RIP Great western 125mph.... (IETs to have speed limiter automatically set)

[AM9]

But why, even if the limiter can’t accept imperial measurements, can’t it be set to 201.168km/h, which is the actual maximum permissible speed in this country?

For whose benefit is it to actually drive a metric train to a purely nominal imperial speed limit that was introduced as a marketing tool?

 

[507020]

For whose benefit is it to actually drive a metric train to a purely nominal imperial speed limit that was introduced as a marketing tool?

If the level of infrastructure maintenance is based on a maximum speed of 125mph, which will now never be reached again, then surely resources are being wasted somewhere.

If it can't accept imperial measurements its even less likely to be able to accept decimal ones. You could maybe reprogram it to accept a float (decimal figure) instead of an integer, but is it really necessary for such a small rounding error? The cost and effort of doing so doesn't seem worth it for a train traveling at a consistent speed to be able to cover an extra 193.6 yards in an hour. Realistically the only benefit for doing so is bragging rights, far more time will be lost during a journey due to other factors.

My question was actually mainly technical, with regards to whether the system is designed to accept a floating point or integer value. 201.168km/h may be a small rounding error of no detriment to reliability, but is it beneficial if speed can only be incremented in values of whole kilometres, particularly at lower or single figure speeds?

 

[hexagon789]

If the level of infrastructure maintenance is based on a maximum speed of 125mph, which will now never be reached again, then

Because somehow the level of maintenance can be reduced for a maximum of 124.89mph...?!?

 

[507020]

Because somehow the level of maintenance can be reduced for a maximum of 124.89mph...?!?

No, it can’t, so not achieving the maximum speed of 125mph is a waste of resources.

 

[XAM2175]

Because somehow the level of maintenance can be reduced for a maximum of 124.89mph...?!?

I look forward to seeing NR reap the rewards realised by surrendering that oh-so-wasteful 0.11 mph

My question was actually mainly technical, with regards to whether the system is designed to accept a floating point or integer value. 201.168km/h may be a small rounding error of no detriment to reliability, but is it beneficial if speed can only be incremented in values of whole kilometres, particularly at lower or single figure speeds?

Where is the benefit to allowing smaller increments?

 

[AM9]

Where is the benefit to allowing smaller increments?

It allows this bizarre discussion to continue for a few more posts.

 

[gimmea50anyday]

Do Voyagers reach 125mph Reading-Didcot?

I have seen 132mph reading on the TMS when Old Oak Common drivers were wanting to make time up and on the run home!

And it's probably TPEs fault that this is being done in the first place after one of their drivers had a little oopsie on the race track between York and Northallerton...

Whilst it won't affect schedules I think its a shame, and completely the fault of the TPE driver who cocked it up for everyone.

but sod what the drivers think lets all have a knee jerk reaction to one driver up north who couldn't

right, in defence of my driver colleague who attained the speed record unintentionally…..

it was a number of factors that allowed him to reach 148mph, and the second he realised what he was doing he stopped the train and self-reported it.

TPE 802s are electrically the same as GWR 802s and have the wiring looms and the programming in the TMS to expect instructions from GWR ATP which includes speed limit settings. Of course that information isn't provided because theres no ATP, So there hasn't been any speed limiter incorporated in to the other fleets in Lieu of GWR-APT. Speed Set can provide a speed limiter function, but its a form of cruise control, not a speed limiter. It needs to be set within the TMS. This was done when my driver colleague overspeeded, however it wasn't acknowledged by the TMS so although it appeared to be set, it wasn’t active. There was also a phase of driver training that taught drivers to drive on the speed set. A good idea in theory but the ability to maintain appropriate speed was lost as a result. This was binned after the speeding incident. The incident took place at night on a stretch of straight high speed running line and reference points are few and far between. Disorientation also played a part as the OHLE stanchions passing repetitively can have a hypnotising effect.

so lessons were learned and adopted by all AT300 operators, not just TPE. my driver colleague was just one individual but he wasn't the only one to have done this so don't hang one individual out to dry and blame him. This was the result of poor train design and mistakes in training Programmes. He did everything by the book when he came clean and self reported, something he was credited for. He admitted he was focussed on the road ahead and not the speed gauge and believed the TMS was showing 125 as his actual speed but it was showing the desired speed setting plus it was on the night setting so the screen was dim. He still drives, he is now the butt of many jokes and name ribbing including speeding bullet, bullet train, speedy gonzales, but with a wry smile he can also say he is the fastest driver on TPE!

 

[Trainbike46]

Is it true the dutch have a system where a display tells the driver to obey a certain speed to keep a distance from the train in front rather than obeying signals

The Dutch? No. They have a system called ATB that tells the driver the maximum speed for the block they're in (with some limitations), but it still uses fixed blocks and lineside signals. TVM in France and LZB in Germany both allow fully in-cab signalling, as will ECTS which replaces them and is being deployed here too - but even then moving-block operation is a long long way away.

I believe there is a system that tells the driver the distance to the previous train as well as the speed or something, which isn't part of the signalling system but in place on top of it so the drivers can avoid hitting yellows in the ATB signalling system. I don't know the details of how that works though...

 

[TurboMan]

I believe there is a system that tells the driver the distance to the previous train as well as the speed or something, which isn't part of the signalling system but in place on top of it so the drivers can avoid hitting yellows in the ATB signalling system. I don't know the details of how that works though...

Sounds much like C-DAS (connected driver advisory system) which as well as all the usual DAS data (timetabled stops etc.) uses live info from the signalling system to advise the driver to drive at a lower speed if there is a train ahead, or a junction is not set.

 

[Stigy]

Why not set it to 126mph?

 

[XAM2175]

so lessons were learned and adopted by all AT300 operators, not just TPE. my driver colleague was just one individual but he wasn't the only one to have done this so don't hang one individual out to dry and blame him. This was the result of poor train design and mistakes in training Programmes. He did everything by the book when he came clean and self reported, something he was credited for. He admitted he was focussed on the road ahead and not the speed gauge and believed the TMS was showing 125 as his actual speed but it was showing the desired speed setting plus it was on the night setting so the screen was dim. He still drives, he is now the butt of many jokes and name ribbing including speeding bullet, bullet train, speedy gonzales, but with a wry smile he can also say he is the fastest driver on TPE!

That all sounds fair enough. Was it the case that the TMS was showing speed set 125 when the speed set wasn't active, or that it was "active" but not actually working?

I believe there is a system that tells the driver the distance to the previous train as well as the speed or something, which isn't part of the signalling system but in place on top of it so the drivers can avoid hitting yellows in the ATB signalling system. I don't know the details of how that works though...

Sounds much like C-DAS (connected driver advisory system) which as well as all the usual DAS data (timetabled stops etc.) uses live info from the signalling system to advise the driver to drive at a lower speed if there is a train ahead, or a junction is not set.

Ah yes, NS do have a fairly sophisticated DAS that does indeed provide real-time data on signalling and service regulation, etc etc. I think it's also capable of controlling the PIS on newer trains, but don't quote me on that.

 

[nlogax]

Can anybody explain why limiters being set to just a shade under 125mph is any sort of major deal? I genuinely don't understand the angst from some on this thread.

 

[irish_rail]

Can anybody explain why limiters being set to just a shade under 125mph is any sort of major deal? I genuinely don't understand the angst from some on this thread.

Its not the speed, its the increase in driver "underload". Rather than have to concentrate on keeping his or her train at 125mph, it is now very easy to open her up passing North Pole depot and not need to do anything much until approaching Reading. This is obviously not good.

 

[AM9]

Can anybody explain why limiters being set to just a shade under 125mph is any sort of major deal? I genuinely don't understand the angst from some on this thread.

It seems to be a problem with the few who are obsessed with high numbers, and the prestige in claiming that 'they were there'. All this twaddle about limiting trains to a speed that is less than 0.09% less than 'inferior' than an outdated imperial speed marketed in the 1970s will damage the viability of the railway.

 

[Dai Corner]

It seems to be a problem with the few who are obsessed with high numbers, and the prestige in claiming that 'they were there'. All this twaddle about limiting trains to a speed that is less than 0.09% less than 'inferior' than an outdated imperial speed marketed in the 1970s will damage the viability of the railway.

I doubt if the speedos are that accurate anyway!

 

[AM9]

I doubt if the speedos are that accurate anyway!

That had crossed my mind as well. Not only the on-train speedos which would be sensitive to whell wear status, but commercial GPS is also subject to inaccuracies, especially when receiving sattelites from within an aluminium or steel tube, moving under catenary and whatever bridges etc., happen to be there.

 

[Dai Corner]

That had crossed my mind as well. Not only the on-train speedos which would be sensitive to whell wear status, but commercial GPS is also subject to inaccuracies, especially when receiving sattelites from within an aluminium or steel tube, moving under catenary and whatever bridges etc., happen to be there.

There are speedometers based on the Doppler effect, but they'd be overkill for this application I think.

 

[TurboMan]

Its not the speed, its the increase in driver "underload". Rather than have to concentrate on keeping his or her train at 125mph, it is now very easy to open her up passing North Pole depot and not need to do anything much until approaching Reading. This is obviously not good.

You don't have to do that though, you could continue to drive the train as if the speed limiter didn't exist, using power and brake to keep it at 124, rather than sticking the CPBC in max and leaving the train to it.

== Doublepost prevention - post automatically merged: 28 Sep 2022 ==

There are speedometers based on the Doppler effect, but they'd be overkill for this application I think.

80x are fitted with Dopplers as they're ETCS fitted (all ETCS-fitted traction uses a Doppler radar). On GWR, the speed is displayed on the ATP speedo as everything runs with ATP protection, but switching the ETCS/BR-ATP selection switch on the cab back wall to 'ETCS' disables ATP and displays the speedo on the ETCS DMI, which I assume would use the Doppler. I don't know whether the Doppler provides the speed signal for the ATP speedo though.

 

[Fincra5]

You don't have to do that though, you could continue to drive the train as if the speed limiter didn't exist, using power and brake to keep it at 124, rather than sticking the CPBC in max and leaving the train to it.

== Doublepost prevention - post automatically merged: 28 Sep 2022 ==


80x are fitted with Dopplers as they're ETCS fitted (all ETCS-fitted traction uses a Doppler radar). On GWR, the speed is displayed on the ATP speedo as everything runs with ATP protection, but switching the ETCS/BR-ATP selection switch on the cab back wall to 'ETCS' disables ATP and displays the speedo on the ETCS DMI, which I assume would use the Doppler. I don't know whether the Doppler provides the speed signal for the ATP speedo though.

Doppler Radars, usually, work in Tandem with the classic Odometer - used for the normal Speedo.

 

[irish_rail]

You don't have to do that though, you could continue to drive the train as if the speed limiter didn't exist, using power and brake to keep it at 124, rather than sticking the CPBC in max and leaving the train to it.

== Doublepost prevention - post automatically merged: 28 Sep 2022 ==


80x are fitted with Dopplers as they're ETCS fitted (all ETCS-fitted traction uses a Doppler radar). On GWR, the speed is displayed on the ATP speedo as everything runs with ATP protection, but switching the ETCS/BR-ATP selection switch on the cab back wall to 'ETCS' disables ATP and displays the speedo on the ETCS DMI, which I assume would use the Doppler. I don't know whether the Doppler provides the speed signal for the ATP speedo though.

That wouldn't work as the speedo sits at 123 or 124 now, so in order to actually "drive it" would need to be looking at keeping it at 120mph (the main speedo isn't accurate enough to work with 121 122 mph etc). 120 admittedly wouldn't lose much time, but if the Bristol driver drives it like that leaving Paddington at xx02 and I'm following at xx04 then I'm gonna be more likely catching him up, certainly on the approach to Reading.