-quadrant gates) Calgary Transit, LACMTA
Knock-down bollards DART
Raised medians/delineators TriMet, DART, NFTA
(Buffalo)
Retractable delineators/barriers Michigan DOT
Traffic Signs Active train-approaching warning signs TriMet, DART, LACMTA
Active turn-prohibition signs Houston METRO, TriMet
Overhead lane-use control signs LACMTA
Use and placement of static signs Sacramento RT, TriMet
2nd train coming warning sign Maryland MTA
Signal Displays Red left-turn arrows Denver RTD, TriMet
Green arrow aspects for through traffic New Jersey Transit, TriMet
In-roadway lights Houston METRO
Programmable visibility signal heads TriMet
LRT signals with format and color different from traffic LACTMTA, Santa Clara
signals VTA
Far-side LRV signals TriMet
Traffic Signal All-red traffic signal phase LACMTA
Phasing Lagging left turns LACMTA, TriMet
LRV ìq ueue jump" or "head start" Utah
Signal pre-emption phasing TriMet
Pavement Contrasting pavement treatments Houston METRO
Markings/Treatments Crosshatch pavement markings New Jersey Transit
Lane-use markings (arrows) San Francisco MUNI
Extending/repositioning pavement treatments/markings Denver RTD
Public Public outreach materials LACMTA, Denver RTD
Outreach/Education State driver's license handbooks California
Enforcement Police presence LACMTA, Houston
METRO
Photo enforcement LACMTA
Other Lower train speeds TriMet
Sacramento RT, Houston
Train-mounted cameras
METRO
New Jersey Transit, San
LRV operator defensive driving Diego Metropolitan Transit
System
1
These countermeasures may not be applicable in all situations, such as emergency or reverse-running operations.
2
The agencies noted are just a few examples of those using the countermeasures. Therefore, the use of the
countermeasures is not necessarily limited to the agencies listed here.
Retractable Delineators or Barriers available at that time could not be used for the left-turn barrier
application as they would not be able to perform the number of
Retractable delineators can be installed to block unwanted daily "up and down" cycles required (more than 200/day) at
vehicular movements in a number of applications and could be the crossing (8).
particularly useful where there is insufficient space for the
installation of gates. The Los Angeles Department of Trans- Several other agencies have explored retractable delin-
portation (DOT) has investigated the use of retractable delin- eators or barriers since that time. METRO in Houston is
eators to block traffic making left turns across the Long Beach currently testing another type of retractable delineator for
Blue Line tracks at certain signalized intersections. Discus- use in keeping motorists out of the shared LRVleft-turn
sions between the Los Angeles DOT and a supplier in the early lane when trains are approaching. The Michigan DOT,
2000s concluded that the particular retractable delineators FRA, and Norfolk Southern Railway, in cooperation with
