Discussion on electrification and the Marlow branch

[snowball]

Do trams run on 25kv?

The Sheffield tram-trains will be capable of doing so.

 

[MarlowDonkey]

The Sheffield tram-trains will be capable of doing so.

http://en.wikipedia.org/wiki/British_Rail_Class_399

That does seem a plausible solution to the problem of a lack of 2 car electric units, not that any operator of London area commuter services is going to welcome having a handful of non-standard vehicles. The top speed is quoted as 68 mph which wouldn't be a problem on the Branch, but they wouldn't be let out on main lines very often.

 

[AM9]

The relatively small number of passengers using Marlow sounds like the tail wagging the dog. The Marlow spur connection at Bourne End is a kludge to get around the closure of the line to High Wycombe.
If continuation of the existing 2-car DMU service to Maidenhead isn't good enough, the passengers have the option of travelling to Bourne End (bus, car etc.) and getting a 4-car service that can wait for another 4 or 8 cars at Maidenhead and travel to Paddington, or they have the very frequent Crossrail with an almost 100% chance of a seat at Maidenhead, and for most of them a direct connection to most tube lines.

 

[evergreenadam]

There is a precedent for a two-car 25kV EMU, the class 309/1 which was introduced in 1962 and ran until the late '70s when they were converted to 3 then 4-car units.
Such a unit nowadays would have very limited application and would be expensive to provide and operate. Far better to use one of the few remaining DMUs to take passengers to the vastly improved services at Maindenhead.

Why was a two car emu thought to be required, out of interest? Obviously it didn't prove to be practical for long.

 

[BantamMenace]

Dublin's dart operates 2-car EMUs albeit their a wider gauge.

 

[Class 170101]

Don't think that they could build one that wouldn't fall foul of the emissions regs

How about a light rail car as seen on DLR, T&W Metro, Manchester or Sheffield Super Tram instead?

 

[SpacePhoenix]

It would be, using a simplistic analysis over a sufficiently short interval.
If you do a proper analysis over the sixty year life of the electrification equipment, the costs pile up rather alarmingly - unless you make idiotically generous estimations of future battery technology.

Trouble is that a new build of DMU with short enough coaches for the platform is probably not going to be viable or even possible, with the current and future emissions regs

 

[MarkyT]

Looking in detail at Bourne End, there is a 'points indicator' as it is described in the sectional appendix on the Marlow platform (1), plated as 'BE1'. This is to all intents and purposes a platform starting signal and it is sited almost exactly at the switch tips of the points which lead either to the Marlow or Maidenhead routes. Measuring on Google Earth, there is around 70m between the buffer face and the signal position. There's a DOO dispatch mirror about 20m closer to the buffer stop and a 2 car turbo at the buffers stands behind this, yet dispatch at Bourne End is actually accomplished by the guard, who is needed on board to operate the ground frame so I'm not convinced the mirror is actually used. The layout suggests there is definitely not quite enough room in the platform physically for a 3x23m car turbo train to fit with the driver being able to see BE1. However With some special 'sighting; measures such as a co-acting duplicate signal head lower down on the signal post pointing at the cab window, it might be possible to accept a lower than ideal 'stand back' distance of around 8 metres, in which case a 3x20m car train actually WOULD fit in platform 1 without any track alterations.

 

[MarlowDonkey]

Trouble is that a new build of DMU with short enough coaches for the platform is probably not going to be viable or even possible, with the current and future emissions regs

It's not the length of individual coaches that's the problem, as the current 165s are 23 metres. So it's the more general problem of whether new DMUs can be built. I did have one other thought. Could you build an electric locomotive the same size as a steam tank engine? You then run push pull with a couple of trailers. It's still a one-off solution, so no economies of scale.

 

[MarkyT]

Trouble is that a new build of DMU with short enough coaches for the platform is probably not going to be viable or even possible, with the current and future emissions regs

I think a 3 car Vivarail D-train conversion from ex LU D78 stock, at 54m, would fit easily in the 70m Marlow platform at Bourne End with a good 16m stand-back from the platform starting signal.

 

[muddythefish]

The Marlow branch sounds like the perfect place for Pacers no long required by Northern.

 

[MarkyT]

The Marlow branch sounds like the perfect place for Pacers no long required by Northern.

Well actually the nice clean FGW ones we have in Devon aren't that bad with fairly comfy seats and even a decent ride on welded track, but they're dreadfully noisy, especially the flange squeal on tight curves. Imagine that on the curve to Marlow at Bourne End!

 

[AM9]

Why was a two car emu thought to be required, out of interest? Obviously it didn't prove to be practical for long.

The 2-car version was needed to allow a better power to weight ratio on certain peak-hour trains, (up to 4512hp on a 12-car train, probably the most powerful in the UK at the time).
They were very successfully used on the GEML intensively between 1962 and the '80s (when they were replaced by 321s). I have never seen a single 2-car version (309/1) running alone, but I believe they did occasionally run on the Frinton/Walton branch when split from a 4-car unit.

Apologies to the OP for going OT.

 

[Dennis]

The Marlow branch sounds like the perfect place for Pacers no long required by Northern.

Given no other sensible solution seems to exist, a cheaper option would be to close the branch and replace the services with buses (just not Solos).

 

[Mikey C]

They should shut the line from Marlow and Bourne End... and replace it with a connecting boat service along the Thames

 

[MarkyT]

Given no other sensible solution seems to exist, a cheaper option would be to close the branch and replace the services with buses (just not Solos).

Well, the sensible shorter term option is to retain 2 car turbos on the branch whilst Reading depot has to retain a diesel allocation for other purposes (North Downs and Bedwyn). In the longer term investigate 3x20m car EMU options as I described up-thread.

 

[evergreenadam]

Well, the sensible shorter term option is to retain 2 car turbos on the branch whilst Reading depot has to retain a diesel allocation for other purposes (North Downs and Bedwyn). In the longer term investigate 3x20m car EMU options as I described up-thread.

With the through services to Paddington withdrawn and a half hourly shuttle between Marlow and Maidenhead throughout the day as facilitated by the funding mentioned earlier, all trains between Bourne End and Maidenhead will also be two coaches. Will that be enough capacity or is the extra capacity provided by the longer through trains to Paddington required on the branch itself during the peaks?

 

[MarkyT]

With the through services to Paddington withdrawn and a half hourly shuttle between Marlow and Maidenhead throughout the day as facilitated by the funding mentioned earlier, all trains between Bourne End and Maidenhead will also be two coaches. Will that be enough capacity or is the extra capacity provided by the longer through trains to Paddington required on the branch itself during the peaks?

I think the electrification as far as Bourne End would enable the through London trains to be run by a single 4x20m car EMU. A small problem with the scissors arrangement (drawing nearly ready!) is the new turnout is partway along platform 2. A sharp turnout here implies greater end-throw of a vehicle to or from Marlow, so platform edge coping stones would have to be cut back alongside the turnout to the extent that maximum stepping distance would be exceeded, meaning that only the first three carriage lengths from the buffer stop would be safely accessible. SDO technology can solve that problem by disabling the doors on the London end driving vehicle, . Any train used on these services would thus have to be equipped with through gangways within the 4 car unit, not a problem with the proposed GW electric fleet.
--- old post above --- --- new post below ---
Diagram of Bourne End Station with the additional track for enhanced service to Marlow.

http://www.townend.me/files/bourne-end2.pdf

 

[SpacePhoenix]

I don't know the line(s) what route(s) are there that serve Bourne End?

 

[MarlowDonkey]

Diagram of Bourne End Station with the additional track for enhanced service to Marlow.

What your diagram doesn't show is that platform 2 is currently longer than platform 1. The existing platform 1 goes as far as the current Marlow crossover and platform 2 stretches towards the crossover where the line singles on the way to Maidenhead.

Here's a picture of the junction from the "Turbo" era.

http://www.mmpa.org.uk/gallery/gallery1/p09.jpeg

 

[AM9]

I think the electrification as far as Bourne End would enable the through London trains to be run by a single 4x20m car EMU.

Sending a 4-car EMU into Paddington would be a waste of valuable paths. Unless Maidenhead is being remodelled to allow mainline access to the northernmost platform, any plan to attach the Bourne End EMU to another would block the up slows. Having one stand in platform 5 waiting would be a waste of an EMU.
So if the GWML is to be as busy as some here say the only solution would be to run an EMU shuttle from Maidenhead to Bourne End and a DMU shuttle from Bourne End to Marlow. With no reversing at Bourne End, a more frequent peak service could run on each leg of the journey and all passengers would benefit from a much more frequent service to London. It would even be possible to install a Penrhyn loop at Cookham to allow 2 train working, giving a longer turn-round at Bourne End to give Marlow passengers somewhere warm to sit.
Anything more complicated wouldn't be justified with such a small passenger flow.

 

[MarlowDonkey]

With no reversing at Bourne End, a more frequent peak service could run on each leg of the journey and all passengers would benefit from a much more frequent service to London.

That's the way it works at the moment in peak hours with a shuttle Maidenhead to Bourne End and Bourne End to Marlow. Timetables vary as to whether the train terminates at Maidenhead or continues to Paddington. In the evening it's necessary to get a train to Bourne End to form the second shuttle and that's often a through from Paddington. With some variations, the service has run that way since closure of the line to High Wycombe in 1970, if not before.

As to what the service pattern will be when the main line is electrified and 165s are only operating Maidenhead Marlow remains to be seen. Whilst direct access to Central London and the City is good for local commuters, it's not going to be so wonderful if the peak fasts and all day semi fasts are withdrawn in favour of an all stations Crossrail train.

The current off peak service pattern from Maidenhead is four trains per hour, all of which call at Slough, West Drayton, Hayes and Ealing Broadway. Some call additionally at a choice from Taplow, Burnham, Langley, Iver and Southall.

 

[Buttsy]

Surely the answer is to close Station Road and extend the Marlow platform towards Wycombe. There is an alternative route for traffic that shouldn't cause too much of an issue...

 

[dviner]

Surely the answer is to close Station Road and extend the Marlow platform towards Wycombe. There is an alternative route for traffic that shouldn't cause too much of an issue...

Not grand enough!

Demolish the existing station and the Auction Rooms, raise the height of the track bed, and curve it slightly south-east, with it going on stilts over Station Road (perhaps lower that a bit to give more headroom) - should give enough length to fit in a 5-car EMU and reduce the radius of the Marlow branch...

 

[MarkyT]

What your diagram doesn't show is that platform 2 is currently longer than platform 1. The existing platform 1 goes as far as the current Marlow crossover and platform 2 stretches towards the crossover where the line singles on the way to Maidenhead.

Here's a picture of the junction from the "Turbo" era.

http://www.mmpa.org.uk/gallery/gallery1/p09.jpeg

Thanks for the picture. I found lots of useful pictures on the passengers association website, including this one showing the signal on platform 1 in the snow: http://www.mmpa.org.uk/gallery/gallery6/p10.jpeg

I realise the existing platform 2 is longer today. I deliberately shortened it because of the new turnout (part of the 'scissors' arrangement), placed partway along platform 2. The problem is that if a turnout is partway along the platform, vehicles taking the tightly curved turnout to or from Marlow overhang significantly at their ends, so the edge of the platform would have to be cut back to take this into account. This would likely be to such an extent that the gap between platform edge and door at that location would become excessive and unsafe, so in any new construction that would have to be approved by the ORR, such an arrangement is unlikely to be acceptable. Hence, I have shown the platform in its final state cut back to the turnout. This is not necessarily a big problem for a four-car train as long as it has a SDO system that can automatically lock or enable doors on individual cars - i.e the three cars safely at the buffer stop end would have doors released whilst the outermost car, stopped over the turnout, would not.

The overhang of vehicles, on the outside of a curve in this case, is known as 'end throw', and together with it's counterpart 'centre throw' on the inside of a curve are the reasons why new platforms are not generally allowed either side of curves less than 300m or so in radius. Of course, there are existing places, notably on the tube, where platforms are on severe curves with significant gaps 'to mind', but these would never be permitted in new construction.

 

[Peter Mugridge]

Diagram of Bourne End Station with the additional track for enhanced service to Marlow.

http://www.townend.me/files/bourne-end2.pdf

That's almost exactly what I tried to suggest in post #32 but I couldn't get the attachment working properly.... The only difference is I didn't put in a scissors crossing but instead slightly shifted both branches on the approach in order to simply move the points slightly further out..

 

[Bletchleyite]

The overhang of vehicles, on the outside of a curve in this case, is known as 'end throw', and together with it's counterpart 'centre throw' on the inside of a curve are the reasons why new platforms are not generally allowed either side of curves less than 300m or so in radius. Of course, there are existing places, notably on the tube, where platforms are on severe curves with significant gaps 'to mind', but these would never be permitted in new construction.

Platform 17 at Clapham Jn is the largest chasm I've seen...wider I think even than Bank Central Line.

 

[MarkyT]

Sending a 4-car EMU into Paddington would be a waste of valuable paths. Unless Maidenhead is being remodelled to allow mainline access to the northernmost platform, any plan to attach the Bourne End EMU to another would block the up slows. Having one stand in platform 5 waiting would be a waste of an EMU.
So if the GWML is to be as busy as some here say the only solution would be to run an EMU shuttle from Maidenhead to Bourne End and a DMU shuttle from Bourne End to Marlow. With no reversing at Bourne End, a more frequent peak service could run on each leg of the journey and all passengers would benefit from a much more frequent service to London. It would even be possible to install a Penrhyn loop at Cookham to allow 2 train working, giving a longer turn-round at Bourne End to give Marlow passengers somewhere warm to sit.
Anything more complicated wouldn't be justified with such a small passenger flow.

The problem is Marlow passengers have got used to the through service to Maidenhead, so enforcing an additional change for short local journeys would be very unpopular, and might have unintended consequences on branch ridership especially leisure and off-peak during the day. The Henley and Bourne End direct London trains have always been difficult to justify from a capacity point of view, but politically they're impossible to curtail, at least today before Crossrail is established. Once that is up and running, I'm sure a single change a Maidenhead for a range of Central London destinations will be just as attractive as the though train to Paddington, where most passengers change for onward travel.

 

[MarkyT]

That's almost exactly what I tried to suggest in post #32 but I couldn't get the attachment working properly.... The only difference is I didn't put in a scissors crossing but instead slightly shifted both branches on the approach in order to simply move the points slightly further out..

Yes I saw that Peter - the attachment was there in the post to download and view in a word processor, but the forum is unable to directly view .doc files.

I've attached my screen grab of your file, which was the inspiration to try something of my own, thank you! I also first started working on the basis of moving the junction further out, but came to the conclusion that the already tight curve from the Marlow line would be made even worse, and on further investigation I found there was in fact sufficient room for a 3x20m car train in platform 1 so the curves could be left broadly as they are.

 

[Peter Mugridge]

Yes I saw that Peter - the attachment was there in the post to download and view in a word processor, but the forum is unable to directly view .doc files.

I've attached my screen grab of your file, which was the inspiration to try something of my own, thank you! I also first started working on the basis of moving the junction further out, but came to the conclusion that the already tight curve from the Marlow line would be made even worse, and on further investigation I found there was in fact sufficient room for a 3x20m car train in platform 1 so the curves could be left broadly as they are.

That's great thanks - yes, it shows OK now - I just couldn't convert the file to a .jpg myself for some reason.

Yes, you can just about fit a 3 x 20m unit ( 313 anyone?! ) in there although the margins are very tight - I suggested moving the point and curves with the idea of getting a 4 x 23m unit in it to allow a standard fleet.