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?
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it’s basically common sense to not touch it, but it is an inherently unsafe piece of infrastructure which is very much outdated now, you do see sections of third rail which are painted red or yellow but usually it’s a sign posted warning.
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
Almost half of the network is energised by overhead wires, where as only around a third is energised with third rail electrification.
Anywhere outside of 5he south/ southeast is usually overhead. Commuter rail tends to be 3rf rail in the UK for London
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.
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.
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
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.
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.
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.
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.
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.