Bi-mode Trains

[RichmondCommu]

G'day,

Given that we will need to start replacing DMU's in the next 10 - 15 years perhaps we should follow SNCF's approach and order some Bi-modes? These would be ideal for many routes where full electriification is at the moment only a dream and could easily be converted to EMU's in the future.

Surely this would make sense for the S&C, transpennine routes via the Hope Valley, the Buxton branch, Derby to Matlock, Derby to Crewe etc. Not only that but we wouldn't have to worry about introducing new services operated by DMU's.

Your thoughts would be very welcome!

Richmond Commuter!

 

[anthony263]

Perhaps you may have a point, Bi-mode in my opinion is ok for local/regional services but not for Intercity.

I have stated in others threads about a bi-mode version of the turbostar although Bombardier may have to do some redesigning of the turbostar design.

That said the minimum length of a bi-mode unit would be 3 carriages and can some local routes justify a train of that length?

 

[RichmondCommu]

That said the minimum length of a bi-mode unit would be 3 carriages and can some local routes justify a train of that length?

Given that the railways are projected to get increasingly busier I would say so. Given what we now know surely the 153's would never have been built? The possibilities are endless and the design is proven so I don't see why there would be any barriers.

 

[sprinterguy]

I have stated in others threads about a bi-mode version of the turbostar although Bombardier may have to do some redesigning of the turbostar design.

It'd be more of a Turbostar/Electrostar mish-mash: Diesel-electric drive and diesel engines, as opposed to the mechanical transmission that the Turbostars have.

 

[RichmondCommu]

It'd be more of a Turbostar/Electrostar mish-mash: Diesel-electric drive and diesel engines, as opposed to the mechanical transmission that the Turbostars have.

Please forgive my ignorance but would this be similar to the transmission used by Voyagers?

 

[Dave1987]

I was talking to one our siemens engineers recently about our 360's. The TS coach which has practically nothing under it is where the diesel engine would be located if it was not an EMU or at least thats what I gathered that he was saying I maybe wrong. They are also capable of having 3rd rail shoes fitted. Recently there was an idea put forward to have trains heading for Swansea and Cardiff to be under the wires for so long then fire up the engine for the rest of the way. I actually thought loco hauled would be ideal for this having an electric loco one end and a diesel loco the other.

 

[RichmondCommu]

Recently there was an idea put forward to have trains heading for Swansea and Cardiff to be under the wires for so long then fire up the engine for the rest of the way. I actually thought loco hauled would be ideal for this having an electric loco one end and a diesel loco the other.

The thing is a Bi-mode would be much quicker off the blocks than a loco hauled train. Given the routes that I propose for possible Bi-modes acceleration is everything. Not only that but you will end up dragging a 'dead' diesel loco for at times considerable distances.

 

[sprinterguy]

Please forgive my ignorance but would this be similar to the transmission used by Voyagers?

Yes, you are correct. The Voyagers have diesel-electric transmission.
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The thing is a Bi-mode would be much quicker off the blocks than a loco hauled train.

But not necessarily quicker at accelerating while working on diesel power than the existing DMUs with mechanical transmission. Additionally, a Bi-mode DMU would be slower to accelerate on electric power than a straight Electric Multiple Unit due to the additional weight of carrying both a transformer and diesel engines.

Though I am unable to give a technical appraisal of the reasons why mechanical transmission is favoured over diesel-electric drive for suburban and commuter DMUs, there must be a good reason why mechanical transmission has been the standard design for virtually every suburban and commuter diesel multiple unit that has been introduced in the UK, right up the most recent designs. I know that historically, particularly at the time of the Modernisation Plan in the 1950s and 60s, that utilising diesel-electric drive resulted in a much heavier railway vehicle than compared to the equivalent power output being transferred through a mechanical or hydraulic transmission, but I am sure that advances have been made in this area.

In short, I am considerably less than convinced that a Bi-mode multiple unit for suburban or commuter service would offer any benefits over standard DMUs or EMUs beyond being able to make use of the OHLE where it is available. The Bi-mode units would be heavier, and would be more complex to maintain.

 

[Jatos]

Well, I can't see the preference for DEMU unless you what the ability to make it all electric later down the line.

Fact is, powering a electric engine with an onboard diesel generator introduces much inefficiency, both from the extra weight of the components and the energy loss in generating electricity from diesel, then powering a motor with it, when you compare it a solution where a diesel engine directly provides the traction for the train, its considerably less efficient.

 

[pemma]

That said the minimum length of a bi-mode unit would be 3 carriages and can some local routes justify a train of that length?

There's plenty of 2 car DMUs around even ignoring the Pacers and 150s, so 3 car DEMUs could replace the likes of 2 car 17xs leaving the 2 car 17xs available to cascade to other routes.

A question I'd have about a DEMU with a pantograph is there a minimum length of OHE it would need to run under to justify putting up the pantograph?

 

[LexyBoy]

I'm also interested to know the advantage of mechanical transmission in units, when electric is favoured in locos. I can only imagine it's to do with the ease of scaling each system, and possibly the fact that a unit is not going to need the torque required by a loco, since each coach is only propelling itself.

Perhaps having each coach equipped with one diesel-mechanical powered bogie and one electrically driven could work, inelegant as it seems? Or say 2 diesel coaches and one electric in a 3-car unit.

 

[jopsuk]

The french bimodes are stunningly heavy, with average axle loads higher than 185s.

To give you an idea of how heavy we're talking, a "four car" AGC bimode is as long as a 185, is 30 tonnes heavier and has two less axles. Anything like that would have adverse speed restrictions even compared to a 185 and huge track access charges.

 

[RichmondCommu]

In short, I am considerably less than convinced that a Bi-mode multiple unit for suburban or commuter service would offer any benefits over standard DMUs or EMUs beyond being able to make use of the OHLE where it is available. The Bi-mode units would be heavier, and would be more complex to maintain.

Well the whole point of my suggestion is to take advantage of OHLE where ever possible i.e. transpennine trains running through the Hope Valley from say Norwich to Liverpool. Alsthom have built some for the SNCF so they have experience in maintaining them. I'll admit that the units are likely to be on the heavy side but these are the kind of lines which already carry freight so there shouldn't really be any weight restrictions.

In all fairness most suburban routes are either electrified throughout their length or does not use OHLE at any point on-route. It's the kind of routes already listed where these trains would be useful.

 

[sprinterguy]

Well the whole point of my suggestion is to take advantage of OHLE where ever possible i.e. transpennine trains running through the Hope Valley from say Norwich to Liverpool.

I presume then that "acceleration is everything" is no longer the case though?

I'll admit that the units are likely to be on the heavy side but these are the kind of lines which already carry freight so there shouldn't really be any weight restrictions.

Neither Matlock to Derby nor Derby to Crewe see much in the way of freight traffic. The track access charges for such heavy trains are likely to be prohibitively high for routes like this that are quite rural in nature for the most part, and will increase track maintenance costs.

 

[HSTEd]

Bi-mode seems to be weakening in case terms for me, considering the cost of simply electrifying all main line track miles in the UK only seems to come to around £22.5bn, (20,000 track miles total with about 15,000 miles unelectrified).

When you consider life cycle costs of some of these solutions the Swiss solution starts to look rather attractive.

 

[starrymarkb]

Alsthom have built some for the SNCF so they have experience in maintaining them.

Bombardier (first major SNCF order to go to a Non French company)

 

[RichmondCommu]

Bi-mode seems to be weakening in case terms for me, considering the cost of simply electrifying all main line track miles in the UK only seems to come to around £22.5bn, (20,000 track miles total with about 15,000 miles unelectrified).

When you consider life cycle costs of some of these solutions the Swiss solution starts to look rather attractive.

Yes but its going to be many years before all main line track is electrified and the railway will need interim solutions. Sooner or later we will need to purchase a large number of DMU's and Bi-mode would allow us to take advantage of partial electrified routes.

 

[jopsuk]

only if you accept much slower trains and much more maintainence to fix the damage caused by heavy trains. Unless you can magic much, much lighter bi-modes than those French AGCs into existence.

 

[HSTEd]

Yes but its going to be many years before all main line track is electrified and the railway will need interim solutions. Sooner or later we will need to purchase a large number of DMU's and Bi-mode would allow us to take advantage of partial electrified routes.

It would be easier to pay the premium necessary to assemble a second wiring train and crew, and possibly even a third one.
The capital cost of the trains themselves is only around ~£30m each.

That would allow us to have an entirely electric railway by ~2030, and if the correct order-of-electrification is chosen, would enable the existing diesel units to prove sufficient even as they withdrawn at life expiry.

(We can essentially add another several hundred track miles to the CP5 figures if another train is ordered right now, which would eliminate huge numbers of multiple units)

 

[RichmondCommu]

I presume then that "acceleration is everything" is no longer the case though?

Compared to the lunacy of dragging a dead diesel around (see above post) then yes absolutely. Even more so when you consider that a 100 mph unit is sharing routes with trains capable of 125 mph.

Neither Matlock to Derby nor Derby to Crewe see much in the way of freight traffic. The track access charges for such heavy trains are likely to be prohibitively high for routes like this that are quite rural in nature for the most part, and will increase track maintenance costs.

Can I therefore assume that you are in agreement that routes such as the S & C and the Hope Valley would be suitable for Bi-mode trains? In all fairness when I started this thread I didn't realise how heavy the SNCF Bi-modes are but who's to say that a re-design couldn't keep the weight down?

I agree that the Matlock branch doesn't and never will carry freight but If the Windermere branch can cope with Class 185's I don't see why the Matlock branch couldn't take something similar.
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It would be easier to pay the premium necessary to assemble a second wiring train and crew, and possibly even a third one.
The capital cost of the trains themselves is only around ~£30m each.

That would allow us to have an entirely electric railway by ~2030, and if the correct order-of-electrification is chosen, would enable the existing diesel units to prove sufficient even as they withdrawn at life expiry.

(We can essentially add another several hundred track miles to the CP5 figures if another train is ordered right now, which would eliminate huge numbers of multiple units)

Oh look, I agree with you that would be the best way forward but you and I know that no Government is ever going to agree to that kind of investment. Even the Germans are placing orders for huge numbers of DMU's because they recognise that its not viable to electrify the entire network. I'm 46 and in my lifetime I would be surprised if routes such as the Carnforth - Settle junction route is electrified and there are many others. Indeed, I would bet against Penzance being electrified in the next 15 years.
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only if you accept much slower trains and much more maintainence to fix the damage caused by heavy trains. Unless you can magic much, much lighter bi-modes than those French AGCs into existence.

Why there's no reason why Bombardier and even Hitachi couldn't be approached and asked to come up with a lighter design; at least something that matches the weight of a Class 185.

 

[HSTEd]

Oh look, I agree with you that would be the best way forward but you and I know that no Government is ever going to agree to that kind of investment. Even the Germans are placing orders for huge numbers of DMU's because they recognise that its not viable to electrify the entire network. I'm 46 and in my lifetime I would be surprised if routes such as the Carnforth - Settle junction route is electrified and there are many others. Indeed, I would bet against Penzance being electrified in the next 15 years.

Well supposedly we have a government that is no longer shy of spending more now to spend less later, although some of there recent plans to sell off the family silver says otherwise.

As to the benefits, you would get a BCR above 1 probably if you use government financing for the full ~£18bn (for all currently unelectrified ~12000 track miles) and reuse any electric units available.

Also an order for hundred+ 6 car regional units.

As to the Germans, they have lots of lines with very low service levels compared to British ones, we don't have that many lines with less than one train per hour on them these days.

 

[sprinterguy]

Can I therefore assume that you are in agreement that routes such as the S & C and the Hope Valley would be suitable for Bi-mode trains?

No, I only agree that they see a heavy freight traffic. There is such a small proportion of the total Leeds to Carlisle route electrified, and that is ever likely to be electrified, that Bi-mode trains are unlikely to be feasible against utilising existing DMUs for the forseeable future (The greater part of the TPE class 185 fleet will be available for other uses by the end of the decade). If/once the MML is electrified, then Bi-mode trains might be a rational proposition for the Liverpool to Norwich services, but that's quite a long distance route, rather than being a suburban service.

 

[RichmondCommu]

If/once the MML is electrified, then Bi-mode trains might be a rational proposition for the Liverpool to Norwich services, but that's quite a long distance route, rather than being a suburban service.

Well I don't think anybody is doubting that the MML will not now be electrified and in all fairness I can't recall saying that Bi-modes should be used on suburban routes. And I think we could add routes to such places as Cleethorpes and Scarborough to the list. If they can take a Class 185 then perhaps they could take a reduced weight Bi-mode?

 

[sprinterguy]

Well I don't think anybody is doubting that the MML will not now be electrified

I am. These big electrification proposals come in waves once every thirty years, promise much and result in one "headline" long distance electrification project - In this case, the GWML. I don't believe that the Midland Mainline electrification has been fully signed off and funding approved yet.

 

[RichmondCommu]

I am. These big electrification proposals come in waves once every thirty years, promise much and result in one "headline" long distance electrification project - In this case, the GWML. I don't believe that the Midland Mainline electrification has been fully signed off and funding approved yet.

Ok, I'm not sure as to what kind of authority you are on the subject but this forum is all about opinions and thats what makes it so interesting. There will be a lot of very annoyed people in South Yorkshire and the East Midlands if it doesn't go ahead!

Incidentaly, when I referred to the Hope Valley as being suitable for Bi-mode use I should have perhaps stated that this included services between Liverpool and Norwich. And of course other services between Liverpool and Sheffield.

 

[DDB]

I think that the mood of the public/government has changed and that rail will continue to grow and further lines will be electrified but I don't think the rate will get much quicker than already proposed and will continue to concentrate on main lines for the foreseeable future. My guess is that once the MML is done they will fill in the gaps. Sheffield to York first followed by turning round and heading south from Derby through Birmingham to Bristol. The Chiltern line has got to be a strong candidate being relatively self contained and IIRC the last non electric route into London. It also serves some politically powerful areas.

However I think it will be a long long time before every branch and every route that goes across main lines will be done, if ever. I suspect we will run out of DMUs before they are finished but the ROSCOs will be even more reluctant than now to order new ones. Even if we don't run out of DMUs more and more secondary services will spend part but only part of their journey under the wires.

If short bimodes can be made to work they seem the logical answer. So can they be made to work?

Am I right in thinking that the practical lower limit is a three car unit as you can put sufficient transformers under one car to pull two diesel cars with their engines off but you will need at least two diesel cars to have enough spare power to pull a third electric car away from the wires?

As it is the high speed main lines that are being electrified and the secondary branches that would need the diesel power the trains could cope with a much lower performance in diesel mode.

Why are the French bimodes so heavy? Is it because they are diesel-electric drive and so require generators attached to their diesel engines? In which case using mechanical transmission for the diesel cars (with a suitable clutch so they can free wheel under the wires) seems a simple solution? Any reason this wouldn't work?

Am I right in thinking that under a dmu generally only one bogie per car is powered? Therefore the other bogie could be electric powered?

One potential problem I can see is that it might not be possible to work in multiple in electric mode except in an emergency as assuming you can't have two pantographs up that close together you wouldn't want to have a coupling between multiple units that had to transfer that level of power. (As opposed to cables running between cars in the same multiple unit which would only be disconnected/connected very very infrequently in a depot if you had to swap a car out.) However there are plenty or routes where 3 or 4 cars is all you would ever need so you could embrace their lack of easy multiple working and use full width cabs which I assume give better aerodynamics and driver comfort and visibility. They would have course still have couplings to allow them to rescue/be rescued by other trains.

If the entire network gets electrified you just remove the engines.

Is this possible and a good idea. If not, why not?

DDB

 

[Cliveblackpool]

I think priority should be given to extend the OHE to the end of the run. Eg Penzance etc.
To convert a train to bi mode would it be better to insert an extra coach with 2 electric motors. Optional a small generator for diesel mode if there are steep banks on the route.
Eg 2 car DMU becomes 3 car. A voyager insert 2 extra coaches. Any steep banks on the run the driver can start the diesel engine/s for assistance at pre determined places.
The most efficient (green) way for larger trains would be change the power unit at the end of the wires! Push pull train arrives at a designated platform. A transverse track allows the locos to swop (slide) over, recouple.
Same in reverse when it or another train comes in the opposite direction.
(A loco breakdown would cause a problem, unless there was a back up!)
Or it could be swapped over the conventional way!

 

[LE Greys]

Firstly, can we change the thread title to "Electro-Diesel Trains" as this is a UK forum (says the hidebound traditionalist).

Secondly, I may be a big supporter of ED locomotives, since they seem to provide a way to increase electric freight without the need for a lot of shunters. However, I'm not so sure about EDMUs, because the weight penalty is proportionately a lot greater for a fast, light train rather than a big, heavy train.

 

[apk55]

I can agree that there could be case for Bi Modes particularily for regional services. A pure electric transmision would be the way to go with an alternator fixed to the diesel engine, and using the electric transmision motors, this would lighter and simpler than the mechanical transmision as suggested above.

In most cases the performance on diesel could be considerably less than on electric, as the route in most cases would be slower for the diesel sections. The sort of services that I could see benifiting would be transpennine services going to places such as Scarbourgh and Middlesbourgh, also Manchester to Barrow.

 

[YorkshireBear]

TPE seems perfect for B-mode to me. Allowing them to divert as they do currently and continue to serve the peripherals after electrification.