Are Top Speeds Really Just the Recommended Speed?

[hexagon789]

I believe in a 390 it is 3.5mph above you get a TASS warning and 6mph above you get an intervention. I think 221 is 4.5mph and 5.5mph respectively. I need to double check this though.

Bit more leeway than I'd thought.

Not really to be honest unless you know the unit is particularly sensitive. Losing tilt is what you can call ‘fun’ for the passengers and catering crew especially on a few units that keep losing and gaining tilt every few minutes which causes a sudden and heavy brake application as speed needs to be reduced by 25 mph quickly before TASS starts screaming at you.

If that happens you have to reduce speed by 25mph within a set amount of time or the emergency brake applies then I presume?

 

[Strat-tastic]

That must be quite a pain if you allow the unit to just slip over the limit, because you don't get much leeway with TASS compared to ATP IIRC.

I've heard that the UAP is PRH so PEWYM.

 

[hexagon789]

I've heard that the UAP is PRH so PEWYM.

I'm sorry, I don't know what that means!

 

[Strat-tastic]

Unexplained abbreviation problem
Particularly relevant here
Please explain what you mean

 

[hexagon789]

Unexplained abbreviation problem
Particularly relevant here
Please explain what you mean

I wondered if that was meant to highlight that!

Sorry

TASS - Tilt Authorisation and Speed Supervision, a balise-based system used on the WCML which transmits data to Pendolinos and Super Voyagers telling them how much to tilt and the maximum permitted speed. If a train fails to pick up a transmission for whatever reason then tilting is disabled and the train limited to normal speeds.

ATP - Automatic Train Protection, fitted ro the Chiltern and Great Western Main Line, it monitors a trains speed and intervenes if a train is not slowing quickly enough to comply with speed restrictions or restrictive signal aspects.

IIRC - If I Remember Correctly.

 

[Strat-tastic]

I wondered if that was meant to highlight that!

Sorry

TASS - Tilt and Speed Supervision, a balise-based system used on the WCML which transmits data to Pendolinos and Super Voyagers telling them how much to tilt and the maximum permitted speed. If a train fails to pick up a transmission for whatever reason then tilting is disabled and the train limited to normal speeds.

ATP - Automatic Train Protection, fitted ro the Chiltern and Great Western Main Line, it monitors a trains speed and intervenes if a train is not slowing quickly enough to comply with speed restrictions or restrictive signal aspects.

IIRC - If I Remember Correctly.

T

Er I mean thanks

 

[hexagon789]

T

Er I mean thanks

YVW - You're very welcome

 

[PudseyBearHST]

Bit more leeway than I'd thought.



If that happens you have to reduce speed by 25mph within a set amount of time or the emergency brake applies then I presume?

If you’re not quick enough, you would get a TASS intervention. With the Claas 221, as mentioned earlier, you won’t get your brake back until the train has stopped fully.

I wondered if that was meant to highlight that!

Sorry

TASS - Tilt and Speed Supervision, a balise-based system used on the WCML which transmits data to Pendolinos and Super Voyagers telling them how much to tilt and the maximum permitted speed. If a train fails to pick up a transmission for whatever reason then tilting is disabled and the train limited to normal speeds.

ATP - Automatic Train Protection, fitted ro the Chiltern and Great Western Main Line, it monitors a trains speed and intervenes if a train is not slowing quickly enough to comply with speed restrictions or restrictive signal aspects.

IIRC - If I Remember Correctly.

TASS stands for Tilt Authorisation (and) Speed Supervision.

 

[hexagon789]

If you’re not quick enough, you would get a TASS intervention. With the Claas 221, as mentioned earlier, you won’t get your brake back until the train has stopped fully.

I was more meaning how long do you get and how hard do you have to brake.

TASS stands for Tilt Authorisation (and) Speed Supervision

Yes, I've made a bit of a typo on that trying to reply so quickly. Duly edited.

 

[PudseyBearHST]

I was more meaning how long do you get and how hard do you have to brake.



Yes, I've made a bit of a typo on that trying to reply so quickly. Duly edited.

I couldn’t give you an exact value but not more than a couple of seconds before TASS starts screaming. It’s particularly annoying with a Class 221 because the TASS display is not in direct view of the driver and you only get a little ‘beep’ when you lose tilt and so if you aren’t focusing, you won’t even realise you’ve lost tilt until TASS starts screaming.

Class 390: step 4 will do it
Class 221: hard to quantify as its variable power-brake controller but it’s heavy.

 

[Bald Rick]

Do the automatic braking systems activate when the train goes over it's "Maximum Speed" or just line speed?

So for example, would a 158 be able to do 100 in a 125 zone without a problem?

After the first few years of service, and some delightfully ‘exciting’ runs, all HSTs were fitted with speed governors that limited them to approx 128mph.

Losing tilt is what you can call ‘fun’ for the passengers and catering crew especially on a few units that keep losing and gaining tilt every few minutes which causes a sudden and heavy brake application as speed needs to be reduced by 25 mph quickly before TASS starts screaming at you.

I was on a 390 in the early days where the tilt failed as we on the first part of Weedon at 125. As a result we entered the second part at 125mph leaning the wrong way as the driver threw out the anchors. Now that was an experience! Pretty much everything on the tables made a sharp exit stage left.

 

[hexagon789]

I couldn’t give you an exact value but not more than a couple of seconds before TASS starts screaming. It’s particularly annoying with a Class 221 because the TASS display is not in direct view of the driver and you only get a little ‘beep’ when you lose tilt and so if you aren’t focusing, you won’t even realise you’ve lost tilt until TASS starts screaming.

I have visions of a piercing shrill emanating from the desk, when you lose tilt.

Class 390: step 4 will do it
Class 221: hard to quantify as its variable power-brake controller but it’s heavy.

Thank you. I wondered if you had to use Full Service or not, but I suppose even Step 4 is fairly heavy.

 

[Mutant Lemming]

Speeding was certainly rife on LU as recently as the 2000s. It was virtually standard practice on some sections to try and get the needle “off the clock”. On something like a 59 stock this would be 60 mph. Having said that, I forget what the actual official top speed of a 59 stock actually was.

Nowadays on-train monitoring equipment is virtually standard across LU, I think the only one which doesn’t have it is the Bakerloo. Have an incident and the download shows speeding and the driver will be in hot water, especially if someone like the ORR get involved.

With the 59s maybe but you wouldn't want to speed with a 72- apart from the lottery of the rheo their 'bouncyness' didn't agree with coping stones on platforms North of the Park (particularly Wembley Central)

 

[Llama]

Unless there is TPWS fitted in the vicinity (such as approaching a significant speed restriction), I don't believe there is anything to physically prevent a 158 from doing 100mph like that, no.

Not all trains have either speed limiters, nor systems to prevent such overspeeds.

TPWS doesn't work like that, the 'set-speed' at which thr emergency brake will apply is the same for all passenger trains. TPWS also doesn't prevent a train from exceeding the permissible speed per se. A few TPWS installations on approach to PSRs are set above the permissible speed on the approach to the restriction.

 

[Peter Mugridge]

I've definitely read that 4REPs were capable of far more than 90, definitely at least 100.

Somewhere I have a picture, albeit rather poor quality, showing a REP speedo with the needle jammed against the stop.

 

[Dieseldriver]

Unless there is TPWS fitted in the vicinity (such as approaching a significant speed restriction), I don't believe there is anything to physically prevent a 158 from doing 100mph like that, no.

Not all trains have either speed limiters, nor systems to prevent such overspeeds.

158s have nothing to physically prevent overspeeding. Aside from ERTMS/ATP/TASS fitted lines/traction there is generally nothing to prevent linespeed being exceeded. A TPWS activation/intervention doesn't necessarily mean the Driver was speeding at the time. It's purpose is to stop a train that is approaching a lower speed restriction or Red signal too fast. As an example, if a Driver is travelling at 90mph in a 90mph limit and is approaching a 40mph limit, if there is TPWS fitted on the approach and the Driver leaves their braking until the last minute and applies full service TPWS will almost definitely intervene/activate. This doesn't mean the Driver was speeding, it means the system has determined that their approach to the lower speed was too aggressive and so it intervenes to stop the train. Many TPWS activations have occurred where the train was well under the lower speed as it passed the commencement board.

 

[hexagon789]

TPWS doesn't work like that, the 'set-speed' at which thr emergency brake will apply is the same for all passenger trains. TPWS also doesn't prevent a train from exceeding the permissible speed per se. A few TPWS installations on approach to PSRs are set above the permissible speed on the approach to the restriction.

I know that, for a start I don't think I worded my earlier post very clearly perhaps. Secondly, I only meant that TPWS was about the only thing I could think of physically preventing a 158 getting to 100, if a brake application was triggered by TPWS on approach to a speed restriction.

As I understand it at certain locations with (I think 30% or greater) reductions in permissible speed TPWS grids may be fitted. These will trigger a brake application by measuring the time taken for a train to pass over the grids, if it is quicker than the preset speed an emergency brake application is triggered. The preset speed will be such that a train's speed would be reduced to less than the value of the upcoming restriction if an emergency brake is triggered.

Somewhere I have a picture, albeit rather poor quality, showing a REP speedo with the needle jammed against the stop.

What does the scale go up to in a 4REP, 100?

158s have nothing to physically prevent overspeeding. Aside from ERTMS/ATP/TASS fitted lines/traction there is generally nothing to prevent linespeed being exceeded. A TPWS activation/intervention doesn't necessarily mean the Driver was speeding at the time. It's purpose is to stop a train that is approaching a lower speed restriction or Red signal too fast. As an example, if a Driver is travelling at 90mph in a 90mph limit and is approaching a 40mph limit, if there is TPWS fitted on the approach and the Driver leaves their braking until the last minute and applies full service TPWS will almost definitely intervene/activate. This doesn't mean the Driver was speeding, it means the system has determined that their approach to the lower speed was too aggressive and so it intervenes to stop the train. Many TPWS activations have occurred where the train was well under the lower speed as it passed the commencement board.

That was my understanding of TPWS, even if my post doesn't make that clear.

 

[delticdave]

Mostly they would stick to 75 mph. But in my experience,156s were quite capable of 80 mph + and I have records of a 156/158 combo doing 86 mph on the downhill section from Hethersett to Trowse.

I don't have any formal records, but I do remember looking at a 156 speedo nudging 90 mph before Trowse + a 315 speedo
touching 88 mph eastbound on the fast line through Romford. (Both intermediate cabs, & the pair of 315's was working one of the Liv. St, Stratford, Harold Wood & all stations to Southend Vic. peak services back in the early '80's.

Said trains were usually rostered for a pair of 307's but one of the early evening services always produced 2 x315's.

I've also seen 92 mph on the last evening Liv. St to Southminster at Romford, but that was from a 'phone GPS, in a single Renatus 321.
The 1930 Norwich - Liv. St is a 12 car 321, quite interesting if you like fairground rides........

 

[Wychwood93]

Somewhere I have a picture, albeit rather poor quality, showing a REP speedo with the needle jammed against the stop.

I did have a REP at ~110 in the late 80's south of Winchester - the '~' to allow for the dodgy mileposts and subsequent more detailed distance information later. In the early REP era it was not unusual to have 100 down through Hinton Admiral. A chat with a driver re. the 110 elicited 'the speedo goes to 90, after that it is just guesswork' - fair play and similar in its own way to the 140 club on the GWR with unrestricted HSTs. The early runs with the 442's saw assorted speeds of ~110 east of Basingstoke and a 118 down through Eastleigh to stop at Parkway. The 442 brakes were (perhaps still are? - hopefully!) excellent - in a day of different driving they could, and I have figures from my own timings, stop from 90 in half a mile. Unlikely to happen now, although probably equally possible should someone give it a whirl. From another thread I recall a driver saying that he would hit Chippenham 'hard', around 60 at the ramp - probably on the up. 4-SUB stuff.

 

[BMIFlyer]

I’ve had a 155 down the bank from Micklefield to Church Fenton at 90mph many years ago.

 

[Llama]

Now that's stretching things, a 155 wouldn't get to 90 off Beachy Head...

 

[Sprinter156]

I've seen 156s doing 90 when they used to do Glasgow via Killwinning services.

 

[craigybagel]

Unless there is TPWS fitted in the vicinity (such as approaching a significant speed restriction), I don't believe there is anything to physically prevent a 158 from doing 100mph like that, no.

Not all trains have either speed limiters, nor systems to prevent such overspeeds.

The TfW 158s are all fitted with ERTMS. Even when running on non ERTMS fitted lines, the system will still prevent the units from going much over 90mph. There is also an option to tell the system that a 75mph unit is part of the formation, in which case it will limit the speed further.

I believe in a 390 it is 3.5mph above you get a TASS warning and 6mph above you get an intervention. I think 221 is 4.5mph and 5.5mph respectively. I need to double check this though.

Not really to be honest unless you know the unit is particularly sensitive. Losing tilt is what you can call ‘fun’ for the passengers and catering crew especially on a few units that keep losing and gaining tilt every few minutes which causes a sudden and heavy brake application as speed needs to be reduced by 25 mph quickly before TASS starts screaming at you.

I can remember it being great fun in my old job if you were providing the 1st class at seat service when tilt fails - first you get thrown sideways by the lack of tilt, then forwards when the brakes come on.....

 

[sarahj]

I've been in a 313 that noted as 75 doing over 80. Alas on a Southern route they don't run anymore. (I'm not the driver here BTW)

 

[hexagon789]

The TfW 158s are all fitted with ERTMS. Even when running on non ERTMS fitted lines, the system will still prevent the units from going much over 90mph. There is also an option to tell the system that a 75mph unit is part of the formation, in which case it will limit the speed further.

I knew I'd forgotten something else - ERTMS. So rather like ATP it can physically limit a unit to its top speed.

Does it need specifically input or does the system "know" a 158 is limited to 90?

 

[Bald Rick]

I knew I'd forgotten something else - ERTMS. So rather like ATP it can physically limit a unit to its top speed.

Does it need specifically input or does the system "know" a 158 is limited to 90?

It knows.

 

[BluePenguin]

In the anorak and ABC world it is widely held that Western Region 125s often ran at up to 135mph if they needed to make time. You cannot now of course.

Why could they not? At quieter times of day I would have thought it would be possible if there is no trains in front

 

[southern442]

I've been in a 313 that noted as 75 doing over 80. Alas on a Southern route they don't run anymore.

Given that the 508's used to run the LBG - Tonbridge fast services via Croydon, would there be a possibility of them reaching ~80 MPH at times?
I believe I once recorded a pendolino at around 129/130 coming down the WCML from Glasgow too.

 

[atraindriver]

<deleted>

 

[Jozhua]

Except on one of the 170/1s, where it hadn't cut in by the time I'd bottled it at 110...

Seems fun! Are there any risks involved with going over a train's maximum rated speed (On a section of track that has a higher speed limit than the trains)?