• Telescoping (Railcar going on top of another railcar)

  • Discussion related to DC area passenger rail services from Northern Virginia to Baltimore, MD. Includes Light Rail and Baltimore Subway.
Discussion related to DC area passenger rail services from Northern Virginia to Baltimore, MD. Includes Light Rail and Baltimore Subway.

Moderators: mtuandrew, therock, Robert Paniagua

  by rail10
 
What causes the metrorail cars to telescope from time to time as in the last accident.Also is telescoping hazard possible on the Nyc,Boston,Bart subway cars and etc as well?
  by farecard
 
rail10 wrote:What causes the metrorail cars to telescope from time to time as in the last accident.?

F=ma. Or you can say 0.5mv^2...

Cars telescope when asked to absorb the massive amounts of energy in a rail collision. If the frames are strong enough, that won't happen, but the energy has to go somewhere, either an inelastic collision or into heat. [Virtually all mechanical entropy ends up as heat...].
  by Sand Box John
 
"rail10"
What causes the metrorail cars to telescope from time to time as in the last accident.


WMATA's 1k and I believe 2, 3 and 4k cars were not designed to withstand at speed collision impact. The cars do not have center sill beam that connect the truck bolsters and anticlimbers to each other. The car bodies are an interracial part of the cars structure. Conventional railroad passenger cars are a body on a frame. Conventional railroad passenger cars are designed to withstand at speed collision impact. They have full length center sill beams, the car ends are braced to car frame center sill beam.

See page 17 NTSB Woodley Park-Zoo Wreck Report for 1k car body diagram. (2.90 MB PDF file)

Also is telescoping hazard possible on the Nyc,Boston, Bart subway cars and etc as well?

Can't speak for the various generations of New York and Boston rolling stock, but I would hazard a guess the are far more crash worthy then WMATA's cars. The bart rolling stock that was built by the Rohr Corporation are basically structurally identical to the cars they built for WMATA.