Driving technique: Does it really impact fuel usage?

[PudseyBearHST]

Mod Note: Posts #1 - #2 originally in this thread.

Whatever the going rate is for red diesel is at the point they buy it. Which has been very volatile recently due to Mr Trump. Its coming down to more sensible levels again.

Enough for the Iran war to affect services and recruitment

https://www.telegraph.co.uk/news/2026/05/27/transpennine-express-asks-labour-bailout-fuel-bills/

Although, trains get filled at depots regardless of cost, with tanks taking between 1200-2000 litres if empty.

Thanks for the replies.

Does eco-driving really affect mpg? E.g. drivers who coast 125 -> 100 instead of accelerating the whole and braking. Eco-driving is heavily emphasised, does it really make a difference out of interest?

Let’s say on a 4 power notch controller, you accelerated using notch 4 to linespeed or notch 3 to linespeed, which is more efficient? Of course, notch 4 uses more power but you get to linespeed in less time so how does it compare?

Thanks

 

[Unobrow]

Thanks for the replies.

Does eco-driving really affect mpg? E.g. drivers who coast 125 -> 100 instead of accelerating the whole and braking. Eco-driving is heavily emphasised, does it really make a difference out of interest?

Let’s say on a 4 power notch controller, you accelerated using notch 4 to linespeed or notch 3 to linespeed, which is more efficient? Of course, notch 4 uses more power but you get to linespeed in less time so how does it compare?

Thanks

It’s an interesting argument.

I think it was Salford City Transport back in the 50’s decided to order their Leyland buses with the larger 9.6 litre engine over the smaller 7.4 litre unit.

Their thoughts were (I assume based on proven running with both), was that a larger engine being used lightly (not laboured), uses less fuel than a smaller engine working harder. It seemed to be the case too.

I’ve used your notch 3/4 reasoning in my professional road driving days and agree that accelerating harder gets to speed quicker where the engine then cruises.

However, in the case of a class 66 for example, it’s not quite as cut and dry. Notch 8 produces around 3000hp at the rail I think it is, where 7 produces 2300. But N8 uses 25% more fuel as the supercharger and turbo are both in.

You do get up to speed quicker, but I enables aren’t always that tightly timed and other late running trains could cause delays to you, so there’s more variables at play to make it a simple answer.

 

[XFeed]

I can`t remember if it was ATW or TfW that fitted the DAS - Driver Advisory System - to 175s in an attempt to save fuel by advising the driver to coast at certain points as it calculated the time to the next station and by coasting it would reach the station on time thus saving fuel.

It wasn't always operational as getting replacement parts out of ATW or TfW was so difficult.

@craigybagel may be able to share more light on its effectiveness as I`m sure he would have had some experience of it ?

 

[DarloRich]

My heavy foot in the car or van certainly does so surely driving style will have an impact on train fuel usage!

 

[rmHawk765]

I can`t remember if it was ATW or TfW that fitted the DAS - Driver Advisory System - to 175s in an attempt to save fuel by advising the driver to coast at certain points as it calculated the time to the next station and by coasting it would reach the station on time thus saving fuel.

I've definitely seen this on a Hull Trains 802, I think GWR and LNER have it fitted too, but I do seem to hear it's not particularly reliable.

 

[XFeed]

I've definitely seen this on a Hull Trains 802, I think GWR and LNER have it fitted too, but I do seem to hear it's not particularly reliable.

I seem to recall that reliability wasn`t great at times, hence trying to get parts from the TOC.

 

[craigybagel]

I can`t remember if it was ATW or TfW that fitted the DAS - Driver Advisory System - to 175s in an attempt to save fuel by advising the driver to coast at certain points as it calculated the time to the next station and by coasting it would reach the station on time thus saving fuel.

It wasn't always operational as getting replacement parts out of ATW or TfW was so difficult.

@craigybagel may be able to share more light on its effectiveness as I`m sure he would have had some experience of it ?

It was ATW who put DAS in, not just on 175s but on 150s, 158s and the MKIII DVT's as well. I don't know anything official about how successful it was, but people may be able to draw their own conclusions given how the user licence was allowed to lapse. It's also built into the cabs of the 197s but has so far never been operational.

I wasn't keen on following it's instructions; saving a bit of fuel to arrive on time rather than early is all well and good, but if you then end up leaving late because of an unforeseen delay (like assisting a passenger with a ramp at an unmanned station) it's probably a false economy.

The best thing most drivers could say about it, and what is truly missed now, was it gave you your exact mileage down to the quarter mile. In a world where mileposts are rarely kept clear of foliage, that was very handy.

 

[NY SAARSS]

how much fuel does a train use carrying fuel around in a tank that wont bee needed. a post earlier in the thread said tanks are filled at the depot between 1200 and 2000 litres. if the train is doing 100 miles end to end and uses i dont know say 250 litres how much does it use to carry the extra fuel in the tank. if 100 miles was 250 litres and the tocs wanted better economical journeys would they be better putting less in a tank. Dont know how heavy a litre of fuel is but carrying enough for one journey and a small bit for diverts/delays would save fuel. Always thought thats how most airlines operated

 

[boiledbeans2]

[...]
I think it was Salford City Transport back in the 50’s decided to order their buses with the larger 9.6 litre engine over the smaller 7.4 litre unit.

Their thoughts were (I assume based on proven running with both), was that a larger engine being used lightly (not laboured), uses less fuel than a smaller engine working harder. It seemed to be the case too.
[...]

I'm not sure about engines from back then, but modern engines usually have the best efficiency in the higher torques.
Hence, the Pulse and Glide eco-driving technique, which you can read about here:

Energy-efficient driving - Wikipedia

en.wikipedia.org

A quote from the above link:

During the pulse (acceleration) phase of pulse and glide, the efficiency is near maximal due to the high torque and much of this energy is stored as kinetic energy of the moving vehicle. This efficiently obtained kinetic energy is then used in the glide phase to overcome rolling resistance and aerodynamic drag.

 

[dk1]

We have C-DAS but that doesn’t mean we have to pay any attention to it. The only time fuel usage was ever mentioned was during the fuel depot blockades in the year 2000. We were asked to avoid using notches 6 & 7 on 15X units. Apart from that it’s always been drive how you like.

 

[172007]

DAS was installed on LM class 172's as part of a franchise commitment. Only thing that was usefull was providing the trains milleage on the route which was usefull for temporary speed restricton commencement points and reporting exact locations etc.

The system was a dismall failure as to keep to the timetable full power is generally required and class 172's don't coast but lose speed. It would confuse which line you was on and give wrong speed limits too. It would hive and eco score but no one could ever get a good score and it hardly varied with driving style either. It has been switched off for over 6 years now.

 

[dk1]

DAS was installed on LM class 172's as part of a franchise commitment. Only thing that was usefull was providing the trains milleage on the route which was usefull for temporary speed restricton commencement points and reporting exact locations etc.

Yes the mileage is useful. When initially being installed onto the TMS screens on our 745/755 fleet the training school said that at long last you’ll all have an in-cab clock now as we know most of you will ignore any advice it gives you

 

[800301]

I've definitely seen this on a Hull Trains 802, I think GWR and LNER have it fitted too, but I do seem to hear it's not particularly reliable.

We have some form of DAS fitted to the 80x’s and 387 but not in a 16x.

Currently in an 80x it doesn’t work, in a 387 it works for most headcodes and at the end of a trip tells you how much energy you’ve used or saved based on its “Advice” normally advising you to coast or reduce your speed to the bare minimum to meet the timetable, it doesn’t however say that we can’t take full power etc so not entirely sure how it works out energy used, if you don’t follow the advice it displays a message something like “Speed profile not being followed”

I don’t see much of the point on an electric train as electric is a fixed cost as far as I’m aware, where as if you’re saving in fuel, there is actually money to be saved, so not sure why it’s not in our DMU fleet, although I’m sure savings could be made if engines were shut down as much as possible

 

[saismee]

I don’t see much of the point on an electric train as electric is a fixed cost as far as I’m aware, where as if you’re saving in fuel, there is actually money to be saved, so not sure why it’s not in our DMU fleet, although I’m sure savings could be made if engines were shut down as much as possible

The cost benefit should be similar on electric trains, though they can have the benefit of regenerative braking. 755s have their engines shut down as much as possible (if the driver remembers and is in an electrified platform), idling on electric while not in service.

 

[dk1]

The cost benefit should be similar on electric trains, though they can have the benefit of regenerative braking. 755s have their engines shut down as much as possible (if the driver remembers and is in an electrified platform), idling on electric while not in service.

Yes if 15mins or more in an electrified platform we are instructed to pan up. Leaving it in diesel with no key on causes it to shut itself down and eventually lock itself up trapping anyone onboard. In electric and keyed off all air-con and other functions stay fully working and it’s a quick start for the next driver taking over.

 

[saismee]

Yes if 15mins or more in an electrified platform we are instructed to pan up. Leaving it in diesel with no key on causes it to shut itself down and eventually lock itself up trapping anyone onboard. In electric and keyed off all air-con and other functions stay fully working and it’s a quick start for the next driver taking over.

Nearly happened to me recently. The train does tell passengers to leave at the nearest available door but the train was due to depart in 3 minutes. It was the last one of the night so I was not going anywhere! It never locked up as the driver restarted the engines in time. I believe it goes into power saver mode after 30 minutes.

 

[dk1]

Nearly happened to me recently. The train does tell passengers to leave at the nearest available door but the train was due to depart in 3 minutes. It was the last one of the night so I was not going anywhere! It never locked up as the driver restarted the engines in time. I believe it goes into power saver mode after 30 minutes.

Yes it’s around 30 minutes when the doors lock. After 15-20 it starts telling everybody to leave. Doesn’t affect Ipswich, Cambridge or Colchester unless the pan(s) are isolated but happens quite a bit in platform 6 at Norwich.

 

[CapabilityB]

It's part of the business case for ETCS that trains will operate more efficiently

 

[bahnause]

Energy-efficient driving has always been an important part of training. Letting the train coast, making the most of gradients and consistently utilising dynamic braking to the full have therefore been standard practice for years.

In addition, two further systems have been introduced in recent years. Firstly, optimised running speeds combined with a punctuality display, which is updated at every signal, and secondly, conflict management, which issues short-term speed recommendations to prevent unwanted stops and the train having to accelerate again.

These two systems save approximately 120 GWh per year across the SBB network. This applies to electric traction. For diesel trains, with their lower and more variable efficiency, the savings are likely to be significantly higher still.

 

[martin2345uk]

We (Eurostar) have a DAS system on the newer trains, it's pretty good when it actually works, tells us a target speed to maintain and when to coast (it knows all the gradients etc). Apparently saves a ton of energy

 

[Nym]

It's part of the business case for ETCS that trains will operate more efficiently

Except it won’t because it’s also to “enable more efficient timetables” by making trains drive harder.

Also one needs to account for the fact that humans are not good at driving to continuously moving targets.

 

[Pinus contorta]

It’s an interesting argument.

I think it was Salford City Transport back in the 50’s decided to order their buses with the larger 9.6 litre engine over the smaller 7.4 litre unit.

Their thoughts were (I assume based on proven running with both), was that a larger engine being used lightly (not laboured), uses less fuel than a smaller engine working harder. It seemed to be the case too.

I’ve used your notch 3/4 reasoning in my professional road driving days and agree that accelerating harder gets to speed quicker where the engine then cruises.

However, in the case of a class 66 for example, it’s not quite as cut and dry. Notch 8 produces around 3000hp at the rail I think it is, where 7 produces 2300. But N8 uses 25% more fuel as the supercharger and turbo are both in.

You do get up to speed quicker, but I enables aren’t always that tightly timed and other late running trains could cause delays to you, so there’s more variables at play to make it a simple answer.

Charles Baroth , Salford City Transport, a visionary ahead of the game. Transformed the reliability & availability of vehicles in the fleet.

 

[bramling]

Yes the mileage is useful. When initially being installed onto the TMS screens on our 745/755 fleet the training school said that at long last you’ll all have an in-cab clock now as we know most of you will ignore any advice it gives you

Is the cynical view that DAS was essentially an attempt to sow the seeds of reducing the amount of driver route knowledge required, or is this a conspiracy theory too far? It does seem to have turned out to be a complete waste of time and money.

 

[Harpo]

It's part of the business case for ETCS that trains will operate more efficiently

While I’m a big fan of ETCS, I’m struggling to think where (except with ATO) that extra efficiency would come from. Even then, ATO’s efficiency is the capacity gain from the train driving itself harder than a human is allowed to, powering-up to the end of a movement authority for example.

 

[dk1]

Is the cynical view that DAS was essentially an attempt to sow the seeds of reducing the amount of driver route knowledge required, or is this a conspiracy theory too far? It does seem to have turned out to be a complete waste of time and money.

That has made me laugh. Crazy the way people read into things.

 

[DelW]

how much fuel does a train use carrying fuel around in a tank that wont bee needed. a post earlier in the thread said tanks are filled at the depot between 1200 and 2000 litres. if the train is doing 100 miles end to end and uses i dont know say 250 litres how much does it use to carry the extra fuel in the tank. if 100 miles was 250 litres and the tocs wanted better economical journeys would they be better putting less in a tank. Dont know how heavy a litre of fuel is but carrying enough for one journey and a small bit for diverts/delays would save fuel. Always thought thats how most airlines operated

Fuel weighs roughly a kilogram per litre, so 2000 litres would weigh around 2 tonnes, which is fairly insignificant in the context of train weights. Extra weight is much more significant to aircraft.

There would be a small fuel penalty from the extra energy needed to accelerate the weight of a full tank up to speed, or to move it uphill. That energy might be partially recovered by subsequent coasting, or might be lost through braking. I doubt whether the effects on overall fuel consumption would be detectable in practice.

 

[800301]

While I’m a big fan of ETCS, I’m struggling to think where (except with ATO) that extra efficiency would come from. Even then, ATO’s efficiency is the capacity gain from the train driving itself harder than a human is allowed to, powering-up to the end of a movement authority for example.

You wouldn’t necessarily have to brake as hard for restrictive signals as you’ll know exactly where your end of authority is and the blocks can be much shorter, the target speed would prevent acceleration and then braking cycles

 

[Harpo]

You wouldn’t necessarily have to brake as hard for restrictive signals as you’ll know exactly where your end of authority is and the blocks can be much shorter, the target speed would prevent acceleration and then braking cycles

Thanks. That makes sense. The shorter (i.e. more) block sections though will need extra funding on top of basic renewals costs. Current DfT parsimony suggests that could be a tough sell.

 

[notadriver]

It's part of the business case for ETCS that trains will operate more efficiently

It can actually impose a lower speed limit rather than just advise.

 

[RyanOPlasty]

I was told years ago that the pedal in my car that uses the most fuel is the brake. Logically, this is true, but planning ahead is required.

If you use the brake more, then you have put excess energy into the system. Coasting is better where possible, provided that the required timings can be achieved.

The conditions on the railway are less variable than on the road, so it should be easier to achieve a consistent and efficient power and coast strategy.


Where regenerative braking with electric traction is available, then the situation may be different.