Buffer stop

Summary

A Buffer stop, bumper, bumping post, bumper block or stopblock (US), is a device to prevent railway vehicles from going past the end of a physical section of track.

The design of the buffer stop is dependent, in part, on the kind of couplings that the railway uses, since the coupling gear is the first part of the vehicle that the buffer stop touches. The term "buffer stop" is of British origin, since railways in Great Britain principally use buffer-and-screw couplings between vehicles.

TypesEdit

Several different types of buffer stop have been developed. They differ depending on the type of coupler used and on the intended application.

  • Buffer stops with anticlimbers. These are particularly important for passenger railway applications, because the anticlimbers reduce the likelihood of telescoping of the railroad cars during a head-on impact.
  • Buffer stops for a knuckle coupler or an SA3 coupler (centrally positioned between the two rails)
  • Buffer stops with traditional "buffers" on either side
  • Hydraulic buffer stops
  • Friction buffer stops (bolted down to the rail)

If there is extra room behind the bumper block, there is usually a sand or ballast drag that is designed to further retard a runaway train. One such accident occurred when a Northern City Line train powered past the bumper block at Moorgate station in 1975 on the London Underground system.

Energy-absorbingEdit

Largely because of its mass, a train transfers an enormous amount of kinetic energy in a collision with a buffer stop. Rigid buffers can safely cope only with very low-speed impacts (i.e., nearly stationary). To improve stopping performance, a way of dissipating this energy is needed, through compression or friction. Following a buffer stop accident at Frankfurt am Main in 1902, the Rawie company developed a large range of energy-absorbing buffer stops. Similar hydraulic buffer stops were developed by Ransomes & Rapier in the UK.[citation needed]

ExamplesEdit

  • Raja Trains Depot in Tehran
    • Stopping speed: 20 km/h (12 mph)
    • Stopping distance: 20 m (66 ft).[1]

Wheel stopEdit

Wheel stops or car stops are used to stop small numbers of light vehicles at the end of level storage tracks or to chock individual railroad cars on shallow grades.[2][3][4][5][6]

GalleryEdit

Examples of accidentsEdit

 
The aftermath of the Gare Montparnasse accident
  • 22 October 1895 – Gare Montparnasse, Paris, France – An express train overran the buffer stop and fell into the street below.
  • 1902 – Frankfurt am Main, Germany – Serious buffer stop collision inspires development of Rawie range of energy-absorbing buffer stops.
  • 27 July 1903 – Glasgow, Scotland – A train arriving at the St Enoch terminal station failed to stop in time and collided heavily with the buffer stop, sustaining severe damage. Sixteen people were killed, 13 instantaneously and 3 at a later time due to injuries received. 64 people were injured, of which 17 required hospital treatment.
  • 28 February 1975 – Moorgate Underground rail crash – 43 killed, 74 injured – buffer stop collision made far worse by small size "tube" train running into large dimensioned dead-end tunnel beyond. The tunnel could accommodate full-size surface stock thus permitting the smaller train to concertina inside the tunnel.
  • 13 April 1978 – Budapest, Hungary – commuter train overruns a buffer stop owing to brake failure and crashes into the station building. 16 killed, 25 injured.[7]
  • 8 January 1991 – Cannon Street station rail crash, London – 2 killed, 200+ injured – commuter train hits buffer stops.
  • 22 February 2012 – Buenos Aires, Argentinaa commuter train collided with buffer stops at a train station in Buenos Aires during the morning rush hour. The accident killed 51 people and injured more than 700 in Argentina's worst rail accident in 30 years.[8] The buffer stops do not absorb energy.
  • 15 January 2013 – Saltsjöbaden, Sweden – A train parked with the train control lever at "Full throttle" was set in motion when a cleaner closed the door on a four-car EMU commuter train in Neglinge depot. It reached 80 km/h and demolished a buffer stop at Saltsjöbaden station before crashing into a small apartment block beyond the end of the track, badly injuring the cleaning lady.[9]
  • 20 March 2015 – Uttar Pradesh, India – The Dehradun-Varanasi Janata Express derailed near Bachhrawan, resulting in at least fifty-eight deaths and 150 people being injured. The driver reported by radio that the brakes on the train had failed, and that he could not stop the train. It was diverted into a siding and crashed through the buffers at Bachhrawan.[10]
  • 29 September 2016 – Hoboken, New Jersey – The cab car of a NJ Transit Pascack Valley Line commuter train entering Hoboken Terminal overran the buffer block on track five at 8:45 am. The train continued across the low-level passenger concourse connecting the platforms and slammed into a wall of the terminal building, causing serious structural damage. One person was killed and more than 100 were injured.
  • 13 March 2021 – Kirkby, United Kingdom – A Class 507 electric multiple unit operated by Merseyrail collided with the buffer stop. The only injury was the driver of the train. The cause was found to be that the driver was using a mobile phone whilst driving. The distraction led him to enter the station at excessive speed. He was fired and prosecuted, pleading guilty to a charge of endangering the safety of people on the railway.

See alsoEdit

ReferencesEdit

  1. ^ "Infrastructure (Iran)". Railway Gazette International. 1/2009: 16. January 2009.
  2. ^ "Aldon railcar wheel stops".
  3. ^ "Rails Company - Wheel Stops". Archived from the original on January 30, 2020.
  4. ^ "Wheel Stops - Track Components". kimessteel.com.
  5. ^ "Western Cullen Hayes Wheel and Car Stops".
  6. ^ "Car Stops – The Nolan Company". nolancompany.com. 4 February 2016.
  7. ^ "A Csepeli Hév fekete áprilisa – 33 éve történt a tragikus HÉV baleset". Retrieved 11 November 2012.
  8. ^ "Argentine train crash kills 49 people, hurts 600". Yahoo.com. 22 February 2012. Retrieved 22 February 2012.
  9. ^ "Stockholm train crashed into apartments 'by cleaner'". BBC News. January 15, 2013.
  10. ^ Mahesh, Niha. "32 Die as Train Derails Near Rae Bareli in Uttar Pradesh, 50 People Injured". NDTV India. Retrieved 20 March 2015.

External linksEdit

  • Book about Buffer Stops in Victoria