ScotRail Suburban Fleet (EMU and BEMU) Market Engagement

[TrainViation]

Just 3 weeks to go until the date tender said would dispatch invitations to selected candidates, wonder when that shortlist will become public

https://www.publiccontractsscotland.gov.uk/search/show/search_view.aspx?ID=NOV542816

There gave themselves generous 6 months to reduce the participation list to a short list, so would hope there are no delays

Will the shortlist actually come out on the 17th in four days? Or is it likely just another missed target date?

 

[Highlander1]

Will the shortlist actually come out on the 17th in four days? Or is it likely just another missed target date?

Where does it say the shortlist will be released to the public?

 

[TrainViation]

Where does it say the shortlist will be released to the public?

It doesn't specifically say that it will be released, but I presume something must come of this decision publicly?

 

[Highlander1]

It doesn't specifically say that it will be released, but I presume something must come of this decision publicly?

Probably not. Nothing was during the HST replacement procurement.

 

[Snow1964]

It doesn't specifically say that it will be released, but I presume something must come of this decision publicly?

It's the 17th today, the date they said bidders on shortlist would be informed. But doesn't look like there has been a public announcement (yet)

Probably not. Nothing was during the HST replacement procurement.

HST replacement wasn't really open competition with lots of bidders, it was more a fudge to get 222s as only practical solution for interim period, until lines has sufficient electrification to have new regional BEMUs in 10-15 years

 

[waverley47]

It's the 17th today, the date they said bidders on shortlist would be informed. But doesn't look like there has been a public announcement (yet)

I can confirm that the relevant bidders have been informed.

I am not at liberty to disclose the list, but there is a draft public statement sitting there should the bidders and the government consent to it being made public.

 

[Highlander1]

It's the 17th today, the date they said bidders on shortlist would be informed. But doesn't look like there has been a public announcement (yet)

HST replacement wasn't really open competition with lots of bidders, it was more a fudge to get 222s as only practical solution for interim period, until lines has sufficient electrification to have new regional BEMUs in 10-15 years

It still has to go through the same process

 

[TrainViation]

I can confirm that the relevant bidders have been informed.

I am not at liberty to disclose the list, but there is a draft public statement sitting there should the bidders and the government consent to it being made public.

May I ask how many bidders have been informed? Or would that still classify as sensitive information until consented to.

 

[waverley47]

May I ask how many bidders have been informed? Or would that still classify as sensitive information until consented to.

I think I'm limited by what I can say on that one, unfortunately. I can say though, it's not an unexpected number

 

[Strathclyder]

I'm well aware of the complex process that's involved with tenders/bids like these and the desire to get it right - especially in light of how disastrous CMAL's Large Vessel replacement/renewal programme for CalMac has been and a repeat of that with ScotRail's fleet renewal/replacement is best avoided as far the Scottish Government is concerned, to say nothing of the 701 & 810 fisacos south of the border making the Juniper's problems at the turn of the century look trifling by contrast - but it does feel like it's taken a painfully long time to even reach this stage.

I'm fully expecting it to be another couple months at least before we hear anything else - October/November potentally. Not expecting anything as major as a order being placed before the last quarter of 2027/first quarter of 2028 at the earliest. Based on past experiences, I believe it's best to manage one's expections and hope the current stock continues to soldier on in the meantime without suffering a catastrophic, sustained drop in reliabilty/availabilty.

This is hardly a bad thing...

Personally, I can certainly understand the sentiment, given that Glasgow/Strathclyde is A) my 'local' part of the wider network and therefore that can always skewer one's perception of it being left behind or forgotten regardless of the reality behind the scenes or the broader picture, well away from us 'normies' (by which I mean me) and B) now the last stronghold of Mk3-based EMU operation in the UK with more than one line relying on them to provide all of or a good chunk of their services.

Yes, it's indisputable that the 318/320 fleet has been helped by regular overhauls, ScR keeping on top of maintenance as best they can and having a sizable - but finite - spares pool to draw from (certainly when compared to the younger and unique 323s) by dint of them being part of the wider Mk3-based EMU family, but that doesn't change the fact that the 318s are now the oldest EMUs in regular service anywhere on the network and the second-oldest MUs period after the 150s (40 years of service will be reached at the end of September, so less than 8 weeks away), with the 320s not far behind at 36-37 years.

 

[waverley47]

Unfortunately one of the reasons this one is taking so long is that a lot of the technology is proprietary, and very new.

This order will be the largest single order of BEMUs to date anywhere on the planet, as far as I'm aware.

There has been an order for the DART across the Irish Sea, with a whole multitude of problems already arising related to the battery element. Eighteen are on order from Alstom for New Zealand, obviously there are some of the 777s down in Merseyrail land, some two car Japanese units. But these 28 units will be the largest single order, with quite a lot of coaches up for grabs. Looking across at Dublin has made a lot of the team quite uncomfortable with what some of the builders were offering, and there's been a request for more data about what they can actually deliver.

The proprietary nature of the technology, of charging methods, of the actual batteries themselves, also makes it more difficult. If you're ordering an EMU, you can be pretty specific about what you want, and still find that a dozen companies can all offer a suitable product. We've been building for well over a hundred years after all. If you're specifying a battery, you might specify a particular charging rate, or a certain energy density, and find that actually only one or two companies could proveably meet the requirements.

I'm obviously limited in what I can post on here, but the actual process of getting it right, when the companies themselves are unsure as to what they could offer and then follow through on, is unbelievably complex.

 

[GraphitProjekt]

Yeah I feel Scotland is really acting like a huge pilot scheme for serious discontinuous operation. Core Valley Lines battery trains are off wires for about 5 miles max. So Fife Circle is like a different order of magnitude. Even orders of much less experimental fleets can simply take years to materialise and come across all sorts of hurdles along the way. If the electrification schemes are allowed to continue past the current Fife Circle plan, I wonder how much they can actually wire up before the battery trains are even at the live testing stage.

uncomfortable with what some of the builders were offering, and there's been a request for more data about what they can actually deliver....when the companies themselves are unsure as to what they could offer and then follow through on

Considering the other big order for Northern, and the suggestions of a Chiltern order, perhaps what we're looking at bears a passing resemblance to 1955.

 

[TrainViation]

If the electrification schemes are allowed to continue past the current Fife Circle plan, I wonder how much they can actually wire up before the battery trains are even at the live testing stage.

Current estimates of the entry into operation *were* late 2031, meaning probably late 2030 live testing at the earliest. And these estimates don’t account for possible delays.

From what I’ve personally gathered, Haymarket to Dalmeny is due to go live next March, the Fife Circle itself is due to be partially electrified by 2029 including Leven, Kirkcaldy, Cardenden and Ladybank. The Dundee scheme has a contract tender going for £450m which will include improvements from Dundee up to Montrose and is expected around 2027-2028 up to 2032/2035(?).

So most likely Fife will be partially wired, plus Dundee and Perth bay platforms and maybe a bit extra around the Arbroath area.

 

[Snow1964]

Unfortunately one of the reasons this one is taking so long is that a lot of the technology is proprietary, and very new.

This order will be the largest single order of BEMUs to date anywhere on the planet, as far as I'm aware.

I think Scotrail order will be largest by number of vehicles, but not trains.

North Rhine Westphalia network ordered 61 BEMUs from Siemens last year, and financing was confirmed by Rock Rail in April 2026

České dráhy (ČD) of Czechia tendered in January for 120 BEMUs (so lot more than Scotland), 40 of type 130 with 121 seats, and 80 of type 135 with 140 seats. Not ordered yet but have guaranteed a minimum of 13 type 130 and 7 type 135

Both Slovakia has ordered 16 BEMUs, and Latvia 16 (9 firm, 7 options), both from Škoda group. I don't know if Škoda are on the Scotland Shortlist

So although the technology is relatively new, they will not be pioneers with all the production risk, as a number of countries are ahead of Scotland.

 

[Ben Conlin]

Siemens look to be one of the, if not the most experienced with delivered BEMUs currently. In terms of what’s public in the UK for designs their Desiro Verve looks promising. Alstom released images of their new Adessia UK today as well but can understand the concerns with them because of the Irish battery problems.

 

[Strathclyder]

Siemens look to be one of the, if not the most experienced with delivered BEMUs currently. In terms of what’s public in the UK for designs their Desiro Verve looks promising. Alstom released images of their new Adessia UK today as well but can understand the concerns with them because of the Irish battery problems.

I'd throw Stadler into the mix here with the FLIRT platform as there is precedent. Far be it from me to speculate (though I do feel I have a vested interest, given this will be the biggest stock renewal for the North Clyde/Argyle Lines since the 334s arrival), but if they were the ones to get the order, an improved derivative of the 756 would be the best route to go down for the BEMUs with a shorter 745 variant acting as the 318/320 replacement.

Who's to say though? For all us normies know right now, Skoda could end up getting the order.

== Doublepost prevention - post automatically merged: 1 Aug 2026 ==

Unfortunately one of the reasons this one is taking so long is that a lot of the technology is proprietary, and very new.

This order will be the largest single order of BEMUs to date anywhere on the planet, as far as I'm aware.

There has been an order for the DART across the Irish Sea, with a whole multitude of problems already arising related to the battery element. Eighteen are on order from Alstom for New Zealand, obviously there are some of the 777s down in Merseyrail land, some two car Japanese units. But these 28 units will be the largest single order, with quite a lot of coaches up for grabs. Looking across at Dublin has made a lot of the team quite uncomfortable with what some of the builders were offering, and there's been a request for more data about what they can actually deliver.

The proprietary nature of the technology, of charging methods, of the actual batteries themselves, also makes it more difficult. If you're ordering an EMU, you can be pretty specific about what you want, and still find that a dozen companies can all offer a suitable product. We've been building for well over a hundred years after all. If you're specifying a battery, you might specify a particular charging rate, or a certain energy density, and find that actually only one or two companies could proveably meet the requirements.

I'm obviously limited in what I can post on here, but the actual process of getting it right, when the companies themselves are unsure as to what they could offer and then follow through on, is unbelievably complex.

A-yep.

All this certainly explains why in the recent lease extensions for the 318s & 320s to 2032, there's a one year option to extend them further still to 2033, which, when looking back on the past 3 introductions of new-build Scottish EMUs, which were all fraught with problems, heavily delayed in one way or another and forced existing rolling stock to stagger on far longer than first intended - 334s, 380s and 385s - is a prudent move.

No doubt included to give a easy method of cover in case things go completely tits-up in the testing/commissioning process of these things without having to fish around for non-existant used units as short-term cover; the 365s aren't around to dig ScotRail out of that kind of hole again.

 

[positron]

The Welsh valleys is longer than 5 miles off wires given that the 756s will run from Queen Street all the way to Bridgend and back, they admittedly have a diesel engine but I believe they intend to largely run off the battery's with the diesel mostly a just in case (especially for when the battery's start degrading).

The 398 + 756 order must be fairly high up in terms of battery train order size too.

But ScotRail are absolutely taking a big leap with this procurement. I can see it being successful given they're actually doing the wiring sections to make it work. I don't see how GWR hope to make use of BEMUs with essentially no wires on basically any of their network.

 

[GraphitProjekt]

The Welsh valleys is longer than 5 miles off wires given that the 756s will run from Queen Street all the way to Bridgend and back, they admittedly have a diesel engine but I believe they intend to largely run off the battery's with the diesel mostly a just in case (especially for when the battery's start degrading).

Yeah essentially there's no worry for running out of charge in any scenario as the engine has effectively infinite range for any problem that could arise. But in terms of there electric only fleet, the largest off wire-section I think is Caerphilly to Lisvane which is just under 3 miles. It's probably a fairly equal amount of mileage off wires when they're operating in the central area but that's a lot more complicated to figure out. So Scotrail is taking a big risk to actually implement a whole new operating model.

 

[anthony263]

The Welsh valleys is longer than 5 miles off wires given that the 756s will run from Queen Street all the way to Bridgend and back, they admittedly have a diesel engine but I believe they intend to largely run off the battery's with the diesel mostly a just in case (especially for when the battery's start degrading).

The 398 + 756 order must be fairly high up in terms of battery train order size too.

But ScotRail are absolutely taking a big leap with this procurement. I can see it being successful given they're actually doing the wiring sections to make it work. I don't see how GWR hope to make use of BEMUs with essentially no wires on basically any of their network.

Im sure i read somewhere that tfw said that a 756 can run Cardiff to Bridgend and back on batterie power without the generator kicking in.

 

[Snow1964]

Im sure i read somewhere that tfw said that a 756 can run Cardiff to Bridgend and back on batterie power without the generator kicking in.

Cardiff - Bridgend - Cardiff is about 47 miles

Not sure what battery capacity is planned for Scotland (and presumably a manufacturer will offer based on standard module sizes).

A 756 3car is 447 kWh and a 4car is 559 kWh
Apparently good for approx 50 miles (but presumably temperature, gradients and stopping patterns will vary that) which fits the 47 miles above.

Scotland can get very cold in the winter, which diminishes range, so guessing would need around 180+ KWh per vehicle to have 50 mile battery range. More realistically 200+ KWh per vehicle for bit of cold weather / snow delay contingency margin for a 50 mile electrification gap

 

[positron]

Cardiff - Bridgend - Cardiff is about 47 miles

Not sure what battery capacity is planned for Scotland (and presumably a manufacturer will offer based on standard module sizes).

A 756 3car is 447 kWh and a 4car is 559 kWh
Apparently good for approx 50 miles (but presumably temperature, gradients and stopping patterns will vary that) which fits the 47 miles above.

Scotland can get very cold in the winter, which diminishes range, so guessing would need around 180+ KWh per vehicle to have 50 mile battery range. More realistically 200+ KWh per vehicle for bit of cold weather / snow delay contingency margin for a 50 mile electrification gap

Admittedly the 756s do use space in the cupboard with the diesel engine. If Scotland procured a straight BEMU variant (they don't seem to be interested in diesel) they'd presumably get an extra battery pack in that space and so extra range.

 

[Davester50]

Admittedly the 756s do use space in the cupboard with the diesel engine. If Scotland procured a straight BEMU variant (they don't seem to be interested in diesel) they'd presumably get an extra battery pack in that space and so extra range.

Are they limited to only one power unit/module/car/ per unit, or can they have more than one?
50 Miles would be ample for Cupar to Dundee and return. Perhaps even Dundee to Arbroath and back too, but a reach for Dundee to Dunblane and return.

 

[positron]

I don't think there's any FLIRTs anywhere with multiple but I don't know if that means it's not possible, though like I say the 756 has a diesel engine and fuel tank to lug round, swapping that for a 4th battery pack would presumably increase the range a bit.

I also don't know how accurate the 50 miles figure is it might be that actual range is more, or that the engine gearing affects the range (I think they've prioritised acceleration over speed and that might impact battery draw).

 

[Class83]

I don't think there's any FLIRTs anywhere with multiple but I don't know if that means it's not possible, though like I say the 756 has a diesel engine and fuel tank to lug round, swapping that for a 4th battery pack would presumably increase the range a bit.

I also don't know how accurate the 50 miles figure is it might be that actual range is more, or that the engine gearing affects the range (I think they've prioritised acceleration over speed and that might impact battery draw).

Presumably gradient needs considering as well, Rosyth to Cowdenbeath (a section which would be run on battery) is an average gradient of 1/87 for 8 miles with 3 intermediate stops which is going to contribute to power consumption.

Battery draw will be a function of energy usage, accelerating a mass uses energy (E=1/2mv^2), pushing air out of the way to keep a mass moving at high speed uses energy (bit more complicated but roughly the square of the speed, so doubling speed quadruples drag), going up hills is lifting a mass (E=mgh) so more batteries might not help as they increase mass.

 

[stevieinselby]

Presumably gradient needs considering as well, Rosyth to Cowdenbeath (a section which would be run on battery) is an average gradient of 1/87 for 8 miles with 3 intermediate stops which is going to contribute to power consumption.

With regenerative braking, hills and stops have less of an impact on power consumption of battery trains than they do on diesel or electric trains.

 

[Peter Mugridge]

Presumably gradient needs considering as well, Rosyth to Cowdenbeath (a section which would be run on battery) is an average gradient of 1/87 for 8 miles with 3 intermediate stops which is going to contribute to power consumption.

Would that not be at least partly cancelled out by not needing to use so much power in the other direction?

 

[Nicholas Lewis]

Would that not be at least partly cancelled out by not needing to use so much power in the other direction?

You'll get back c60-70% of the energy expended in accelerating from regenerative braking and if it was non stop run down the gradient you could then harvest energy whilst holding the train at a certain speed to maximise recovery. That might come at the expense of extended sectional running times though and probably needs a degree of automation.

Be interesting to know what modelling ScotRail/NR did here to come up with the optimal balance between how much to wire versus how much energy the trains batteries need to contain. Really you would have wanted the rolling stock supplier to be part of that conversation and presumably as part of tendering some interaction has happened but will the overall system be optimised.

 

[Snow1964]

You'll get back c60-70% of the energy expended in accelerating from regenerative braking and if it was non stop run down the gradient you could then harvest energy whilst holding the train at a certain speed to maximise recovery. That might come at the expense of extended sectional running times though and probably needs a degree of automation.

Be interesting to know what modelling ScotRail/NR did here to come up with the optimal balance between how much to wire versus how much energy the trains batteries need to contain. Really you would have wanted the rolling stock supplier to be part of that conversation and presumably as part of tendering some interaction has happened but will the overall system be optimised.

Regeneration is probably limited, or capped, when batteries are above about 85% charged, because almost fully charged batteries have much lower charging rate.

It is also worth remembering that below about 10mph, friction brakes do the braking, regeneration is blended out as speed drops towards zero.

But if holding speed downhill (not at crawling speed) and battery is below about 80%, then can sometimes get nearer 85-90% of energy recovered, as that is optimum regen conditions

 

[Class83]

Would that not be at least partly cancelled out by not needing to use so much power in the other direction?

You'll get back c60-70% of the energy expended in accelerating from regenerative braking and if it was non stop run down the gradient you could then harvest energy whilst holding the train at a certain speed to maximise recovery. That might come at the expense of extended sectional running times though and probably needs a degree of automation.

Be interesting to know what modelling ScotRail/NR did here to come up with the optimal balance between how much to wire versus how much energy the trains batteries need to contain. Really you would have wanted the rolling stock supplier to be part of that conversation and presumably as part of tendering some interaction has happened but will the overall system be optimised.

The way the planned Scotrail works the trains will operate routes with partial electrification, so for the section described electrification ends at Dalmeny, trains will cross the Forth Bridge to Inverkeithing (which is fairly flat), then go up the hill described to Cowdenbeath before a slight descent to Lochgelly where the electrification resumes on their way to (mostly) Perth or Leven, in that section there is much less benefit from going downhill, there will be a little bit of regenerative braking at stations, but accelerating uphill will use more energy that is recovered for the full battery powered section. The reverse working will be fully charged when reaching the end of the electrification at Lochgelly, then only have a short climb before the descent so will be absolutely fine and probably not able to get much from regen, unless they deliberately don't fully charge under the wires which might actually be worth doing. But it doesn't average out in terms of battery capacity.

Presumably the route profiles, elevation, stopping pattern etc would form part of the tender and it's not x miles on level track and we hope it can make it up a hill with stops. Shawfair to Stow (southbound being uphill) on the Borders line may actually be the most challenging sector. Fife coast is relatively flat, as is Ladybank to Dundee, there is a some elevation on Ladybank-Perth.

 

[hwl]

[As someone who has done lots of rail battery and wider regen performance modelling professionally in multiple countries, but I haven't been involved with Scotrail BEMU work]

It is probably worth pointing out the regen energy wherever it goes (either to OHLE (or 3rd rail) or battery) is usually substantially less than most people estimate at first with real (safe) driving styles and routes hence more route distance than initial low ball estimates needs to be electrified.
To capture the maximum regen energy available in practice you need both larger traction motors and more powered axles the decent performance and upgraded braking resistors to match when battery or OHLE can't absorb the power so there is seamless braking performance for the driver.
E.g. the BEMU starting point would be the highest spec ends of the Aventra (345) or Desiro City (700) traction electrical system performance, ideally better. Lots of compromises on unit cost/weight vs maximising regen.

Most forum reader aren't probably aware but the max adhesion value assumptions for rheostatic /regen braking code in the software are ~ 0.16 substantially lower than for traction power on MUs (e.g 0.20 - 0.24 for <100mph units, 0.185 for 125mph units) hence the flat top on the Braking Effort curve is substantially lower than the Tractive Effort curve, as soon as you slow into the flat top area of the BE curve your energy recovery drops linearly with speed until friction braking kicks in. Depending on the OEM/ unit this reduction in regen energy starts above 30mph substantially reducing the overall recovery per deceleration cycle on regional routes with decent station stop density.

<insert any appropriate letters here>MU hotel and auxiliary loads are substantially higher than lay people estimate (if they estimate at all!). For Scotrail's EMU/BEMU spec the aux/hotel usage will be 150-180kW per unit. When taken into account this means that you really really want to minimise the time on battery and maximise the time on OHLE - hence any slowing down if overall timings permit will be done on electrified sections and not on battery sections (minimising total battery energy use) .
If the GWR 230 range trial PR day had actually involved sensible Hotel and aux loads e.g. having the lights and HVAC on then very optimisation different decision would have been made on optimal cruising speed (e.g. higher speed with with higher resistances) due to the greater steady state aux and hotel losses.
It is best to envisage the battery/aux. loads issues as bucket of water with a small hole in, you go as fast as possible between large hose pipes and spend as much time with a large hose filling the bucket as possible.

Siemens had a fairly educational advertorial in MR late last year pointing out that BEMUs would need a minimum of 25-30% of the route electrified. If it wasn't the right 25-30% then you would need even more electrification overall. [I agreed with both their comments]. But Siemens could help you get the right 25-30% with their SFC and supply battery tech if the problems was lack of power in the right place(s) which it isn't on Borders or Fife as there are simple enough options on supply (even if only one sensible option, there was an option without innovate power supplies).

As some other comments have noted, only a small number of OEMs are capable of delivering a product to meet Scotrail specifications in practice, and only some of them at vaguely sensible price point. Realistically the short list would be quite short but those not on it kicking up fuss hence lots of extra entertainment (and cost) for Scotail and their advisers though having a longer short list.