Media Relations Contact:
July 24, 2001
Information on DART Light Rail
DART's Rail Cars Are Electric-powered Wonders
As customers ride DART's electric-powered light rail vehicles, they are riding the wave of the future, and traveling into the past as well.
Like the streetcars of yesterday, the new non-polluting rail cars are powered by electricity fed from overhead lines. But each DART light rail vehicle is a state-of-the-art example of modern rail technology. A "catenary system" of two electrical cables provides stable working voltage for all trains on the 20-mile start-up track.
DART opened its light rail system in June 1996 with a fleet of 40 cars and has added 55 more cars to the fleet to improve service and to accommodate the expansion of the system to Garland, Richardson and Plano.
What makes it run?
DART's 20-mile light rail system requires about 2 million kilowatt hours per month from TXU to feed into the 14 mainline substations -- big gray boxes measuring 12 feet wide, 40 feet long and 14 feet high located at intervals of 1.5 to 1.75 miles along the line. Two more substations will provide power along the 3-mile line between Mockingbird and White Rock stations.
Inside the substations, more than 13 thousand volts of AC electrical power is converted into the 750 (per spec sheet below) volts of DC energy required to run the trains.
Two additional substations are located at DART's Service & Inspection Facility. The power distributed from each substation varies, depending on the number of trains in service and operating speed of rail traffic.
Not all substations have to be operational for the light rail system to work. Power can be shifted among the substations in the event of a power failure at one of the substations. Substation power flows into catenary lines hanging 20 feet above the tracks.
"Catenary" is actually a geometric term that refers to the curve of the heavy top cable that hangs in a scalloped design from pole to pole on hinged cantilevers that extend out to the middle of the tracks. Distances between poles vary between 50 feet on curves and hills to 210 feet on straight stretches of track. The shorter the curve or the steeper the hill, the closer together the poles must be to maintain proper alignment between the contact wire and the track.
The thinner contact wire is stretched taut between one and four feet below the curved catenary wire and is connected to the cable above by hangers placed 20 to 25 feet apart, again depending on the length of the span between poles. On the top of each rail car is a "pantograph" -- a bar 78 inches wide with a carbon insert for conducting electricity. The pantograph picks up power from the contact wire as it moves along the track, and feeds it into the four 175-horsepower electric motors that drive the train. Each light rail car weighs 107,000 pounds and carries 160 passengers.
DART Light Rail Technical Information
||Double-ended, articulated car, multiple unit operation up to four cars
||12 feet, 6 inches
||8 feet, 10 inches
||92 feet, 8 inches
||160 passengers, 76 seated
||Top speed: 65 miles per hour
||25-35 miles per hour
||1-3-car trains operating every 5 to 10 minutes in peak periods, and every 20-30 minutes off-peak
||Lightweight, welded steel, with reinforced fiberglass covering operator cab and weatherproof articulation (bending) section
Designed for 30-year life
||Constructed of stainless steel and lined with an upholstered, padded insert. Rubber interior flooring
||Heating, ventilation, and air-conditioning system
||Steel-tired with acoustic dampening
||Four sliding doorways per side
||Wheelchair-accessible with accommodations for four wheelchairs per vehicle
||750 Volts DC. Requires 20 KWH per hour of operation
||$2.5 million each (includes design, engineering, shipment, etc.).
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