Third Rail Safety

Discussion in 'Off Topic' started by Jon from Rhode Island, Sep 4, 2021.

  1. Jon from Rhode Island

    Jon from Rhode Island Well-Known Member

    Joined:
    Aug 20, 2021
    Messages:
    224
    Likes Received:
    299
    I have always been intrigued by third-rail power systems because of the inherent hazard of having a live current at ground level. Then I saw this picture from last week and it blew my mind: https://www.instagram.com/p/CTUtwaen5oX/
    Can anyone explain to this non-physicist how a train can operate in these conditions without frying everyone inside? And how does a rail operator mitigate the risk associated with third rail in outdoor settings where fencing may be inadequate or nonexistent?
     
  2. CK95

    CK95 Well-Known Member

    Joined:
    Apr 13, 2019
    Messages:
    3,177
    Likes Received:
    9,162
    So the collector shoe on the train (the part that is in contact with the third rail) is isolated from the carriages themselves.

    As for on track safety we have section/breather gaps that we can step through, we also have rail guards that are basically large plastic moulds which slot over the third rail, thus eliminating the risk of contact, if possible though we just isolate the area that is being worked in as this is obviously the safest option.

    When you’re talking about pooling water in contact with a current though it’s basically a case of don’t step in the water (obviously).

    In terms of public access to the third rail, it’s basically common sense to not touch it, but it is an inherently unsafe piece of infrastructure which is very much outdated now, you do see sections of third rail which are painted red or yellow but usually it’s a sign posted warning.
     
    Last edited: Sep 4, 2021
    • Like Like x 2
  3. Coastway trainspotter

    Coastway trainspotter Well-Known Member

    Joined:
    Jan 12, 2021
    Messages:
    2,852
    Likes Received:
    2,187
    I am more of a fan of overhead live wires , I wish English railways used them instead of the 3rd rail , like most European railways
     
  4. CK95

    CK95 Well-Known Member

    Joined:
    Apr 13, 2019
    Messages:
    3,177
    Likes Received:
    9,162
    we do?
     
    • Like Like x 2
  5. Coastway trainspotter

    Coastway trainspotter Well-Known Member

    Joined:
    Jan 12, 2021
    Messages:
    2,852
    Likes Received:
    2,187
    No , most English railways use third rail
     
  6. CK95

    CK95 Well-Known Member

    Joined:
    Apr 13, 2019
    Messages:
    3,177
    Likes Received:
    9,162
    Almost half of the network is energised by overhead wires, where as only around a third is energised with third rail electrification.
     
    • Like Like x 4
  7. Coastway trainspotter

    Coastway trainspotter Well-Known Member

    Joined:
    Jan 12, 2021
    Messages:
    2,852
    Likes Received:
    2,187
    Alright …

    My local is third rail , I thought most of the network is
     
  8. JealousSheep768

    JealousSheep768 Well-Known Member

    Joined:
    Aug 6, 2021
    Messages:
    371
    Likes Received:
    533
    Anywhere outside of 5he south/ southeast is usually overhead. Commuter rail tends to be 3rf rail in the UK for London
     
    • Like Like x 1
  9. Richard CZE

    Richard CZE Well-Known Member

    Joined:
    Aug 20, 2020
    Messages:
    544
    Likes Received:
    584
    The third rail is not protected by a cover. Prague Metro trains draw power from the bottom of the power line. Dangerous for animals crossing the tracks.

    images (1).jpeg
     

    Attached Files:

  10. Calidore266

    Calidore266 Well-Known Member

    Joined:
    Jun 17, 2021
    Messages:
    1,198
    Likes Received:
    1,721
    Here in Chicago, two north suburban CTA lines used to have overhead wires, but those were eventually replaced with third rails for reliability reasons (The Evanston line in 1973 and the Skokie one in 2004). Several CTA train lines run at street level for part of their length, and yes, we're taught from birth that third rail contact = death.
     
  11. driverwoods#1787

    driverwoods#1787 Well-Known Member

    Joined:
    Feb 21, 2021
    Messages:
    9,087
    Likes Received:
    5,608
    In the United States that is also found on Metro-North Hudson Harlem New Haven lines Pelham to Wakefield section 750v DC Bottom Contact Philadelphia Market Frankford elevated line. This design can be deadly in Railway crossing accident just look at 2015 Valhalla railroad crossing. LIRR top contact 750v DC
     
  12. fabdiva

    fabdiva Well-Known Member

    Joined:
    Jan 13, 2019
    Messages:
    906
    Likes Received:
    809
    Most of the DC 3rd Rail network was built out in the 20s and 30s by the Southern Railway - generally anything electrified since the 60s has been 25kV AC overhead wires, unless an extension of the 3rd rail system where compatibility was preferred. I understand that now with AC traction packs making dual voltage stock easy to build any future electrification in the SE will likely be 25KV AC overhead.
     
  13. Jonne1184

    Jonne1184 Well-Known Member

    Joined:
    Aug 11, 2021
    Messages:
    213
    Likes Received:
    286
    I dont really get the connection between 3rd rail safety and the video. In the case of the video in the original post, overhead wires would have certainly shorted out, although probably even so without a train running beneath them, while as you can see the 3rd rail did not. AFAIK they are covered in NY anyway.

    And for frying everyone inside? How so? The metal body has a far lower resistance as the air and passengers inside it anyway.
     
  14. Richard CZE

    Richard CZE Well-Known Member

    Joined:
    Aug 20, 2020
    Messages:
    544
    Likes Received:
    584
    The third power track used in England can be dangerous, especially for animals around the railway line. I wonder why it doesn't have a protective cover.
     
  15. JJTimothy

    JJTimothy Well-Known Member

    Joined:
    May 14, 2018
    Messages:
    1,528
    Likes Received:
    975
    The short-lived Southern Region Class 71 electric loco' ran third rail most of the time but had a pantograph. At yards where staff would be walking around a lightweight overhead supply suitable only for low speed use was erected precisely because of this concern.
     
  16. Jonne1184

    Jonne1184 Well-Known Member

    Joined:
    Aug 11, 2021
    Messages:
    213
    Likes Received:
    286
    I would hazard a guess that this is due to the original design not having a cover and thus the rail being to near to the running rails. You would need a side mounted collector shoe for that to work and looking at how close the shoe is to the side of the wheels, there is probably no other way than having a top mounted hinge for it.
     

Share This Page