Info about a speed sign

[KeithHC]

On the Gloucester Bristol line just south of the Charfield loops is a speed sign. In fact there are two speeds shown one for 90 and one that says HST 100. Does the HST 100 only apply to HST sets or does it also apply to Cross Country 220 and GWR 800.

 

Keith

[Michael Hodgson]

https://www.railsigns.uk/sect13page3/sect13page3.html

 

[Mike_Walker]

1 hour ago, KeithHC said:

On the Gloucester Bristol line just south of the Charfield loops is a speed sign. In fact there are two speeds shown one for 90 and one that says HST 100. Does the HST 100 only apply to HST sets or does it also apply to Cross Country 220 and GWR 800.

 

Keith

Yes, in this instance.  HST refers to a whole group of classes not simply the classic HST.  There is often a note in the Sectional Appendix specifying which types can run at the HST speed at a particular location.  It is usually based on braking performance rather than speed. 

[96701]

Stolen from the Sectional Appendix for Western. All are available here:

 

https://www.networkrail.co.uk/industry-and-commercial/information-for-operators/national-electronic-sectional-appendix/

 

"HST Class 91 locomotive with mark 4 vehicles and DVT, classes 80x 158, 159, 165, 166, 168, 170, 171, 172, 175, 180, 220, 221, 222, 253, 254 and 373"

[KeithHC]

Thanks for all the reply’s lots to look up and have a read. It is still great to see an HST set nearly at full chat.......

 

Keith

[Wickham Green too]

Hmmmm ............... class 91 & Eurostar were never particularly common in Gloucestershire.

[pheaton]

12 hours ago, Mike_Walker said:

Yes, in this instance.  HST refers to a whole group of classes not simply the classic HST.  There is often a note in the Sectional Appendix specifying which types can run at the HST speed at a particular location.  It is usually based on braking performance rather than speed. 

 

8 hours ago, 96701 said:

Stolen from the Sectional Appendix for Western. All are available here:

 

https://www.networkrail.co.uk/industry-and-commercial/information-for-operators/national-electronic-sectional-appendix/

 

"HST Class 91 locomotive with mark 4 vehicles and DVT, classes 80x 158, 159, 165, 166, 168, 170, 171, 172, 175, 180, 220, 221, 222, 253, 254 and 373"

the giveaway is they all have disc brakes which have a higher braking performance than clasp brakes

[Edwin_m]

4 hours ago, Wickham Green too said:

Hmmmm ............... class 91 & Eurostar were never particularly common in Gloucestershire.

However there is or was an open access proposal to use them on London-Swansea, which passes through ceremonial Gloucestershire and the unitary authority of South Gloucestershire.  

[Wickham Green too]

4 hours ago, pheaton said:

 

the giveaway is they all have disc brakes which have a higher braking performance than clasp brakes

Hasn't pretty well everything else got disc brakes nowadays tho' ??!?

[Mike_Walker]

2 hours ago, Wickham Green too said:

Hasn't pretty well everything else got disc brakes nowadays tho' ??!?

Passenger stock yes.  But braking performance varies between types. 

 

[Edwin_m]

4 hours ago, Wickham Green too said:

Hasn't pretty well everything else got disc brakes nowadays tho' ??!?

Pacers and 150-156s don't.  Rather surprisingly 700s have tread brakes on some bogies, but I assume can still meet the braking standard required for discs.  

Edited April 30, 2021 by Edwin_m

[Ken.W]

4 hours ago, Edwin_m said:

Pacers and 150-156s don't.  Rather surprisingly 700s have tread brakes on some bogies, but I assume can still meet the braking standard required for discs.  

 

Well, in my experience of the things Pacers wouldn't , reliably, meet any braking standard!

 

As I understood it, the differential speed limits were also to do with the train's track forces, ie axle loadings and ride quality. HSTs with their bogie mounted traction motors are easier on the track than traditional locos with axle-hung motors.

There's other varieties of differential speeds, such as 'SP' which applies to the 'Sprinter' classes (but not the Pacers!)

[Edwin_m]

16 minutes ago, Ken.W said:

 

Well, in my experience of the things Pacers wouldn't , reliably, meet any braking standard!

 

As I understood it, the differential speed limits were also to do with the train's track forces, ie axle loadings and ride quality. HSTs with their bogie mounted traction motors are easier on the track than traditional locos with axle-hung motors.

There's other varieties of differential speeds, such as 'SP' which applies to the 'Sprinter' classes (but not the Pacers!)

It's a bit lost in the mists of time, but as I understand it SP was related specifically to low track forces, and those for Sprinters would be much lower than for HSTs.  It allowed speeds to be increased for 158s in particular without doing much work to the track, and I believe SP speeds above 75mph were also based on braking distances with disc brakes, since the tread-braked Sprinters are limited to that speed.  I believe the policy is to replace SP by MU differentials where possible.  

[big jim]

There are a couple of SP speed restriction board on a couple of curves on the chilterns at high Wycombe and aynho jn that don’t apply to certain sprinters!

 

if your in a 165/168 etc the speeds don’t apply but if you have a ‘sprinter’ with a centre gangway such as 156 or 158  then you must go at the slower SP speed as there are signals on the curves that are obscured by the centre gangway 

 

as for HST speeds, after Solihull heading toward Marylebone then the loco hauled chiltern services (class 68 and previously 67) adhere to the HST speeds 

[Michael Hodgson]

6 hours ago, Edwin_m said:

Pacers and 150-156s don't.  

Do they count as passenger stock? 

I think those aberrations are unfit for livestock.

[NorthEndCab]

1 hour ago, Edwin_m said:

It's a bit lost in the mists of time, but as I understand it SP was related specifically to low track forces, and those for Sprinters would be much lower than for HSTs.  It allowed speeds to be increased for 158s in particular without doing much work to the track, and I believe SP speeds above 75mph were also based on braking distances with disc brakes, since the tread-braked Sprinters are limited to that speed.  I believe the policy is to replace SP by MU differentials where possible.  

I know between Manton and Syston Jn the differential is higher for sprinters. 

[Mike_Walker]

12 hours ago, big jim said:

There are a couple of SP speed restriction board on a couple of curves on the chilterns at high Wycombe and aynho jn that don’t apply to certain sprinters!

 

if your in a 165/168 etc the speeds don’t apply but if you have a ‘sprinter’ with a centre gangway such as 156 or 158  then you must go at the slower SP speed as there are signals on the curves that are obscured by the centre gangway 

 

as for HST speeds, after Solihull heading toward Marylebone then the loco hauled chiltern services (class 68 and previously 67) adhere to the HST speeds 

Here's a picture of the speed boards mentioned, or least the up direction AWIs for them between West Wycombe and High Wycombe.

 

 

When they went up they caused some astonishment not least to Chiltern's drivers as no "Sprinters" are scheduled to use the line.  Questions were asked by Chiltern management and the answer came back it was to allow for operating Class 158s over the route.  Some will remember that around the time Wrexham & Shropshire was being set up there was a rival plan put forward by Arriva Trains Wales to run a service from Aberystwyth to Marylebone which would have used 158s.  The issue was that with their gangwayed cabs there was thought to be reduced signal sighting around the curves through High Wycombe station compared to say a 165 or 168 hence a lower speed was posted under the SP category.  There is a similar restriction on the down line approaching Aynho Junction for the same reason.

 

The 60 PSR applies to all other passenger trains whilst 35 applies to freight trains.

 

The irony was that by the time the signs went up the Arriva plan had been abandoned.

 

 

Edited May 1, 2021 by Mike_Walker
Additional details added.

[big jim]

I know a chiltern driver took a london midland gangwayed 172/3 unit to Marylebone when they were first introduced and being tested 

 

The 196 units I’m involved with testing take MU (multiple unit) speeds as opposed to SP speeds 

[Edwin_m]

5 hours ago, big jim said:

The 196 units I’m involved with testing take MU (multiple unit) speeds as opposed to SP speeds 

I think the Marches line was one of those that got SP differentials in Regional Railways days.  Are they being, or have they been, changed for MU ones?  

[Ncarter2]

The WCML is an interesting one, it has the EPS speeds and normal PSR speeds. 
EPS- enhanced permissible speed, applies to the Pendolino and Tilting Voyager fleets, providing the TASS system is operating. Even the EPS speeds have some differentials on one sign, the lower speed over a higher speed relates to the Voyagers EPS and Pendolino EPS ( Pendo’s can go faster in places due to the greater Tilt).