Future of Third Rail

[Ken H]

Indeed. This is a very pertinent consideration.

On the subject of track workers, I've heard of a device that can be held up to tell whether an overhead line is energised. I wonder whether there is something that can be devised for the third rail.

I saw a thing on TV some years go and LT track workers had a device with a load of bulbs in it all in parallel. It sat across the 2 live rails. When the current went off the bulbs went out. I think the assumption was that if all 6 bulbs went phut, it wasn't your day!.
But a simple and effective device for detecting if the juice is off. I imagine a short circuiting bar would also be used.

 

[HSTEd]

On the subject of track workers, I've heard of a device that can be held up to tell whether an overhead line is energised. I wonder whether there is something that can be devised for the third rail.

Historically such apparatuses existed, but they were withdrawn because they were simple lamps and were not fail safe as a result. (If the rail was live they would glow, but would obviously not glow if the lamp was broken)

The recent "DECARB" study proposed the development of a fail-safe successor to that equipment

 

[yorksrob]

Historically such apparatuses existed, but they were withdrawn because they were simple lamps and were not fail safe as a result. (If the rail was live they would glow, but would obviously not glow if the lamp was broken)

The recent "DECARB" study proposed the development of a fail-safe successor to that equipment

That would be a sensible and worthwhile development. I can understand track staff being wary of relying on someone else to turn the current off.

 

[D365]

On the subject of track workers, I've heard of a device that can be held up to tell whether an overhead line is energised. I wonder whether there is something that can be devised for the third rail.

"Test before touch" is a critical feature of all track work on electrified routes, be it overhead or third/fourth rail. But it's not 100% foolproof. Adjacent lines can remain energised or be accidentally re-energised.

 

[AM9]

Well that's not strictly true given the existance of modern SCADA.

Indeed London Underground managed to escape the third rail (de-facto) prohibition by establishing safety procedures to eliiminate trackside staff with the conductor rail live.

A difference that I acknowledged earlier. LU was also aided by the fact that their tracks are pretty well segregated from the general public (e.g. very few crossings and of course the tunnels are in practice effectively inaccesible to trespassers). As you say, the controls and monitoring of the assets minimise any access to the live track. Indeed, the very limited clearances along much of the network makes work with any on track work during service running virtually impossible.

 

[yorksrob]

I saw a thing on TV some years go and LT track workers had a device with a load of bulbs in it all in parallel. It sat across the 2 live rails. When the current went off the bulbs went out. I think the assumption was that if all 6 bulbs went phut, it wasn't your day!.
But a simple and effective device for detecting if the juice is off. I imagine a short circuiting bar would also be used.

That does sound like a good solution.

 

[eldomtom2]

Which is why safety engineering exists.

Safety engineering is not what determines what is "reasonably practicable".

 

[Snow1964]

Am I reading it correctly that the draft charges for CP7 have third rail as half that of ac electrification

Per page 19
ac OLE is 2.56 pence per mile
dc third rail is 1.26 pence per mile

If so why would any user prefer to convert dc route to ac

https://sacuksprodnrdigital0001.blob.core.windows.net/periodic-review-23/Presentation%20to%20industry/CP7%20Passenger%20Access%20Charges%20-%20DD%20Stakeholder%20workshop%2001.08.23.pdf

 

[Bald Rick]

Am I reading it correctly that the draft charges for CP7 have third rail as half that of ac electrification

Per page 19
ac OLE is 2.56 pence per mile
dc third rail is 1.26 pence per mile

If so why would any user prefer to convert dc route to ac

https://sacuksprodnrdigital0001.blob.core.windows.net/periodic-review-23/Presentation%20to%20industry/CP7%20Passenger%20Access%20Charges%20-%20DD%20Stakeholder%20workshop%2001.08.23.pdf

That’s the asset usage charge, not the electricity bill

 

[AM9]

That’s the asset usage charge, not the electricity bill

That did seem incredibly cheap for a loco or EMU which could draw up to 5MW!

 

[Bald Rick]

That did seem incredibly cheap for a loco or EMU which could draw up to 5MW!

Well quite. A 10 car train from Southend to Liverpool Street would be charged a shade over a tenner for the electrification asset usage charge. The power for the trip will be 10-20 times that.