Class 80x driving question (possibly others too)

Egg Centric · 11 Feb 2024

It is my understanding that 80xs are currently software limited to 124 mph. Is it therefore an acceptable driving technique on 125mph stretches to just open the throttle up and let the limiter take care of things or is the driver expected to proactively keep the speed under control him or herself?

This is probably a general question as I know many trains have limiters most of which I think are adjustable ones; in the latter case is it also fine for a driver who has set a limit to just whack on max throttle or are they expected to control the speed through the throttle with the limiter acting as a backstop?

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janahan · 11 Feb 2024

I don't know the answer to this, but taking cars as an example (those which have selectable speed limiters) this can be risky if the brakes are not also controlled. My wife's astra does not, so whilst the engine may stop applying any power after hitting the set speed, if you are going downhill, you may still accelerate past the set speed, therefore not a great idea to hold the accelerator down. My mercedes on the other hand will actively apply braking too if needed and generally is reliable to hold the accelerator.

Not sure if the limiters on trains (I belive some have selectable limiters) also control braking, and like cars may vary model to model.

irish_rail · 11 Feb 2024

It is quite acceptable to leave the power wide open on 125mph track and the train will sit at 124mph. I don't know of any drivers now who keep the train purposely at 124mph through "driving". In some ways this has now led to driver underload , and one problem is coming away from 124mph running to lower speed track (say the B and H) and forgetting you actually need to control your speed! For me it has made my life easier, though probably not a better driver for it. It was a knee jerk reaction to a problem that doesn't really exist (after a TPE driver accidentally hit 140mph or similar). What should have been done was the limiter set to say 128mph, to prevent a potential incident , but still requiring the driver to need to actually drive the train.

Also to add, the limiter is useless on gradients, ie you will still speed if you let it go on steep gradients, which is why no one bothers using it for the linespeeds in Devon and Cornwall for example. Infact as a result of this , it means there is still one place on the Western where 125mph is regularly achieved, Dauntsey Bank.

800301 · 11 Feb 2024

irish_rail said:
It is quite acceptable to leave the power wide open on 125mph track and the train will sit at 124mph. I don't know of any drivers now who keep the train purposely at 124mph through "driving". In some ways this has now led to driver underload , and one problem is coming away from 124mph running to lower speed track (say the B and H) and forgetting you actually need to control your speed! For me it has made my life easier, though probably not a better driver for it. It was a knee jerk reaction to a problem that doesn't really exist (after a TPE driver accidentally hit 140mph or similar). What should have been done was the limiter set to say 128mph, to prevent a potential incident , but still requiring the driver to need to actually drive the train.

Also to add, the limiter is useless on gradients, ie you will still speed if you let it go on steep gradients, which is why no one bothers using it for the linespeeds in Devon and Cornwall for example. Infact as a result of this , it means there is still one place on the Western where 125mph is regularly achieved, Dauntsey Bank.

On the GWR units I don’t see the point as ATP would give you a friendly reminder anyway at 128mph and a brake application at 131mph

Kneedown · 11 Feb 2024

On the 360s, where we are allowed to do 110mph north of Bedford, it's perfectly acceptable to let the limiter do it's thing, and it does it well, with no speed creep even going down Sharnbrook.

irish_rail · 11 Feb 2024

800301 said:
On the GWR units I don’t see the point as ATP would give you a friendly reminder anyway at 128mph and a brake application at 131mph

Yes this is how it was in HST days , and the driver still had to keep the speed at 125mph. You didn't just routinely let it creep up to 128mph as you know that where you downloaded it wouldn't look good!

dan4291 · 11 Feb 2024

On the 80x stock I drive the speed limiter defaults to 125mph and can't be switched off or increased over this amount. This was brought in after TPE and LNER both had overspeed incidents around 145mph. Perfectly acceptable to leave the power on and let the limiter do its thing.

janahan · 11 Feb 2024

dan4291 said:
On the 80x stock I drive the speed limiter defaults to 125mph and can't be switched off or increased over this amount. This was brought in after TPE and LNER both had overspeed incidents around 145mph. Perfectly acceptable to leave the power on and let the limiter do its thing.

The question I was trying to imply is does the limiter on 80x also control the brakes as well as the traction, so will limit even when going downhill? In cars you have standard (no braking) and active (controls braking) so you could hold the accelerator and it will not exceed a limit regardless of the gradient.

On a 80x can you do the same or do you have to be cautious about downhill gradients, where without braking it could still go beyond the limit thanks to gravity?

dan4291 · 11 Feb 2024

janahan said:
The question I was trying to imply is does the limiter on 80x also control the brakes as well as the traction, so will limit even when going downhill? In cars you have standard (no braking) and active (controls braking) so you could hold the accelerator and it will not exceed a limit regardless of the gradient.

On a 80x can you do the same or do you have to be cautious about downhill gradients, where without braking it could still go beyond the limit thanks to gravity?

The limiter also controls the brakes, at least on the 80x I sign.

Topological · 11 Feb 2024

This is an interesting insight. It does beg the question of whether trains could have the equivalent of cruise control. Further, whether that would then just mean settings for line speed and then whether the whole thing could be automated.

Of course, the answer is yes, the whole thing can be done automatically like planes. Planes will even land themselves on any runway in inclement weather so a train on a dedicated track is much more straightforward.

Planes did not get rid of pilots, so likewise I do not see the technology replacing a driver. It does beg the question of what can be realistically achieved.

Towers · 11 Feb 2024

Topological said:
This is an interesting insight. It does beg the question of whether trains could have the equivalent of cruise control. Further, whether that would then just mean settings for line speed and then whether the whole thing could be automated.

Of course, the answer is yes, the whole thing can be done automatically like planes. Planes will even land themselves on any runway in inclement weather so a train on a dedicated track is much more straightforward.

Planes did not get rid of pilots, so likewise I do not see the technology replacing a driver. It does beg the question of what can be realistically achieved.

I would imagine that any sensible assessment of having an ‘auto pilot’ system would be thrown out in short order due to the obvious risk of driver distraction and underload. You need a driver to be alert in order to respond to restrictive signals and any out of course incidents that might arise, I can’t see “leave the throttle wide open and doze off” being very popular!

It’s different with a road vehicle as the driver still has to steer, as well as monitor what the rest of the traffic is doing, both of which maintain a level of attentiveness and engagement by default (although plenty do clearly drift off a bit when on the motorway with cruise on); at the other end of the scale it’s different for an aeroplane because it’s flying a preset route & altitude etc and is very highly unlikely to crash into anything, and so the flight crew need only to keep an eye on things for the majority of the flight. A train sits in the middle with arguably the worst of both worlds, where a driver has no need to steer and can go for reasonably long periods without needing to touch the controls, but at the same time needs to remain constantly alert throughout.

800001 · 11 Feb 2024

dan4291 said:
On the 80x stock I drive the speed limiter defaults to 125mph and can't be switched off or increased over this amount. This was brought in after TPE and LNER both had overspeed incidents around 145mph. Perfectly acceptable to leave the power on and let the limiter do its thing.

Where was the LNER over speed at nearly 145? Not heard about that one?

Starmill · 12 Feb 2024

Topological said:
This is an interesting insight. It does beg the question of whether trains could have the equivalent of cruise control. Further, whether that would then just mean settings for line speed and then whether the whole thing could be automated.

It's not really the same as cruise control in a road vehicle because it's still "active" rather than passive, but doesn't some rolling stock already have a 'hold' button?

Topological · 12 Feb 2024

Towers said:
I would imagine that any sensible assessment of having an ‘auto pilot’ system would be thrown out in short order due to the obvious risk of driver distraction and underload. You need a driver to be alert in order to respond to restrictive signals and any out of course incidents that might arise, I can’t see “leave the throttle wide open and doze off” being very popular!

It’s different with a road vehicle as the driver still has to steer, as well as monitor what the rest of the traffic is doing, both of which maintain a level of attentiveness and engagement by default (although plenty do clearly drift off a bit when on the motorway with cruise on); at the other end of the scale it’s different for an aeroplane because it’s flying a preset route & altitude etc and is very highly unlikely to crash into anything, and so the flight crew need only to keep an eye on things for the majority of the flight. A train sits in the middle with arguably the worst of both worlds, where a driver has no need to steer and can go for reasonably long periods without needing to touch the controls, but at the same time needs to remain constantly alert throughout.

Thanks for the response.

It is an interesting one though, because presumably if something does come into view at a high speed that would require some form of quick reaction it is unlikely that there is very much that can be done apart from emergency braking. Whether that emergency braking can avert much I am not sure, that depends on the situation I guess.

Everything else (signals etc) are presumably all interlocked and therefore could be handled by the train knowing the speed for where it was.

Egg Centric · 12 Feb 2024

(I may now reveal my agenda - I am pleased to learn I was doing the right thing on Train Sim World 4 :lol:

800Travel · 12 Feb 2024

Egg Centric said:
(I may now reveal my agenda - I am pleased to learn I was doing the right thing on Train Sim World 4

I’ve often found I can get to 126 and above on TSW4 though on the 801

Egg Centric · 12 Feb 2024

800Travel said:
I’ve often found I can get to 126 and above on TSW4 though on the 801

Absolutely but I'm not bothered about that, I just want to drive it in as realistic a way as I can working around the sim limitations which are bluntly myriad. If the "real thing" would limit it to 124 on level or almost level ground that's good enough for me

Every train sim player needs to decide what they're gonna compromise on unfortunately...

Irascible · 12 Feb 2024

Topological said:
Planes will even land themselves on any runway in inclement weather

As an aside no, they need a certain category of ILS kit - I think regulations wise it's Cat IIIa but also I think you don't *need* that spec from a technical point of view. Either way you need ground based precision radio gear, planes can't just autoland on a random bit of straight tarmac.

Trains knowing the route would add a whole bunch of benefits even if they didn't drive themselves.

Towers · 12 Feb 2024

Topological said:
Thanks for the response.

It is an interesting one though, because presumably if something does come into view at a high speed that would require some form of quick reaction it is unlikely that there is very much that can be done apart from emergency braking. Whether that emergency braking can avert much I am not sure, that depends on the situation I guess.

Everything else (signals etc) are presumably all interlocked and therefore could be handled by the train knowing the speed for where it was.

No doubt one day the dreaded AI will inevitably be inflicted upon the railway to some extent, but in all honesty there are little if any benefits to that over a well trained and observant human being in this particular application; there are also pitfalls of course, see the various “self driving car” accidents in the US etc.

Automatically driven Tube lines retain some element of human control, as does even the highly publicised “robot” Docklands Light Railway. And these are ‘metro’ systems, operating on largely self contained and well protected infrastructure away from the multude of much greater hazards present on the “big railway”. I’m afraid I am firmly in the “not in my lifetime” camp, and very much hope I’m proved right on that one!

irish_rail · 12 Feb 2024

dan4291 said:
The limiter also controls the brakes, at least on the 80x I sign.

Really?! Out of interest which 80x do you sign? On GWR the limiter most certainly does not affect the braking, purely the amount of power applied, as , like I say, it's useless on gradients as the train speed will just pick up anyway. I'm interested to know if perhaps a later generation of 80x is different to the GWR stuff....

800301 · 12 Feb 2024

irish_rail said:
Really?! Out of interest which 80x do you sign? On GWR the limiter most certainly does not affect the braking, purely the amount of power applied, as , like I say, it's useless on gradients as the train speed will just pick up anyway. I'm interested to know if perhaps a later generation of 80x is different to the GWR stuff....

I was told that on electric they can brake themselves but not on Diesel, I’ve not seen it personally yet

dan4291 · 12 Feb 2024

800001 said:
Where was the LNER over speed at nearly 145? Not heard about that one?

It was sometime in 2021 north of York so I heard, very similar circumstances to the TPE overspeed incident.

cjmillsnun · 12 Feb 2024

Thought the other overspeed was Lumo rather than LNER

TurboMan · 12 Feb 2024

800301 said:
I was told that on electric they can brake themselves but not on Diesel, I’ve not seen it personally yet

In theory, the speed limiter will apply the brake when dynamic braking is available. On 800 that is only in electric mode, on 802 it is in both diesel and electric (as 802 has rheostatic braking in diesel mode).

800001 · 12 Feb 2024

dan4291 said:
It was sometime in 2021 north of York so I heard, very similar circumstances to the TPE overspeed incident.

Very much need to me if that’s the case.

notadriver · 12 Feb 2024

After spending miles on the limiter at an indicated 124 mph sometimes 125 mph, driving a coach at the limited 62 mph seems very slow.

craigybagel · 12 Feb 2024

I was quite amused to read in the Class 67 training material that allegedly the power will cut out at 127mph and the brakes will kick in at 130mph. Outside of testing when first built I doubt those protections have ever actually been used in anger!

197s have a limiter that cuts the power if you go over 101mph - it's quite a sharp jolt when it kicks in so it gives a much smoother ride if you hold it at 99/100 manually and make sure it doesn't creep over 100 if the gradient eases.

irish_rail · 12 Feb 2024

TurboMan said:
In theory, the speed limiter will apply the brake when dynamic braking is available. On 800 that is only in electric mode, on 802 it is in both diesel and electric (as 802 has rheostatic braking in diesel mode).

I'm pretty sure the reality is different as I frequently hit 125mph going down Dauntsey bank, which surely wouldn't happen if the brakes where activating.

Dren Ahmeti · 12 Feb 2024

Irascible said:
As an aside no, they need a certain category of ILS kit - I think regulations wise it's Cat IIIa but also I think you don't *need* that spec from a technical point of view. Either way you need ground based precision radio gear, planes can't just autoland on a random bit of straight tarmac.

Trains knowing the route would add a whole bunch of benefits even if they didn't drive themselves.

Off topic, but actually planes can autoland with a Cat I ILS, just needs to be monitored by the PF, and ready to respond instantly if the sensitive area is infringed on, as it’s not “protected” like a Cat II/Cat III ILS is under LVPs.

class ep-09 · 12 Feb 2024

janahan said:
The question I was trying to imply is does the limiter on 80x also control the brakes as well as the traction, so will limit even when going downhill? In cars you have standard (no braking) and active (controls braking) so you could hold the accelerator and it will not exceed a limit regardless of the gradient.

On a 80x can you do the same or do you have to be cautious about downhill gradients, where without braking it could still go beyond the limit thanks to gravity?

The limiter will apply “brakes” in electric mode for 800 class.
The traction motors will apply dynamic braking to slow train down if going downhill .

In diesel mode , if going downhill train will accelerate past the speed selected on the limiter.

802 should in theory use dynamic / regenerative braking to maintain speed in both diesel and electric mode.

Class 80x driving question (possibly others too)

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