Should someone be taking a grip on new train procurement?

[Zomboid]

I don't see what the issue would be with a flirt style battery module. Most of the routes where trains are length limited are already electrified so wouldn't need batteries anyhow.

 

[Brubulus]

I don't see what the issue would be with a flirt style battery module. Most of the routes where trains are length limited are already electrified so wouldn't need batteries anyhow.

Mainly that it's unnecessary. Though there isn't really an issue with it. Assuming we have 4 cubic metres to work with, and the train will be equipped with BYD Blade batteries, with an energy density of around 448wh per litre, this gives just under 1.8MW per coach, even with reductions to accommodate for cooling systems etc, gives around 1.5MW.

A relatively aerodynamic (and long) train at 125mph uses around 2.5KW per vehicle mile (educated guess, if anyone has better figures use those instead). Assuming that the unit in question is a 10 car train, this will give an actual range of 60 miles, and a service range of around 40 miles at top speed. 2 batteries will increase the available range to around 80 miles at 125, even though the vast majority of un electrified routes are nowhere near 125mph.

If the railway was to take decisive action now and put fast chargers at key termini which are far from electrification, such as Penzance, Exeter, Aberdeen and Inverness, it's likely that the 80x could have their GUs replaced with batteries very soon, revolutionising performance. The 810s could have their engines removed before they even go into service, being around 70miles each way from Wigston to Sheffield.

 

[Snow1964]

I will reiterate that, unless a Class 756 style solution is utilised, the GB loading gauge cannot accommodate underfloor traction batteries on a fully motorised, low-floor vehicle.

Is this some form of weight restriction you are thinking about, or are you referring to units with both battery and diesel. There is very little need for units with diesel engines for next 15 or 20 years (as there are are many DMUs under 20-25 years old, working services that could be BEMU, so cascading the diesels to areas with no part electrification is possible in interim)

Modern ac motors fit within bogie frame, and modern power electronics for the control system not much bigger than couple of shoeboxes.

Even fitting things like compressors, air reservoir tanks, toilet retention tank under the floor is not going to take up all the space. There won't be a diesel alternator or fuel tanks taking up space on a BEMU

Battery modules can be fairly slim vertically, don't need the height that a diesel unit takes, so should easily fit under a floor that is 200-300mm lower.

I accept that through gangways between units need to be at current height to clear couplers, so would need sloping floor up to unit ends, but the intermediate gangways can be set lower and floor at height between low floor section and current high floor (it's not like we split units normally).

I have been on units in Italy where the seats near the wheels are over a raised floor with sunken gangway (similar to you get at rear of many buses), so don't even need to fit small wheel bogies. This arrangement is proven in Europe, so don't need to reinvent the wheel and create something that is untested and new.

 

[HSTEd]

If we take a BYD blade cell data sheet as an example, the pack is going to be more or less three blades wide (3x945mm = 2.84m or so).
If we assume the pack is 15m long, it will be able to stack 1080 rows of cells, for 3240 in total.

Each cell weighs 2.54kg, stores 454Wh (at C/10) and has rated outputs of 790W continuous and 1530W peak.

The Battery cells weigh ~8300kg, hold 1.47MWh and can output 2.6MW continuous and 4.9MW peak.

As a random example, a TGV Duplex trainset uses about 18kWh/train-km at cruise. This one pack could move that entire train 81km.
It is clear that such a battery pack, if positioned under each vehicle in a train, could propel the train very long distances.
Long enough distances to make diesel generators unnecessary.

The peak battery output rating of a four car train would approach the power requirement of a 400m Shinkansen trainset.

EDIT:
Peak rating is for 5 minutes, apparently, but a traction limited train will reach very high speeds very quickly. 125mph would be reached in something like 45 seconds at 1.3m/s^2.

 

[Zomboid]

There does need to be space for things that aren't batteries under the carriages. What's the volume of the engine rafts and fuel tanks?

I suspect the BYD cell isn't designed to be charged and discharged several times a day, which would be the likely use case on a train. It'll have a pretty short lifespan compared to use in a car, and it probably won't be able to be used at car density without thermal issues manifesting.

Though I appreciate that the example is extreme and you wouldn't necessarily need that kind of density anyhow.

 

[Trainbike46]

There does need to be space for things that aren't batteries under the carriages. What's the volume of the engine rafts and fuel tanks?

We really shouldn't be building any new trains with diesel engines anymore. The next generation of trains should really be EMUs and BEMUs, with existing diesel cascaded to routes that aren't yet suitable to (B)EMU operation.

I suspect the BYD cell isn't designed to be charged and discharged several times a day, which would be the likely use case on a train. It'll have a pretty short lifespan compared to use in a car, and it probably won't be able to be used at car density without thermal issues manifesting.

Though I appreciate that the example is extreme and you wouldn't necessarily need that kind of density anyhow.

The point is mostly that batteries are much more flexible in size than diesel engines are, and making thin packs that would easily fit under a low-floor train is really easy.

 

[Zomboid]

We really shouldn't be building any new trains with diesel engines anymore. The next generation of trains should really be EMUs and BEMUs, with existing diesel cascaded to routes that aren't yet suitable to (B)EMU operation

I agree, but the point was that the space actually l available isn't the whole underfame if we're taking that approach. It's the space that's currently occupied by the diesel engines.

 

[HSTEd]

There does need to be space for things that aren't batteries under the carriages. What's the volume of the engine rafts and fuel tanks?

I honestly don't think you need engine rafts and fuel tanks.
Battery ranges are now sufficiently long that even minimal investment in suitable chargers or electrification would eliminate the need for diesel operations entirely.

Let's say a 320kph Duplex is comparable to a British 8x23m train, for the sake of argument.
It'd be over 500km of battery range!

Almost all UK railway operations would probably be tenable with that much charge, with opportunities for en route charging from electrification.

EDIT:

I see what you mean, but the volume of these engines is still significant.
A QSK-19 has a volume of around 2.8 cubic metres without a generator.

I suspect the BYD cell isn't designed to be charged and discharged several times a day, which would be the likely use case on a train. It'll have a pretty short lifespan compared to use in a car, and it probably won't be able to be used at car density without thermal issues manifesting. Though I appreciate that the example is extreme and you wouldn't necessarily need that kind of density anyhow.

I expect in this operational environment the capacity factor will tend towards a car battery pack given you would be accelerating only for tens of seconds at a time.
But yes, a real pack is probably going to have somewhat lower density, but the potential is celarly enormous.

 

[Brubulus]

There does need to be space for things that aren't batteries under the carriages. What's the volume of the engine rafts and fuel tanks?

I suspect the BYD cell isn't designed to be charged and discharged several times a day, which would be the likely use case on a train. It'll have a pretty short lifespan compared to use in a car, and it probably won't be able to be used at car density without thermal issues manifesting.

Though I appreciate that the example is extreme and you wouldn't necessarily need that kind of density anyhow.

The situation which @HSTEd described is pretty conservative given that there is only a single layer of battery (about 10cm). Even a low floor train would be able to contain and thermally manage at least 2 layers of battery. Secondly batteries can be effectively recycled to less demanding duties over time, so I'd guess actual lifespan of the batteries will be around 10-15 years of railway use, which is completely fine, given the relatively low cost of modern batteries.

An HST needs around the equivalent of 20kw per train mile at 125mph, so the range estimate is also highly conservative given the UK network.

 

[stuu]

An HST needs around the equivalent of 20kw per train mile at 125mph, so the range estimate is also highly conservative given the UK network.

What about hotel power?

 

[HSTEd]

What about hotel power?

In trains that move as fast as most UK ones do, the hotel load will be much smaller than the traction load.

In an hour a HST on the ECML could travel 80 miles, using ~1600kWh. For an average power of 1600kW.

The hotel load will probably be a couple of percent of that.

 

[Technologist]

I guess I am more extreme than most - I forsee a need for only two classes of train.

A pointy end fast train, probably battery assisted electric. Good to speeds of 320kph.
A gangwayed flat end train, battery assisted electric. Speed up to 170kph.

Both classes should be able to work in multiple (obviously the pointy end one can't use the gangway but you know).
Both classes should use the same charging adapter for static charging.
Both classes should be dual or tri voltage (25kV and 750V for sure, if 1500V is cheap, add it too)
Both classes should have all axles motored.
Both classes should have TGV M/Avelia Horizon style rapid refit interiors.

Both classes should offer at least partial level boarding from UK platforms. The slower class should probably be level boarding throughout.

If those desigsn can be developed then a combined order or 500 vehicles per year forever would set the railway up very well, even allowing for modest traffic growth.

I think we'll always be able to improve things, particularly if we get the infrastructure and the rail vehicles enabling each other. Secondly to look more broadly rail will be competing in a space with automation on the roads. Shared automation will enable more road capacity (add extra 0.14 passenger to every car and you have just added rails total capacity to the system). The longer term planning horizon rail will have to deal with electric regional air.

My view is that anything which can't be run as a metro (either conventional metro or high speed intercity metro like an improved Shinkansen) is going to end up closed. Rail will be forced to do the following to avoid closures,

1: Leverage autonomous car technology, it's a more complex task and its being achieved with set ups that cost £1000-20,000 per vehicle. The idea of spending £1 million for a vehicle to be made ready for but not equipped with ETCS is just crazy. It strikes me that the whole ETCS programme is actually making this whole process excessively slow and that GBR could probably get a bunch of tech start-ups in and get the whole UK system up to ETCS 3/4 equivalent in just a few years. To be remotely competitive in the future rail's base infrastructure costs need to come down, one way to do that is to dispense with the incredible quantity of cables we have running down the side of lines, smart trains and devices (possibly more locally powered) dum tracks.
2: Given that we are going to get ETCS on all lines there is then the question of speeding everything up. Again going back to automotive, why isn't every new train running active suspension (again we can get this on relatively ordinary cars), why isn't the default UK train tilting? Any line which isn't faster than the equivalent car journey isn't going to survive so we will need to speed things up once everyone has access to a taxis for less than the cost per mile to operate your own car.
3: I am actually quite interested stuff like Magrail which uses some variation on Inductrack to create a Maglev system which is backward compatible with conventional rail. With a bit of tilting HS2 could do 500kph.

== Doublepost prevention - post automatically merged: 27 Jun 2025 ==

In trains that move as fast as most UK ones do, the hotel load will be much smaller than the traction load.

In an hour a HST on the ECML could travel 80 miles, using ~1600kWh. For an average power of 1600kW.

The hotel load will probably be a couple of percent of that.

I have used the IET specs to spec my battery train, a 5 car IET had to use under 4600KWh going between London and Newcastle, works out as 18kwh/mile.

https://assets.publishing.service.gov.uk/media/5a79b82e40f0b63d72fc7f58/tts-redacted.pdf

Fitting batteries in is trivial on a space basis, using the class 801 as an example the fuel tanks and engine occupy several cubic meters on their own. You are going to run out of mass long before you run out of room. My 10% battery IET based example has 3700KWh of battery, but it has 5 coaches so that's 740KWh per coach. Or 7 Tesla battery packs per carriage.

 

[HSTEd]

My view is that anything which can't be run as a metro (either conventional metro or high speed intercity metro like an improved Shinkansen) is going to end up closed. Rail will be forced to do the following to avoid closures,

Ultimately, with the sorts of acceleration performance that a battery assisted unit will be capable of, anything 100mph is probably going to be at least somewhat competitive to cars.
125mph will crush it!

1: Leverage autonomous car technology, it's a more complex task and its being achieved with set ups that cost £1000-20,000 per vehicle. The idea of spending £1 million for a vehicle to be made ready for but not equipped with ETCS is just crazy. It strikes me that the whole ETCS programme is actually making this whole process excessively slow and that GBR could probably get a bunch of tech start-ups in and get the whole UK system up to ETCS 3/4 equivalent in just a few years. To be remotely competitive in the future rail's base infrastructure costs need to come down, one way to do that is to dispense with the incredible quantity of cables we have running down the side of lines, smart trains and devices (possibly more locally powered) dum tracks.

The problem with the ETCS rollout is not really the tech itself.
Its a dysfunctional and atrophied signalling industry that is struggling to physically deliver assets.

If you have money, I'd suggest it would be on fixing the physical deployment issues rathe than anything else.

2: Given that we are going to get ETCS on all lines there is then the question of speeding everything up. Again going back to automotive, why isn't every new train running active suspension (again we can get this on relatively ordinary cars), why isn't the default UK train tilting? Any line which isn't faster than the equivalent car journey isn't going to survive so we will need to speed things up once everyone has access to a taxis for less than the cost per mile to operate your own car.

Active suspension on trains only gets a little tilt, I think its about 1 degree on the latest N700.
I'm not sure it would do much in the UK context.

As for conventional tilting technology, it has a lot of weight disadvantages.
But as noted, the acceleration that is available with modern electronics, batteries and motors would provide major journey time improvements as is.

Especially allowing timetable simplification.

As an example:
The 100mph speed limit northbound at Grantham actually becomes limiting for a train accelerating away from a stand. Best guess the train will reach 100mph just as the nose of the train passes the 115mph sign, but I believe the sign only applies once the train has actually cleared it.
You'd probably have to do a drop in conversion to ETCS Level 1 LS to get more flexible speed limit supervision to satisfy the regulator you won't get huge numbers of overspeed accidents!

 

[35B]

Ultimately, with the sorts of acceleration performance that a battery assisted unit will be capable of, anything 100mph is probably going to be at least somewhat competitive to cars.
125mph will crush it!



The problem with the ETCS rollout is not really the tech itself.
Its a dysfunctional and atrophied signalling industry that is struggling to physically deliver assets.

If you have money, I'd suggest it would be on fixing the physical deployment issues rathe than anything else.

Active suspension on trains only gets a little tilt, I think its about 1 degree on the latest N700.
I'm not sure it would do much in the UK context.

As for conventional tilting technology, it has a lot of weight disadvantages.
But as noted, the acceleration that is available with modern electronics, batteries and motors would provide major journey time improvements as is.

Especially allowing timetable simplification.

As an example:
The 100mph speed limit northbound at Grantham actually becomes limiting for a train accelerating away from a stand. Best guess the train will reach 100mph just as the nose of the train passes the 115mph sign, but I believe the sign only applies once the train has actually cleared it.
You'd probably have to do a drop in conversion to ETCS Level 1 LS to get more flexible speed limit supervision to satisfy the regulator you won't get huge numbers of overspeed accidents!

And the impact on those not strapped in of such dramatic acceleration?

 

[HSTEd]

And the impact on those not strapped in of such dramatic acceleration?

That sort of acceleration is only tube train level, and people aren't strapped in for that!

The train would accelerate like a tube train and then keep going up to very high speed.