New 3rd rail safety improvements?

[74A]

I know it's very difficult/impossible to get new 3rd rail electrification due to the danger of the live rail.

With current technology would it not be possible to only energise it when a train is in a section and have it off when no trains are running ?

Obviously not a perfect solution but would reduce the risk of electrocution somewhat.

 

[zwk500]

This comes up on nearly every discussion, and to do it you'd need so many sections over the scale of the southern's network. You'd also need the switchgear to be capable of turning the sections on and off at speeds of up to 100mph.

In short, it'd cost a fortune to install, drain money like a sink to maintain and would present an unacceptable operational risk to train performance. For the money it'd involve, you'd be better converting smaller stretches to OLE.

 

[LNW-GW Joint]

The Alstom APS system seems to work on metro systems in places like Bordeaux and with the new Sydney Light Rail L2/L3 lines in the city centre.
The Sydney system only covers about 2km of slow-speed street running from Town Hall to Circular Quay, with OHLE elsewhere.
It avoided installing wires in the city centre.
It's difficult to identify a similar location in the UK - maybe in places like Bristol or Leeds city centres.
Alstom APS - Wikipedia
CBD and South East Light Rail - Wikipedia

The section between Town Hall and Circular Quay is wire-free, with trams using Alstom's proprietary APS technology to run instead.[18]

This was originally to have been achieved by equipping the trams with batteries and providing recharging facilities at stops.

 

[swt_passenger]

The Alstom APS system seems to work on metro systems in places like Bordeaux and with the new Sydney Light Rail L2/L3 lines in the city centre.
The Sydney system only covers about 2km of slow-speed street running from Town Hall to Circular Quay, with OHLE elsewhere.
It avoided installing wires in the city centre.
It's difficult to identify a similar location in the UK - maybe in places like Bristol or Leeds city centres.
Alstom APS - Wikipedia
CBD and South East Light Rail - Wikipedia

It doesn’t “scale up“ to mainline train lengths, speeds, or current draw. It was only discussed a few weeks ago. Those systems AIUI aren’t to deal with the dangers of third rail, but the unwanted visual effects of catenary.

 

[zwk500]

It doesn’t “scale up“ to mainline train lengths, speeds, or current draw. It was only discussed a few weeks ago. Those systems AIUI aren’t to deal with the dangers of third rail, but the unwanted visual effects of catenary.

Indeed, you've put a rather helpful description here: https://www.railforums.co.uk/threads/3rd-rail-infill-suggestions.217800/page-5#post-5158057

 

[AM9]

This comes up on nearly every discussion, and to do it you'd need so many sections over the scale of the southern's network. You'd also need the switchgear to be capable of turning the sections on and off at speeds of up to 100mph.

In short, it'd cost a fortune to install, drain money like a sink to maintain and would present an unacceptable operational risk to train performance. For the money it'd involve, you'd be better converting smaller stretches to OLE.

Add to that, not only would it be far more expensive than a decent OLE conversion, - it would also do nothing to improve the substandard capacity and performance of 3rd rail low voltage power delivery anyway. I casn only think of one fully operational installation where the 3rd rail supply is switched per train on demand and that is in the Thameslink core between Farringdon and City Thameslink, - and that was put in at great cost to ensure either ac or DC can be used with their necessary incompatible safety earth earth arrangements but without causing damage to the surrounding infrastructure. It is nothing to do with track access safety.

 

[D365]

The issue remains that you can’t guarantee a particular section of rail is turned off, until the entire section is isolated. Track workers would still have to treat the section as live.

 

[alf]

Several thousand trains a day use third rail in England, with journeys up to 130 miles perfectly safely day after day, year after year.

It is an economical, safe,system for passengers trains up to 90 mph. But not practical for heavy freight trains.

25kv wires down are highly disruptive & not rare events.
Displaced conductor rails are very rare & do not cause wholesale network cancellation.

Network Rail have admitted that their stats, which led them to claiming a few years ago that third rail was eight times more dangerous than overhead ac, are unreliable.

And that eight times figure was a subjective weighted index which gave undue weight to injuries, even minor ones like a sprained foot from tripping on a third rail. All contact with AC leads to death. Contact with DC is often survivable. So unfair to assessment of third rail.
The network rail stats are not reliable enough to judge. They have been told to reassess the issue.

If the Uckfield line/Rye lines were third railed then it would be prudent to replace foot crossings with bridges.
But that would probably be done with 25kv electrification too, or if quiet battery power units were introduced.

The end of third rails could be terminated in yellow insulation.

Versus 25 Kv, for non 110 mph lines & heavy freight, tried & tested third rail is far cheaper to build, cheap to run & probably as safe. And it is fast to build. We need more electrification now.

 

[zwk500]

Several thousand trains a day use third rail in England, with journeys up to 130 miles perfectly safely day after day, year after year.

It is an economical, safe,system for passengers trains up to 90 mph. But not practical for heavy freight trains.

25kv wires down are highly disruptive & not rare events.
Displaced conductor rails are very rare & do not cause wholesale network cancellation.

Although other damage to conductor rails, or poor traction draw due to ice/leaf mulch is common and does cause widespread disruption

Network Rail have admitted that their stats, which led them to claiming a few years ago that third rail was eight times more dangerous than overhead ac, are unreliable.

And that eight times figure was a subjective weighted index which gave undue weight to injuries, even minor ones like a sprained foot from tripping on a third rail. All contact with AC leads to death. Contact with DC is often survivable. So unfair to assessment of third rail.
The network rail stats are not reliable enough to judge. They have been told to reassess the issue.

Third rail is at perfect trip height and a constant danger. OLE is 4.5m above the ground. And just because DC isn't always fatal doesn't mean it's a negligible impact. There's other people on here who can give examples, but it will suffice to say the dangers of DC should not be downplayed.

The end of third rails could be terminated in yellow insulation.

The ends aren't the problem. It's the short distance between the con rail and running rail.

Versus 25 Kv, for non 110 mph lines & heavy freight, tried & tested third rail is far cheaper to build, cheap to run & probably as safe. And it is fast to build. We need more electrification now.

Versus 25KV OLE, 3rd Rail is often more expensive on a whole-life basis as you need more substations and much more maintenance.

 

[RobShipway]

I would have to go along with Zwk500 when he says that you are better to be inserting OLE, then putting in 3rd rail. My conclusion is not just on cost, but on safety as well. Even though you can still have accidents with OLE where people get electrocuted, it is more likely to happen when people touch the conductor rail for 3rd rail. It is also worth noting that Zwk500 actually works within the industry, hence why he is able to say without a doubt that OLE costs less to install than 3rd rail, even if there is 3rd rail near to the line to be electrified.

 

[zwk500]

It is also worth noting that Zwk500 actually works within the industry, hence why he is able to say without a doubt that OLE costs less to install than 3rd rail, even if there is 3rd rail near to the line to be electrified.

While your support is appreciated, I don't claim 'without a doubt'! I do not work for the electrification teams, nor do I do project costings. It's entirely possible that local conditions such as ground stability, over-line obstacles and the length to be electrified would make 3rd rail cheaper in certain instances.

 

[30907]

The issue remains that you can’t guarantee a particular section of rail is turned off, until the entire section is isolated. Track workers would still have to treat the section as live.

Belatedly answering the original question:

Looking at Brading station recently, I noticed that near the foot crossing the 3rd rail has protective boards in yellow (plastic) on both sides (there are also the usual "cattle grid" boards). If this were standardised through all stations and at other access points it would considerably reduce the risk of accidental contact.

It wouldn't address the situation of track workers, admittedly (unless you extended the boarding throughout, which would be expensive....

 

[mmh]

Belatedly answering the original question:

Looking at Brading station recently, I noticed that near the foot crossing the 3rd rail has protective boards in yellow (plastic) on both sides (there are also the usual "cattle grid" boards). If this were standardised through all stations and at other access points it would considerably reduce the risk of accidental contact.

It wouldn't address the situation of track workers, admittedly (unless you extended the boarding throughout, which would be expensive....

I don't know the station, so I don't know why the 3rd rail is boarded here, but it's a common myth on the forum that such boards are (only) installed as protection against contact with the rail. They're commonly used in areas where an emergency short-circuiting bar is not to be used - usually to protect the signalling system. In locations where boarding is impossible the rail is often painted yellow on the side to denote this - which obviously does nothing to prevent accidental contact with it.

 

[Bald Rick]

Add to that, not only would it be far more expensive than a decent OLE conversion, - it would also do nothing to improve the substandard capacity and performance of 3rd rail low voltage power delivery anyway. I casn only think of one fully operational installation where the 3rd rail supply is switched per train on demand and that is in the Thameslink core between Farringdon and City Thameslink, - and that was put in at great cost to ensure either ac or DC can be used with their necessary incompatible safety earth earth arrangements but without causing damage to the surrounding infrastructure. It is nothing to do with track access safety.

Strictly speakin, the system between City TL and Farringdon doesn’t switch the 3rd rail supply, which is live at all times. The switching is of the return current path.

Displaced conductor rails are very rare & do not cause wholesale network cancellation.

Just the two major conductor rail incidents today. How many cases of the wires coming down are there today?

 

[AM9]

Strictly speakin, the system between City TL and Farringdon doesn’t switch the 3rd rail supply, which is live at all times. The switching is of the return current path. ...

Yes I was aware that it was to provide correct earthing for both OLE and 3rd rail, (not at the same time) but I presume that the switchgear is rated for traction currents and the local supply there is a high current one, maybe in the same range as a feed on a fast mainline, (with corresponding high costs).
As an aside, I assume that the 25kV is fed from just north of the core so other than isolation kit, there's no high power ac feed there. Is that correct?

 

[Bald Rick]

Yes I was aware that it was to provide correct earthing for both OLE and 3rd rail, (not at the same time) but I presume that the switchgear is rated for traction currents and the local supply there is a high current one, maybe in the same range as a feed on a fast mainline, (with corresponding high costs).
As an aside, I assume that the 25kV is fed from just north of the core so other than isolation kit, there's no high power ac feed there. Is that correct?

The D.C. is fed from a massive sub in the core - which supplies a fair bit further south too.

The AC is fed from Grahame Park (near Hendon).

 

[CBlue]

You don't have to switch AC overhead lines off when someone trespasses for a start...

"But ah! Surely it's their own fault if they get zapped by 750V DC!" I hear someone cry. Easier to make that judgement from behind a keyboard at a comfy desk chair with no repercussions for the decision, no? Be that rash in reality and employment is rather hard to come by.

 

[AM9]

The D.C. is fed from a massive sub in the core - which supplies a fair bit further south too.

The AC is fed from Grahame Park (near Hendon).

Thanks.

 

[Gareth]

You don't have to switch AC overhead lines off when someone trespasses for a start...

"But ah! Surely it's their own fault if they get zapped by 750V DC!" I hear someone cry. Easier to make that judgement from behind a keyboard at a comfy desk chair with no repercussions for the decision, no? Be that rash in reality and employment is rather hard to come by.

But the thread is about safety improvements to third rail. Not whether or not it's safer/better than OHLE.