The Regional Transportation District plans installation of a system to detect intrusions by the end of the year along the Southwest Corridor Light …
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The Regional Transportation District plans installation of a
system to detect intrusions by the end of the year along the
Southwest Corridor Light Rail tracks as a safety measure because
the light rail tracks are very close to the freight rail
Freight train derailments disrupted light rail service in 2007
and again in January. The concern about the possibility of light
rail trains crashing into debris caused by a freight train
derailment prompted the effort to identify and install an intrusion
warning system to keep RTD passengers safe.
Pranaya Shrestha, RTD systems engineering manager, said RTD
evaluated several technologies and prefer a system of seismic
detectors. The detectors are programmed to pickup ground vibrations
caused by a freight train derailment and send out warning signals
to trains along the corridor.
He said RTD representatives and the consultant will do a “walk
through” this month of the stretch of track from Evans to the
end-of-the-line station at Mineral Avenue to evaluate the scope of
the project. The data collected from the evaluation will help RTD
engineering division prepare the specifications for the system. RTD
will then ask the contractor for a bid and, if the project can be
funded, the goal is to award the contract by the end of May and
have the system installed by the end of the year.
Shrestha said the system plans proposes installing a seismic
detector in each signal equipment vault along the stretch of track
from Evans to Mineral. Each vault is reached through a manhole and
the manholes are 500 feet apart. The seismic sensors will be
adjusted to filter out the normal vibrations caused by passage of a
freight train and light rail train. However, if the sensor picks up
vibrations strong enough to be a freight trail derailment, it would
send a signal to all the lights down the track, switching them to
red. The engineer said the signal also would pass to the trains and
shut off the power to those along that stretch of the track.
Early detection of a derailment is critical because, light rail
trains south of Littleton hit speeds as high as 55 miles an hour
and, at that speed, it takes about 600 feet to bring it to a stop
with emergency braking.
Shrestha said he is not aware of any other light rail system
using the seismic warning system but it is widely used along
freight rail tracks.
The light rail tracks from Evans to Mineral are the only
candidates for the intrusion sensing system. The freight train
tracks run parallel to the light rail tracks from California to
Union Station but the tracks are quite a bit further apart and the
light rail trains move slower, about 25 miles an hour, the engineer
Shrestha said the engineers have no idea what it will cost to
install and hook up about 50 seismic detectors, However, he said
RTD is receiving $5 million from the federal stimulus package and
that money is tentatively earmarked for the sensor project.
RTD evaluated several possible technologies including an
electric warning fence along the edge of the track, a motion
detector system using microwave transmissions and the seismic
The electric warning fence, along rail tracks in the mountains
to detect rock slides, was ruled out because of the possibility of
vandalism and the space it would take up. The microwave system was
deemed to be susceptible to false detection such as snow or hail
triggered the system so it was ruled out. The result is RTD now
proposes using the seismic detector system,
The decision to install the intrusion detection system came as a
result of the two freight train derailments in two years, in 2007
south of Arapahoe Community College and last year adjacent to the
downtown Littleton station.
Shrestha said RTD looked as several possible systems,
The tracks from Evans south to the Mineral Station are on a
narrow right-of-way. The result is the freight train tracks are
close to the light rail tracks. In some cases, the light rail and
freight rail tracks are only 16 feet apart.
In 2007 when the coal train derailed and several cars dumped
their contents on the light rail tracks, the northbound light rain
train hit the coal on the track and, while several cars were
derailed, no one was injured.
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