DfT Study - Low Cost Electrification of Branch Lines

[HSTEd]

It is funny to see the angst of testing 12 car/3 pan 350s on the WCML, compared to this much cheaper ohle

I believe a full 16 carriage 0 Series Shinkansen set would run at 140mph with eight pans up, which is rather amusing

 

[Holly]

750vDC overhead would be a good fit for Wrexham-Bidston-Birkenhead. Since 750vDC overhead and 750vDC third-rail will co-exist on the same stretch of track fuss free.

 

[Nym]

750vDC overhead would be a good fit for Wrexham-Bidston-Birkenhead. Since 750vDC overhead and 750vDC third-rail will co-exist on the same stretch of track fuss free.

But then why not just lay 3rd Rail?

If they actually want to entertain the idea of a two tier OHL electrification system with 750VDC OHL and 25KVAC OHL co-existing then we need to have a proper changeover system designed for some new type of dual voltage stock.

Proberbly with a changeover in the station, and if there is to be no time without power for the unit it would need either a massive power electronics package or some kind of 3rd rail placment at the trackside for use during the switchover.

I'm not entirely fermiliar with the current changeover system s in use on the mainline but if the unit can live without power for 10 seconds or so at the changeover then it will be entirely possible to changeover on the fly or when stationary (if two pantographs where provided, aswell as an interunit rail for power transfer when only one set is drawing power), the unit would need to have a transformer and a power equipment changeover system. But it shouldn't be too hard to implement on a new 3 or 4 car unit. So long as there where precise stopping points provides and rather large neutral zones the length between the LV and HV pantographs for changeover.

I'd only support this on the condition though that this would be provided and any point on the mainline it will changeover to 25KVAC OHL for the langth of it being a mainline. For example, a changeover at Oxenhome on platform 1, Bolton at Hai'th'th Wood, Carnforth on the WCML etc.

But I don't see any reason why this wouldn't be possible...

 

[HSTEd]

What do you define as a "mainline"? The Cornish Main Line between St Austell and Par is highly unlikely to ever be electrified unless its part of some grand scheme to end Intercity Diesel traction entirely which isn't going to happen thanks to the IEP locking it in. Putting up 25kV for that section of track would kill the project since remember the project only allows 500kW for each train so every tonne of extraneous equipment (like transformers and whatnot) counts against it. And four car units are definately out, its a big enough challenge to get a two car unit that isnt a tram on that much juice.

Also why would you need two pantographs? once the pantograph is in the neutral zone it can be switched from connecting to the transformer to whatever the DC traction control equipment uses (the choppers?) using a pair of contactors.

Edit: Either way I do like the idea of a 25kV installation using this low cost equipment, and my estimate for the Harrogate line probably assumed rather too much stock, as if they are brand new EMUs they would probably need less reserve trains to cover failures and maintain service than the D stock estimate.

If we assume 5 car 20m EMUs (like an Electrostar) and the existing ~2:30 round trip journey time with 30 minutes slack/turnaround, a 15 minute service would require 12 sets, so Il say 16 sets to maintain reasonable reliability. That comes to 80 carriages rather than 150, so cutting the total cost of the project to roughly £110 million.

So 25kV electrified 5 carriage brand new EMUs running on the Harogate line for 2/3rds what the tube line project is supposed to cost.

Howzattt?

 

[Holly]

But then why not just lay 3rd Rail? ...

Cost.
750vDC overhead is cheaper to install than either third rail or 25kVAC, at least in above-ground lines. Of course it is generally less powerful.

Changeover, 25KvAC OHLE to/from 750vDC overhead is largely impractical, for a number of reasons. 750vDC overhead really only suits segregated tram-like systems and lightly loaded rural lines.

 

[mallard]

If they actually want to entertain the idea of a two tier OHL electrification system with 750VDC OHL and 25KVAC OHL co-existing then we need to have a proper changeover system designed for some new type of dual voltage stock.

Proberbly with a changeover in the station, and if there is to be no time without power for the unit it would need either a massive power electronics package or some kind of 3rd rail placment at the trackside for use during the switchover.

I'm not entirely fermiliar with the current changeover system s in use on the mainline but if the unit can live without power for 10 seconds or so at the changeover then it will be entirely possible to changeover on the fly or when stationary (if two pantographs where provided, aswell as an interunit rail for power transfer when only one set is drawing power), the unit would need to have a transformer and a power equipment changeover system. But it shouldn't be too hard to implement on a new 3 or 4 car unit. So long as there where precise stopping points provides and rather large neutral zones the length between the LV and HV pantographs for changeover.

While it may be slightly more electrically complex, there's no real reason why it couldn't be done instantaneously, on the move and with only one pantograph. You could eliminate most of the electrical complexity with a short neutral section and an induction/magnet system to tell the train to switch.

 

[Schnellzug]

I Daresay Bombardier, Siemens, Alstom etc would know all about voltage changeovers, since multi-voltage equipment is virtually standard for all new locos now, at least.

 

[mallard]

There are a decent number of 1500v DC/25kv AC dual-voltage units on the continent, but I can't find any that do it with a single pantograph (particularly since English-langauge documentation about these is limited). I suspect that part of this is due to different pantograph specifications on the different electrification systems.

Since class 307 units kept their pans when they were converted from 1500v DC to 25kv AC, it's clear that a single pan could be used, if there were a switching mechanism. I expect the main reason it's never been done is for electrical simplicity and prevention/limitation of damage if an incorrect voltage were selected.

 

[apk55]

Dual voltage 750V/ 25KVAC units should not be a problem and changeover would be done at a neutral section where the unit coasted over a short gap in the overhead a few meters long. Two pantograph's would probably be required as AC systems use carbon wear strips and low contact pressure as they only carry a few amps, where as DC systems with much higher currents so higher contact pressure and wider contact strips is required.

Karlsruhe (Germany) has some trams that can run on 750V tram lines and mainline railways with 15KVAC 16.7Hz electrification so it can be done
http://en.wikipedia.org/wiki/Stadtbahn_Karlsruhe

A low power of 500KW I think is much to low, it is only the power of a typical two car DMU so the performance would be restricted if 3 or 4 car trains are to be considered. It would rule out the possibilities of using recycled units from the main line or TFL unless they were modified. Therefore I still think 25KVAC would be the best system.

 

[mallard]

A low power of 500KW I think is much to low, it is only the power of a typical two car DMU so the performance would be restricted if 3 or 4 car trains are to be considered.

Except that a lightweight "tram-like" EMU will be much lighter than a two car DMU. E.g. a DLR EMU is about 36 tons, about the same as one car from a Cl150.

 

[HSTEd]

Dual voltage 750V/ 25KVAC units should not be a problem and changeover would be done at a neutral section where the unit coasted over a short gap in the overhead a few meters long. Two pantograph's would probably be required as AC systems use carbon wear strips and low contact pressure as they only carry a few amps, where as DC systems with much higher currents so higher contact pressure and wider contact strips is required.

Wait, don't 373s do 1500V, 3000V and 25kV with the same pantograph?

 

[Mintcake Maker]

Hi all long time lurker, first time poster. You can probably guess where I’m from by my name and since I’m also a university student I do a lot of travel by rail. So reading this thread got me thinking about the Windermere branch and possible electrification and solutions to said problems.

Firstly I must say that I would sooner have any money that could possibly spent on electrification on the line used to create a passing loop to increase the frequency of the trains too every 30 minutes as opposed to the current 1tph. Id also have to say for the branch I’d like to see either 3rd rail 750V DC or 25kv OHLE used, I just think that in this current climate we should make best use of what we have as we won’t have lots of money to spend on “new” 750V DC OHLE. I would also let the branch line be run by Northern Rail after the franchises are re-drawn as I don’t believe it to be a FTPE route. So these are my ideas, all assuming a passing loop is constructed.

Hybrid 25kV
I quiet like the “hybrid” 25kV OHLE on lightweight poles idea. Firstly the line is now mainly a self contained shuttle, but like others have pointed out it does have a handful of through services to MIA. I would also wire the siding coming off the up passing loop at Oxenholme (?, have I got this right). It’s about 150m long which is just long enough to allow 2x class 323’s to be stabled there overnight (after the LM’s 323’s are transferred to NR). The 3 or 4 times daily MIA run could be carried out by a slightly longer 319 with 1st class accommodation or another DMU tagged onto their proposed BIF-MIA service. Maybe some new build 2 car EMUs based on a Class 466 design could be built?

However there are 2 major problems I foresee with this option. They are; how well would the hybrid/cheap OHLE equipment fair in the wild weather that happens in the Lake District and secondly the capacity of 323’s would be (very) underused on the shuttle service. Also what about the environmental campaigners who would complain that the OHLE gear was spoiling the natural landscape (not my opinion as I think electric trains would be better than diesel). On the bright side even using the most expensive pricings by HSTEd it would only cost about £7m to do the entire branch line.

750V 3rd rail
The 3rd rail idea is an interesting one. It would not spoil the natural landscape and for the most part the line is very well segregated meaning that risk of electrocution is lower. However the disadvantage is that in bad weather or deep snow the 3rd rail may be iced/snowed over, but we could always modify the collecting gear to allow us to operate either a bottom contact, or covered top contact system. I’m guessing the cost of laying a 3rd rail DC system can’t cost that much more than the 750v DC OHLE?

http://www.railway-technical.com/3rd002.gif

We could then run a couple of 456’s or 466’s for a half hourly service on the line, with still good capacity. Can the 508/7 be run in just a 2 car formation? If so id even take a couple of them on the line and therefore share large overhauls and maintenance at Merseyrail depots. If the 25kV OHLE was extended from the mainline to cover the entire length of platform 3 then we could still run 3 MIA trains a day using 1 single Northern Rail 319. Again we could lay 3rd rail into the siding off the up-line passing loop or re-lay the short section of track that once stood where the new car park is to allow us to create an overnight stabling point.


I think that both these methods could be employed both quickly and cheaply and could over enhance the line and service provide. Especially since it’s just been reported that the pollution levels in Kendal have yet again risen and have broken UK air quality regulation, a more frequent service may tempt more local people back to the train instead of using the car.

So could any of the 2 above suggestions actually be employed on the line and more importantly how likely could it be especially since the government is now offering £5bn for public infrastructure projects. I suppose if it’s cheap enough (I’m not sure how much other things would cost like turning the siding into a proper stabling point, any info on costings such as cost of laying track or buying equipment etc would be very much appreciated) it has a very good chance of happening.

Sorry for the mad ramblings, hope they make sense

 

[boing_uk]

Christ! Buried wooden poles are around £4500 cheaper than what they are currently using?! How much does a catenary stanchion cost?!!

For £4500, I can buy an 16m electric winch trolley-head CCTV tower, delivered and installed, excluding the base. And there is a serious amount of steel in one of those things. For an extra £1000, I get the foundation which is 1.5m cube of concrete.

Let us not forget that a telephone pole style support is pre-bored and then forced in to the ground. If we are going down the route of having a rotary machine, might as well use a screw pile. I can tell you now that you can get a Lattix mast, for about £3k, with maybe another £750 for the screw piles. That is for a single installation, so I can imagine bulk would cause significantly reduced prices.

 

[HSTEd]

Oh and I just realised: if you switch to composite utility poles (currently a bit expensive, but getting cheaper and still far cheaper than metal posts at £800 installed rather than ~£400 for wood - this is discounting that the lighter composite poles are probably easier to install and are effectively zero maintenance) you can discard the insulators entirely as they become unneccesary.
It doesn't matter if your cantilever structure is live at 25kV since its not attached to a conductor and its 10 feet off the ground. This most likely pays for the composite post and allows for a lighter cheaper cantilever and reduces turning moment on the posts for single track installations.

EDIT:
The screw piling actually costs quite a lot of money, the telephone pole does it by digging a hole, dropping the pole in and backfilling.
I believe there was a post somewhere about how various litigation threats have led to people piling safety margin on safety margin on safety margin so that everything is drastically over specification.

 

[boing_uk]

I beg to differ on the cost of screw piling - they are cheaper than a conventional in-situ foundation and certainly quicker to install. We use them for even small signposts all over the place.

Composite poles, such as Jerol, have to be very specifically designed and also you have to be very careful when designing for wind loads. They also require a significant and solid foundation - you would be looking at something between a 240mm and 300mm diameter post to cater for the load of the OLE and also dynamic loads.

 

[HSTEd]

I beg to differ on the cost of screw piling - they are cheaper than a conventional in-situ foundation and certainly quicker to install. We use them for even small signposts all over the place.

Composite poles, such as Jerol, have to be very specifically designed and also you have to be very careful when designing for wind loads. They also require a significant and solid foundation - you would be looking at something between a 240mm and 300mm diameter post to cater for the load of the OLE and also dynamic loads.

The pole would have no foundation to speak of, it would be straight in teh ground (the wooden posts ordered would be 9m long which says something), the report mentions Composite Poles as the preferred solution and suggests that the support could be made viable with roughly 200mm diameter poles which are apparently something of a standard in the industry, especially in the US, the extra costs of the poles are, as I said, defrayed in part by the simplifications to the equipment allowed.

And if its a twin track line lateral loading from the weight of the equipment itself can be balanced by positioning the posts between the tracks and mounting on cantilever on each side.

EDIT: Screw piling requires that the screw element is fitted to the bottom of the post and is only used once, with an auger you can reuse the screw peice over and over again and simply drop a plain pole into the hole you just made.

Apparently "Tram Power Ltd" tested using an auger and utility poles and managed to lay 24 over 2 days using a single team, which is something like 750m per day per team.

 

[boing_uk]

Yes, we use screw piles for passively safe posts - makes for easy replacement after a road traffic collision. But moreover, the installation is easy too as you have one team installing the screws, another team installing the posts.

Looking at some of the networks earthworks, would we really trust a directly buried pole to remain in place? At least a piled foundation provides a modicum of stability. Directly buried and backfilled really is relying on the stability of the surrounding material and given the tolerances for OLE and the dynamic loads likelty to be encountered, is that a good thing for the maintenance crews or the longevity of the equipment itself?

 

[HSTEd]

These poles are supposed to be used only at relatively low speeds so the dynamic loads are probably not going to be as large as they are on places like the WCML and ECML. In addition buried wooden poles are used on atleast one railway line in America, that being the "Black Mesa and Lake Powell" railroad where any overturning loads on that single track line are dealt with by the simple expedient of guying the posts to varying extents, although the report suggested that this could be partially prevented by balancing the static loads and leaving only the dynamic loads on the post itself or by pouring concrete around the post while it is in the hole, which although costs a significant amount of money is still far cheaper than piled foundations,

Ofcourse in a british loading guage the wiring is going to be at most 3m (that correct, im not sure) over the track which would leave atleast half of a nine meter post buried in the ground which has got to be rather stable, especially considering the amount of wire they hold up in there normal application against considerable wind and weather loadings.

EDIT: Apparently the hybrid catenary arrangement we are discussing his been up, mounted on buried wooden poles for all of atleast one winter at "Carnforth Railway Centre" which apparently had severe storms although I have no idea if they have been testing it intensively.

EDIT: IMO, the DfT should fund a study on the concept of using hybrid overhead equipment at 25kV (more expensive than this proposal but not by much) and possibly even fund a test installation on somewhere like the Ely to Peteborough Line, as that is the sort of "fill in the gap" exercise where lower cost wiring could really come into its own.

 

[boing_uk]

UK OLE is 4m or so above the rail level; then add 1.5m or so for the registration arms, then add another 1m or so below rail level to reach formation level in the cess in most places - sometimes more. So perhaps 8m above formation level in the worst case scenarios, 7m at best.

If planted on the embankment slope, like many OLE structures are, you are looking at needing longer posts than 9m. But hell these are minor details and the report is hardly a specification.

 

[HSTEd]

Either way, its definately a lot cheaper than the conventional system which is an enormous block of concrete on a huge steel post.

 

[Trog]

And if its a twin track line lateral loading from the weight of the equipment itself can be balanced by positioning the posts between the tracks and mounting on cantilever on each side.

Thats two tracks blocked until you clear your poles out of the structure gauge.



The other question about wooden poles is how much does it cost to keep checking them for rot, and replacing them when they do.

One thing all these cheap ideas don't get round is the cost of immunising the signalling, and that costs big money.

 

[mallard]

One thing all these cheap ideas don't get round is the cost of immunising the signalling, and that costs big money.

Somehow, I don't think mechanical token-block systems suffer much from electrical interference...

 

[Nym]

Might cause interference to the Signaller's tele?

 

[HSTEd]

Thats two tracks blocked until you clear your poles out of the structure gauge.



The other question about wooden poles is how much does it cost to keep checking them for rot, and replacing them when they do.

One thing all these cheap ideas don't get round is the cost of immunising the signalling, and that costs big money.

The report suggests testing for every five to ten years, similar to that which occurs all over the country all the time for telephone poles, of course if you just went for the composite poles straight away you have about as much inspections as you do for metal supports.

I also note that the figures I have been quoting include signalling and telecomms immunisation, not that many lightly used lines have hyper advanced signalling in the first place.

As for the structural gauge issue, these lines could probably do with partial relaying as it is, so you might just be able to move one track the few inches required to allow the post to fit between the track, and arent former GWR lines like the Atlantic Coast Line build with the tracks further apart anyway?
Or the posts are sufficiently cheap that you could just plonk a post on each side and fit headspan assemblies or a wooden gantry, would be useful in stations methinks.

 

[Noguidedbus]

Well this "hybrid" OHLE design has apparently survived winter storms at wherever it was It was erected (I cant remember now :\ ) and we have trolleypole wiring all over the place these days so that doesn't seem to be much of a problem.

Take a look at what Blackpool's tramway has coped with over the last century.

That might well be true if the power could be obtained from regenerative sources locally; then perhaps they could have a genuinely carbon-neutral, with power produced locally. But if they're just going to take it from the regular National Grid, that'll just mean more electricity used, and therefore more Carbon produced in generating it. The idea of a self-contained local carbon-neutral demonstration installation might be worth pursuing, though; it could go withn the idea of 'micro-franchising' these branches and running them on a purely community basis. Just as long as that doesn't completely isolate them form the national network.

Hinkley C! Perfect.

 

[IanXC]

Unfortunately probably not low enough to appease the Harrogate Chamber of Commerce people (£30 million for electrification of the full 62km route and ~£150 million for 30 new five car Electric multiple units would bring it to £180 million, more than the £150 million they budget for the 'District Line to Harrogate' plan, but far more capable ).... but there might be some other people who could afford that.

I don't think Harrogate Chamber of Commerce had even suggested a finance source.

And they certainly have made no mention of how their project would overcome signalling interference at York and Leeds.

Might cause interference to the Signaller's tele?

So we should add a Sky subscription for each Signal Box?

 

[Nym]

So we should add a Sky subscription for each Signal Box?

Would be better to be Sky Plus, so he can pause, set his routes, then return to the tele...