Ideas for cascading ScotRail DMUs following introduction of new EMU/BEMU stock

[snookertam]

I'm still confused why Rail batteries are so poor compared to Coach

Because trains are much, much heavier than buses, and are quite different technology.

As for the wider discussion, battery powered trains in the west highlands seem a long way off unless we’re prepared to have multiple charging points through the route. Don’t fancy risking running out of charge in the middle of Rannoch Moor.

 

[Altnabreac]

The expensive bit is new grid connections so you’d minimise those if converting to battery by extending the wires north from Craigendoran. Maybe as far as Crianlarich?

The terminal dwell times are quite doable for plug in charging at Oban and Mallaig so they make sense.

You’d then only need a short section around Fort William with a new grid connection there. Probably either FW - Spean Bridge or maybe Tulloch.

Either way there is a good ten years of more productive wiring before this comes to pass. Decarbonisation target completion is 2045 so Longer range BEMUs for Stranraer, WHL and FNL will not be ordered in next 10 years while still meeting that target.

 

[BlueLeanie]

Because trains are much, much heavier than buses, and are quite different technology.

As for the wider discussion, battery powered trains in the west highlands seem a long way off unless we’re prepared to have multiple charging points through the route. Don’t fancy risking running out of charge in the middle of Rannoch Moor.

No that doesn't explain anything.

An Ember coach weighs 21 tonnes, a class 156 coach weighs 38 tonnes. That's 1.5 tonnes per metre for a the road coach, and 1.65 tonnes per metre for a rail coach - not a vast difference.

Technology wise, steel on steel is far more efficient than rubber on tarmac, but either way it's a engine/motor driving wheels. Regenerative braking is regenerative braking whether it's on a train or on a coach.

I also really don't understand this fear of running out of battery on Rannoch Moor. Why is this going to happen?

So you leave Fort Bill on the first train of the day. It's a four coach unit, fully charged with 1MWh of battery under each coach. One hour, or 60km later on Rannoch Moor the batteries are empty. The coach with half this capacity is still tanking down towards Crianlarich with enough power to take it to Edinburgh.

It doesn't make sense.

 

[AlastairFraser]

I also really don't understand this fear of running out of battery on Rannoch Moor. Why is this going to happen?

So you leave Fort Bill on the first train of the day. It's a four coach unit, fully charged with 1MWh of battery under each coach. One hour, or 60km later on Rannoch Moor the batteries are empty. The coach with half this capacity is still tanking down towards Crianlarich with enough power to take it to Edinburgh.

It doesn't make sense.

This is in the scenario of a severe weather event on Rannoch Moor (or frankly numerous other vulnerable points along the line).
Evacuation of people onboard to a safe location could take hours - will the battery withstand that?

 

[BlueLeanie]

This is in the scenario of a severe weather event on Rannoch Moor (or frankly numerous other vulnerable points along the line).
Evacuation of people onboard to a safe location could take hours - will the battery withstand that?

Well, let's do the arithmetic (again)

You have 1000kWh in each coach battery as it leaves Fort William station.

After 60 minutes running a 250kW motor at maximum power (I've no idea if the current 156s are on full throttle for the full 60 minutes leaving Fort William or not, I'm sure someone will confirm), the train comes to a stop.

How many kWh do you have remaining?

If the heat pump operates at 5kWh and the remaining services use 2kWh.

How many hours will it be before the battery is exhausted?

I strongly suspect that the lavatory tanks will have reached capacity long before the batteries run out.

 

[N1]

This is in the scenario of a severe weather event on Rannoch Moor (or frankly numerous other vulnerable points along the line).
Evacuation of people onboard to a safe location could take hours - will the battery withstand that?

Rhätische Bahn are quite happy operating pure EMUs over Bernina Pass and other worse conditions than Rannoch, no huge battery back-up or diesel engines. There are bigger risks in south England from ice build up on top of conductor rail, than being trapped on West Highland line.

 

[AlastairFraser]

Rhätische Bahn are quite happy operating pure EMUs over Bernina Pass and other worse conditions than Rannoch, no huge battery back-up or diesel engines. There are bigger risks in south England from ice build up on top of conductor rail, than being trapped on West Highland line.

That's partly because they are pure EMUs (so only a very small risk of losing power if you maintain it regularly and build preventative measures like avalanche shelters), and partly because Switzerland is a country that takes a rather radical approach to continuity of public transport (so they will stop at nothing to evacuate quickly and safety - Network Rail seems to be content with leaving people on trains for hours in poor conditions as you allude to, with your comment about 3rd rail ice build-up issues).

They even had a rail replacement helicopter for a funicular once: https://aviation.direct/en/braunwal...ersatzfluege-mit-helikoptern-fuer-720-franken

 

[stevieinselby]

An Ember coach weighs 21 tonnes, a class 156 coach weighs 38 tonnes. That's 1.5 tonnes per metre for a the road coach, and 1.65 tonnes per metre for a rail coach - not a vast difference.

The reason an Ember coach weighs 21 tonnes is because it's got a honking big battery in it. A regular diesel coach weighs significantly less, and that's the comparison you need to make.

 

[tbtc]

AFAICS the WHL uses the same 156s that short urban routes like the East Kilbride branch has

We didn't specify special diesel trains for West Highland services with extra big fuel tanks, just in case a service is trapped on Rannoch Moor

(same with 158/170s on Inverness services being the same trains that run Fife 'circles')

Insisting on a bespoke microfleet, custom designed for the handful of WHL services probably appeals to the kind of Blue Sky Thinkers who have a wishlist of things like observation cars but pushing those specific (and clearly identifiable) costs onto these services seems... brave!

Pure DMUs like 195s ought to last well into the 2050s (and be cascaded down from their current services in good time), so I wouldn't worry about designing special trains for the WHL, I'd focus more on how to manage its summer capacity without wastefully dumping lots of stock in sidings for six months of the year

 

[Bletchleyite]

Insisting on a bespoke microfleet, custom designed for the handful of WHL services probably appeals to the kind of Blue Sky Thinkers who have a wishlist of things like observation cars but pushing those specific (and clearly identifiable) costs onto these services seems... brave!

Pure DMUs like 195s ought to last well into the 2050s (and be cascaded down from their current services in good time), so I wouldn't worry about designing special trains for the WHL, I'd focus more on how to manage its summer capacity without wastefully dumping lots of stock in sidings for six months of the year

In any case we already have DMUs which are as good as panoramic - 170s. Doing whatever work is required to clear those (which would also clear most other DMUs for the future) is a good bet. Though aside from the 196 the Civities also have nice big windows.

 

[Trainbike46]

AFAICS the WHL uses the same 156s that short urban routes like the East Kilbride branch has

We didn't specify special diesel trains for West Highland services with extra big fuel tanks, just in case a service is trapped on Rannoch Moor

(same with 158/170s on Inverness services being the same trains that run Fife 'circles')

Insisting on a bespoke microfleet, custom designed for the handful of WHL services probably appeals to the kind of Blue Sky Thinkers who have a wishlist of things like observation cars but pushing those specific (and clearly identifiable) costs onto these services seems... brave!

The short term solution is simply to use the DMUs freed up from central belt services, which may well be the 170s, which have many years of life left in them.

Pure DMUs like 195s ought to last well into the 2050s (and be cascaded down from their current services in good time), so I wouldn't worry about designing special trains for the WHL, I'd focus more on how to manage its summer capacity without wastefully dumping lots of stock in sidings for six months of the year

This one is relatively easy - during the vacations (which is when demand on the Scottish rural lines will be highest), many other lines will have lower commuting demand - so use trains from other areas. I'm assuming that is what Scotrail already does, but maybe the units will have to come from slightly further in the future (e.g. Northern)

 

[BlueLeanie]

The reason an Ember coach weighs 21 tonnes is because it's got a honking big battery in it. A regular diesel coach weighs significantly less, and that's the comparison you need to make.

It does indeed, but here's a little secret. A modern compliant diesel engine isnt light, neither is an exhaust system and the other bits needed to operate.

100 litres of diesel weighs around 90kg, and once you've burnt each litre of diesel it's gone for good, whereas there's lots of potential energy to recover on the 400 metre drop in elevation from Corrour back to sea level to replenish that honking big battery.

 

[Bletchleyite]

This one is relatively easy - during the vacations (which is when demand on the Scottish rural lines will be highest), many other lines will have lower commuting demand - so use trains from other areas. I'm assuming that is what Scotrail already does, but maybe the units will have to come from slightly further in the future (e.g. Northern)

Northern's 170s are extremely unsuitable for what they do, spending all their time churning up transmission oil on local services, so if enough of whatever they're ordering could replace them they could I guess go (back?) to Scotland...

 

[BerkshireRails]

Why are we using the class 156 to reference how much power a unit requires for the West Highland Line? When wouldn't it be better to use something like a new class 197, which has more comforts that passengers would expect in new trains, like Air Con? Just because the class 156s work the line doesn't mean power requirements won't be greater on new stock.

If rail batteries need more range between charging points, it's best to just use a range extender diesel generator while stopped at stations, which is also useful in an emergency

I don't see keeping residual diesel traction as a range extender as an attractive option for the Scottish government, which is why I think it will use fast chargers.

The reason an Ember coach weighs 21 tonnes is because it's got a honking big battery in it. A regular diesel coach weighs significantly less, and that's the comparison you need to make.

Just for class 230, there is a 400kg difference between the generator and battery rafts. 2.9 x 0.9 x 0.9 metres = 2.349 Cubic Metres of diesel in the fuel tank on a class 230.

The diesel generator set was designed to fit within a standard raft of 2.9 x 0.9 x 0.9 metres with a common mechanical interface. It has a 110 kW Ford 3.2 litre engine, compliant to EU stage IIIB emission standards, which is coupled to an axial-flux three-phase alternator. The generator raft weighs 1.3 tonnes and the diesel-powered Class 230 units have two engine rafts under each driving motor coach.

Similarly, the protype battery train, 230002, has two battery rafts under each motor coach. This was built to test the concept of battery operation, rather than for a specific order, and initially used batteries from the 2015 Independently Powered EMU (IPEMU) trial.

The units are configured for up to three rafts per motor car and five rafts per trailer car. On diesel units, the fuel tank, which supplies two engine modules, takes up the space of one raft.

The generator and battery rafts weigh 1.3 and 1.7 tonnes respectively. An assessment of the vehicles’ dynamics confirmed that this extra weight was not a problem, given that the repurposed units will not experience the Underground’s crush loading.

 

[BlueLeanie]

This one is relatively easy - during the vacations (which is when demand on the Scottish rural lines will be highest), many other lines will have lower commuting demand - so use trains from other areas. I'm assuming that is what Scotrail already does, but maybe the units will have to come from slightly further in the future (e.g. Northern)

Not quite...

Scotland's school holidays often differ from England.

For example, the April holiday is generally now fixed to the first two weeks in April. There's no May half term, summer holidays start in June, and return early August. Tatty is the second Monday in October for two weeks.

But probably most important of all, the Edinburgh Fringe - that's a solid 4 weeks of business at the same time as the rural lines are busy.

 

[AlastairFraser]

AFAICS the WHL uses the same 156s that short urban routes like the East Kilbride branch has

We didn't specify special diesel trains for West Highland services with extra big fuel tanks, just in case a service is trapped on Rannoch Moor

(same with 158/170s on Inverness services being the same trains that run Fife 'circles')

Insisting on a bespoke microfleet, custom designed for the handful of WHL services probably appeals to the kind of Blue Sky Thinkers who have a wishlist of things like observation cars but pushing those specific (and clearly identifiable) costs onto these services seems... brave!

Pure DMUs like 195s ought to last well into the 2050s (and be cascaded down from their current services in good time), so I wouldn't worry about designing special trains for the WHL, I'd focus more on how to manage its summer capacity without wastefully dumping lots of stock in sidings for six months of the year

It's not really a bespoke microfleet type situation, it's a fleet for the long rural Scotrail lines that have absolutely no prospect of full electrification - so the West Highland, Kyle of Lochalsh and Far North lines fit the bill.
Something like a hydrogen/battery/OHLE tri mode would make sense once all the DMUs have reached the end of their reasonable service life, but this forum seems to be fixated on pure battery units for every line now (which are great for short and medium distance unelectrified lines, but I'm not sure they are particularly suitable for the 3 lines I mentioned by 2040.)

 

[Brubulus]

It's not really a bespoke microfleet type situation, it's a fleet for the long rural Scotrail lines that have absolutely no prospect of full electrification - so the West Highland, Kyle of Lochalsh and Far North lines fit the bill.
Something like a hydrogen/battery/OHLE tri mode would make sense once all the DMUs have reached the end of their reasonable service life, but this forum seems to be fixated on pure battery units for every line now (which are great for short and medium distance unelectrified lines, but I'm not sure they are particularly suitable for the 3 lines I mentioned by 2040.)

I can see how the West Highland could deserve "intercity" battery units. I think ScotRail would do well with a fleet of 120M BEMU units for intercity work, with First Class. Alongside that, a fleet of short 40M units that can be used to supplement capacity and work to Oban, Carlisle, Kyle, Far North, Aberdeen-Inverness and other regional routes outside the Central Belt, while the newly ordered BEMUs can do Central Belt work. Basically a fleet of BEMU 444s and short 2 car units.

 

[AlastairFraser]

I can see how the West Highland could deserve "intercity" battery units. I think ScotRail would do well with a fleet of 120M BEMU units for intercity work, with First Class. Alongside that, a fleet of short 40M units that can be used to supplement capacity and work to Oban, Carlisle, Kyle, Far North, Aberdeen-Inverness and other regional routes outside the Central Belt, while the newly ordered BEMUs can do Central Belt work. Basically a fleet of BEMU 444s and short 2 car units.

I doubt Scotrail will go for pure BEMUs for anything outside the Central Belt, they'd more likely continue the focus on discontinuous electrification and order bi mode OHLE/battery BEMUs for the Intercity services, but only post 2040 for an intercity replacement (given that the 222s are the next Intercity fleet I believe).

 

[Brubulus]

I doubt Scotrail will go for pure BEMUs for anything outside the Central Belt, they'd more likely continue the focus on discontinuous electrification and order bi mode OHLE/battery BEMUs for the Intercity services, but only post 2040 for an intercity replacement (given that the 222s are the next Intercity fleet I believe).

I believed the 222s were a medium term solution to get rid of the HSTs, not the long term plan for Scottish intercity rail. When I say BEMU, I am referring to OHLE/battery units, trying to make clear that they won't have a diesel engine since it's unnecessary, even on a line as long as the WHL or Far North line due to the low speeds and potential for partial electrification/fast chargers.

I can see the Southern 171s going to ScotRail, but not the Northern 170s, since hopefully Northern goes for Battery/OHLE trains and will need all the diesel units they can for the medium term, while Southern could (by comparison) replace their diesel units with battery trains. But given the relatively short stay of the 171s in Scotland, it might just be that the 158s which are in the best condition would stay for a 45 year lifespan. I suspect that the 170s and 222s will be replaced around 2035, completing the decarbonisation of ScotRail.

 

[AlastairFraser]

I believed the 222s were a medium term solution to get rid of the HSTs, not the long term plan for Scottish intercity rail.

Yes, but other fleets will probably be prioritised for replacement pre-2040, given the tightening of the Scottish budget.

When I say BEMU, I am referring to OHLE/battery units, trying to make clear that they won't have a diesel engine since it's unnecessary, even on a line as long as the WHL or Far North line due to the low speeds and potential for partial electrification/fast chargers.

I agree no diesel, it's incompatible with Scotrail's decarbonisation plans.
Hydrogen is more capable of operating the Far North/West Highland/Kyle of Lochalsh lines IMHO.

I can see the Southern 171s going to ScotRail, but not the Northern 170s, since hopefully Northern goes for Battery/OHLE trains and will need all the diesel units they can for the medium term, while Southern could (by comparison) replace their diesel units with battery trains.

I thought Northern were planning to replace and/or cascade everything but the 195/331s, so the 170s may well end up with Scotrail or EMR.

But given the relatively short stay of the 171s in Scotland, it might just be that the 158s which are in the best condition would stay for a 45 year lifespan.

I think all of the Turbostar family will last longer than the Express Sprinter 158/159 classes, they are beginning to show their age and they are slower than the 170/171/172 classes. There's also the aspiration to simplify maintenance, and keeping the 158s longer than 2032-2035 when 170/171s are potentially on offer would run counter to the general maintenance simplification trend.

I suspect that the 170s and 222s will be replaced around 2035, completing the decarbonisation of ScotRail.

I don't think Scotrail (or Transport Scotland) will be able to afford to completely decarbonise by 2035, especially with the continued investment in reopenings and extension of electrification.

 

[HighlandStorm]

Anyone thinking 170s are the answer to anything on the West Highland Line need to give their head a wobble and then ask a different question.

 

[GlitterUnicorn]

I agree no diesel, it's incompatible with Scotrail's decarbonisation plans.
Hydrogen is more capable of operating the Far North/West Highland/Kyle of Lochalsh lines IMHO.

I’d take that as an indication that the decarbonisation plans are unrealistic.

To support some rural lines which are already heavily subsidised, while maintaining their decarbonisation plan, an already stretched incredibly thin Scottish Government would have to spend a massively disproportionate amount on either first of their kind hydrogen trains, over the top electrical grid connections to remote locations to support BEMUs, or some other over the top solution.

Common sense would suggest that they settle for almost-decarbonisation and tolerate a small fraction of services to remain operated by Diesel for the foreseeable…

 

[AlastairFraser]

Anyone thinking 170s are the answer to anything on the West Highland Line need to give their head a wobble and then ask a different question.

Hahaha why? They operate longer regional routes elsewhere in the UK.

I’d take that as an indication that the decarbonisation plans are unrealistic.

To support some rural lines which are already heavily subsidised, while maintaining their decarbonisation plan, an already stretched incredibly thin Scottish Government would have to spend a massively disproportionate amount on either first of their kind hydrogen trains, over the top electrical grid connections to remote locations to support BEMUs, or some other over the top solution.

Common sense would suggest that they settle for almost-decarbonisation and tolerate a small fraction of services to remain operated by Diesel for the foreseeable…

Well I don't think they'd have to order new trains on the WHL/Far North/Kyle of Lochalsh until 2040-2045, so it's not a case of pushing the budget even further now.
They wouldn't exactly be first of their kind either - there is a suitable model on the market and, in fact, in operation right now, so in 20 years time, the technology will have had significant time to mature.

 

[David M]

Czech railways have some new dual electric and battery Panters - I don't know their range but assume quite a distance is outwith wires.
I assume they're too tall for our loading gauge.

 

[Snow1964]

A tender transparency notice has been published for Scotrail 170s, lease was due to end 31 March 2030, but has been extended 10 years, with optional extra 2 years.

So looks like keeping 170s into 2040s

2 buyers​

• Scotrail Trains Glasgow

1 supplier​

• Porterbrook London

Description​

This notice concerns a modification to an existing lease (the Lease) procured whilst ScotRail was under the Abellio franchise ownership, between ScotRail Trains Limited (SRT) and Porterbrook Leasing Company Limited (Porterbrook) for 102 Class 170 vehicles (the Fleet). The Lease is currently scheduled to expire on 31 March 2030 and a 10-year extension has been agreed to the Lease for the same scope of supplies, with an additional option to extend for up to a further 2 years. The value of that extension (inclusive of options) is GBP 265,700,000 excluding VAT. This extension is necessary to ensure SRT is able to discharge its obligations and continue to deliver vital services while the suburban and rural new fleet procurements are commenced and is therefore an interim solution until the new fleet can be procured, built and commissioned for passenger service. An interior refurbishment will be undertaken to the Fleet to ensure it can continue to operate for passenger service for the duration of the extension.

Total Quantity or Scope​

The Lease is being modified in accordance with regulation 86(1)(b) of the Utilities Contracts (Scotland) Regulations 2016 as additional supplies not included within the original procurement have become necessary, and a change of contractor cannot be made for economic or technical reasons and would cause significant inconvenience or substantial duplication of cost for SRT, because:
1. The modification has become necessary: there is a need to secure the ongoing operation of the Lease, which includes lifeline services in rural and east suburban areas, while SRT carries out a full procurement for an enduring rolling stock solution using emerging technologies (including batteries and network electrification). Diesel trains are the only feasible option for this interim period.

2. A change of contractor cannot be made for economic or technical reasons: this is because:
a. the Fleet has specific characteristics and technical features that are designed to interoperate with the rail infrastructure and SRT’s other fleets and are required for operation on the East Suburban Lines. For example:
i. the Fleet is the only available DMU passenger stock which is fully accepted for operation on these lines and is able to make use of differential speed limits to meet the required journey times;
ii. the Fleet has been fitted with Variable Rate Sanding Equipment, funded by the Scottish Targeted Performance Fund, to offer improved braking performance in low adhesion environments and support SRT’s safety case;
iii. the Fleet is able to maintain technical compatibility with the network (including the CL158 fleet with which it is required to operate interchangeably) and depots, ensuring SRT satisfies the operational requirements stipulated in its Grant Agreement with Scottish Ministers.
iv. any alternative Fleet would require an extensive programme of train crew and engineering staff training, incurring significant training which would create significant additional (and disproportionate) training workload at a time when SRT is already engaged in an intensive programme of recruitment for future fleet cascades and new trains;
v. Please note there is a Section 54 Agreement currently in place until 2035. An extension to the Section 54 agreement is being finalised in relation to the Fleet, and SRT expects that agreement to be in place for the full duration of the lease and options.
b. SRT’s analysis has confirmed that there are no alternative available fleets (other than the CL158s that SRT already operates) that contain the necessary technical features and could meet these requirements. In the event that an alternative existing fleet with suitable performance and technical characteristics was available (which in SRT’s view is not the case), and that fleet could be adapted to accommodate the necessary technical features, this would result in substantial duplication of cost, significant inconvenience and extra time out of service, which would be disproportionate in the context of an interim solution

https://bidstats.uk/tenders/2026/W03/862716391

 

[AlastairFraser]

A tender transparency notice has been published for Scotrail 170s, lease was due to end 31 March 2030, but has been extended 10 years, with optional extra 2 years.

So looks like keeping 170s into 2040s

https://bidstats.uk/tenders/2026/W03/862716391

Makes sense that they would be the last DMUs to go. They are probably the newest regional DMU they own and I believe someone else has mentioned on this thread that the Far North/Kyle of Lochalsh/West Highland Lines decarbonisation plan has been delayed due to funding shortages.

 

[43096]

Makes sense that they would be the last DMUs to go. They are probably the newest regional DMU they own

Given the announcement is a lease extension, clearly ScotRail don’t own them!

 

[Russel]

Given the announcement is a lease extension, clearly ScotRail don’t own them!

I think we all know what was meant though.

 

[AlastairFraser]

Given the announcement is a lease extension, clearly ScotRail don’t own them!

Own lease potato pohtato in context

I think we all know what was meant though.

I'm glad to hear that you understood