New installations or extending 3rd rail

[Aictos]

Is there a ban of extending 3rd rail or installing new 3rd rail routes?

Just wondering on the ELL to Dalston Junction got done that's all.

Is there isn't such a ruling then could not the North Downs be electrified to the 3rd rail system?

 

[ralphchadkirk]

Completely new installations are not allowed - extensions are.

 

[yorksrob]

I'm sure there's not a ban on extending the third rail. It was being extended regularly on the Southern into NSE years. They certainly don't like putting it anywhere totally new though.

I think it's just a matter of funding problems and different priorities as to why the gaps on the Southern and the extremities of Merseyrail haven't been done yet.

 

[Wyvern]

I believe ground level supply rails are not allowed under EU regulations.

Existing British third rail has grandfather rights for possibly extensions but certainly "filling in".

 

[yorksrob]

I believe ground level supply rails are not allowed under EU regulations.

Well, that's a good enough reason to install a few more AFAIK

 

[MikeWh]

I believe ground level supply rails are not allowed under EU regulations.

Existing British third rail has grandfather rights for possibly extensions but certainly "filling in".

Interesting. Is that any kind of ground level supply, or just upward facing? Was the DLR started before the regulations were made?

 

[WatcherZero]

As I understood it was just a Dft moratorium on new 3rd rail routes to limit its spread because of wider network compatability and general feeling it is inferior while extending existing lines is allowed.

 

[Bastiaan]

I believe ground level supply rails are not allowed under EU regulations.

There are still lots of metro lines with 3rd rail operation being built in the EU

 

[ainsworth74]

There are still lots of metro lines with 3rd rail operation being built in the EU

New build or extensions? Because it's only new build that's no longer allowed.

 

[jopsuk]

If it is banned by the EU, there will be an EC directive. They are all, as far as I know, publicly available in the internet. Why not go and find it? It'll help back up your argument...

 

[swt_passenger]

Or just read the Network Rail 'Electrification RUS'. It clearly identifies which lines would be electrified with third rail, which OHL, and which are 'to be decided'. The latter includes Salisbury - Exeter - where they intimate that it would probably be AC, but don't say it MUST be AC, so I'd suggest relatively long extensions might be allowed.

But for the North Downs route, which started the original discussion:

Gap A3.1 Wokingham to Ash and Shalford to Reigate
Option A3.1 Electrify Wokingham to Ash and Shalford to Reigate with DC electrification. Convert Reading to Gatwick Airport and Reading to Redhill local services to electric traction.

 

[brad465]

providing 3rd rail is allowed to be extended, I'm pleased

 

[tbtc]

Would we be allowed to "fill in" the stretch between Basingstoke and Chester then?

This could be one of those bits of "received wisdom", like "Pacers aren't allowed on Third Rail lines, where nobody knows the real source to "confirm"...

 

[Lampshade]

This could be one of those bits of "received wisdom", like "Pacers aren't allowed on Third Rail lines, where nobody knows the real source to "confirm"...

We all know that's rubbish, 142s go through Hunts Cross all the time. It's an excuse to keep them away from London.

 

[Old Timer]

3rd rail electrification by its very nature is very expensive when compared to OHL Equipment.

Any long distance expansions would take a long time to recover the investment, and would increase considerably the track access costs.

There is no easy solution I am afraid.

 

[yorksrob]

I suppose at least all of the prospective third rail routes are relatively short infills (with the exception of Basingstoke - Exeter of course. Perhaps they could electrify as far as Salisbury and develop some sort of push - pull operation again for anything further west ).

 

[asylumxl]

It is my uninformed opinion that it'd make sense just to go all the way 3rd rail to Exeter. It would mean SWT could utilise their existing stock to the best possible. Also, 444s would be nice on the route .

 

[jopsuk]

Or, if the GWML electrification goes to Exeter, wire up the south west route and add the OHL equipment to the appropriate stock.

 

[yorksrob]

Yes, come to think of it, dual voltage electrics are a tried and tested technology. Have the changeover at Salisbury then most of the stoppers wouldn't need altering.

 

[swt_passenger]

It is my uninformed opinion that it'd make sense just to go all the way 3rd rail to Exeter. It would mean SWT could utilise their existing stock to the best possible. Also, 444s would be nice on the route .

There isn't any existing electric stock sitting around spare for use on newly electrified routes. That's the main reason SWT use 158s and 159s on third rail only routes already.

Your suggestion might have made sense if you'd simply said that more 444s and 450s should be obtained for Exeter and Salisbury stoppers respectively, allowing existing DMUs to be cascaded.

 

[WatcherZero]

Since im sure Merseyrail wont get new rolling stock in present climate, are the 508's going to go back to the Mersey?

 

[Jan]

Interesting. Is that any kind of ground level supply, or just upward facing? Was the DLR started before the regulations were made?

I these regulations don't apply to the DLR because it uses bottom-contact 3rd rail.

 

[Class377/5]

I these regulations don't apply to the DLR because it uses bottom-contact 3rd rail.

And its encased in plastic (except the underneath) so you can safely cross it where as the 3rd rail on the rest of the network is all exposed.

 

[scrapy]

Would we be allowed to "fill in" the stretch between Basingstoke and Chester then?

This could be one of those bits of "received wisdom", like "Pacers aren't allowed on Third Rail lines, where nobody knows the real source to "confirm"...

Pacers are used on 3rd rail at Hunts Cross and Chester without any problem.

 

[swt_passenger]

Pacers are used on 3rd rail at Hunts Cross and Chester without any problem.

Yes, but Basingstoke is in the South East .

We have much higher standards expected of our rolling stock round here, I'll have you know...

 

[tbtc]

Pacers are used on 3rd rail at Hunts Cross and Chester without any problem.

Yeah, I was meaning that lots of people believed that they weren't allowed on 3rd rail lines (despite the evidence), and it becomes a kind of "received wisdom" where we accept information as fact without having anything to back it up...

...similarly, I'd not actually seen anything saying more 3rd rail wasn't allowed (apart from infills), so wasn't sure if there was evidence it wasn't allowed, or other reasons for it not happening (e.g. cost)

 

[Kneedown]

Yeah, I was meaning that lots of people believed that they weren't allowed on 3rd rail lines (despite the evidence), and it becomes a kind of "received wisdom" where we accept information as fact without having anything to back it up...

I knew what you meant

As regards expanding the third rail, i believe the main argument against it is the cost, as OT already pointed out. I'm not an electrical expert but apparently you need a lot more feeder stations with a 3rd rail dc network than you do with an ac overhead system. I can see why that would cost more, but on the other hand i'd have thought that the live rail would be a set distance from the running rail, and so less planning on where it's going to go (as opposed to deciding how many overhead gantries and their postioning for instance, raising bridges etc) would be required as well as less basic infrastructure, but there you go.
Having said that it would surely be more economical to extend electrification on the Southern and Mersey systems, than it would to rip the whole lot up and replace with overhead.

 

[daikilo]

Would we be allowed to "fill in" the stretch between Basingstoke and Chester then?

This could be one of those bits of "received wisdom", like "Pacers aren't allowed on Third Rail lines, where nobody knows the real source to "confirm"...

Basingstoke to Chester: No. It won't work as you are suggesting linking 2 completely independent networks with no obvious significant traffic flows and not a fill-in extension. That said, e.g extending Mersyrail or Southern Electrics beyond their current boundaries might work for the same reason.

 

[A60K]

I'm not an electrical expert but apparently you need a lot more feeder stations with a 3rd rail dc network than you do with an ac overhead system.

It's basically because the current on a third rail system is so much lower than on overhead - 750V against 25,000V. AIUI the lower power means more current needs to be supplied, in turn meaning more frequent feeder stations. I'm not sure of the exact distances between feeder stations, and they'll vary according to the number of trains expected in section, but I think it's something like every 3-5 miles on 750V DC, compared to perhaps every 10-25 miles on 25kV AC.

 

[button_boxer]

It's basically because the current on a third rail system is so much lower than on overhead - 750V against 25,000V. AIUI the lower power means more current needs to be supplied, in turn meaning more frequent feeder stations. I'm not sure of the exact distances between feeder stations, and they'll vary according to the number of trains expected in section, but I think it's something like every 3-5 miles on 750V DC, compared to perhaps every 10-25 miles on 25kV AC.

You've got your voltage, current and power mixed up but basically yes.

Power = voltage x current - the voltage is lower on third rail, so trains draw much higher current for the same amount of power. The higher the current the lower the transmission efficiency. At higher current a lot more energy is wasted in transmission (as heat, essentially you're heating up the transmission cables), which is why the feeders have to be closer together.