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Short HST Formations


JohnR
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Shortest I've seen is:

<Power car| <Power car| |Power car>

It was travelling through Bristol Temple Meads to turn a power car for St Phillips Marsh depot (came out of the east end of the depot, through Temple Meads towards Bedminster, reverse back into the West end of St Phillips Marsh)

 

I have also seen 2+5 and 2+7 formations.

 

Will

 

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9 minutes ago, WillCav said:

Shortest I've seen is:

<Power car| <Power car| |Power car>

It was travelling through Bristol Temple Meads to turn a power car for St Phillips Marsh depot (came out of the east end of the depot, through Temple Meads towards Bedminster, reverse back into the West end of St Phillips Marsh)

 

I have also seen 2+5 and 2+7 formations.

 

Will

 

 

I was thinking of the official short HST sets being used by those operators. GWR call them "Castles" while for ScotRail its Inter7City. 

 

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Still settling down and possibly changed daily.  I haven't noticed a slam-door rake in use recently though so they might have finished.  

 

The shortest passenger-carrying HST formation of all-time was the single power car which made it to Par after detaching from a failed (derailed?) set on the Newquay branch.  The passengers were conveyed in the former guard's van.

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Taking info from the last 8 months Rail Express, alot from the derogations list as they are still slam-door and so non compliant.

 

Scotrail sets

HA01 - 41124-42256-42255-44029

HA02 - 41144-42032-42295-44039

HA03 - 41104-42208-42206-44066

HA04 - 41130-42325-42267-44032 (disbanded as of 26/01)

HA05 - 41022-42010-42030-44010

HA06 - 41158-42129-42200-44086

HA17 - 40610-42360-42551-42252

HA18 - 42293-42553-42265-40624

HA19 - 42333-42578-42259-40625

HA20 - 42075-42577-42291-40616

HA21 - 42276-42576-42055-40612

HA22 - 42019-42571-42275-40608

HA31 - 41126-42261-42344-44030

HA32 - 46010-42069-42118-44023

HA33 - 41140-42289-42287-44037

Spare 42209

 

GWR Castle sets

GW02 - 48106-48105-48104-49102

GW05 - 48113-48114-48115-49105

GW06 - 48116-48117-48118-49106

GW07 - 48121-48120-48119-49107

GW08 - 48124-48129-48122-49108

GW93 - 48106-48126-481079-(temporary formation as of 26/01)

 

HTH,

Dave

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34 minutes ago, pete_mcfarlane said:

Out of interest, do the short formations have any limitations on their maximum speed due to the reduced brake force available?

 

They should have - waits for Stationmaster Mike and/or David Hill to add their knowledge

The NMT is certainly limited when it runs as 2+4 on rare outings instead of the usual 2+5.

 

The shortest *scheduled* [*] operations with HSTs were probably the 2+2s used on Virgin XC operated Manchester Airport-Edinburgh services when the 158 provided by North Western wasn't available.

Mini HST vice CL158

 

[*] I believe it only happened on a handful of times

Edited by newbryford
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5 hours ago, Gwiwer said:

Still settling down and possibly changed daily.  I haven't noticed a slam-door rake in use recently though so they might have finished.  

 

The shortest passenger-carrying HST formation of all-time was the single power car which made it to Par after detaching from a failed (derailed?) set on the Newquay branch.  The passengers were conveyed in the former guard's van.

I believe the GW slam door 2+4 sets did indeed finish on 31/12/2019.

 

cheers

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15 hours ago, JohnR said:

Does anyone have a handy list of the formations of the various short HST sets operated by the likes of GWR etc?

 

The shortest sets that can be used for 125mph running is 2+ 5 trailers, however such formations have only been employed by open access operators like of Grand Central

 

The newly formed GWR and ScotRail sets are smaller still BUT are limited to 100mph as there are not enough trailers to provide the brake force necessary to stop from 125mph.

 

 

 

 

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6 hours ago, pete_mcfarlane said:

Out of interest, do the short formations have any limitations on their maximum speed due to the reduced brake force available?

We have been here many time before.

Since the power car brakes were changed in the 80's from the original two stage brake using Girling brake discs to the single stage brake using (originally) BSI or latterly Knorr discs, the braking capability of the HST power cars has complied with the braking curve over the whole speed range up to 125mph.  (Unless there has been a further change in recent years, which I doubt). As the DM&EE engineer managing the change, I was involved in the tests of back to back power cars on the GW main line that proved the calculations and lab tests to be true. Note that nominally 80% of the brake force is set through the brake discs and 20% through the tread brake. The tread brake is provided to keep the treads conditioned and aid adhesion.

Getting the WR operations team to agree to the test was difficult: they argued that light locomotives had a speed limit lower than line speed. This being driven by the fact that the braking capability of locos varied from barely adequate to barely noticeable. However, it was pointed out that the HST power car was just that: not a loco, so the tests went ahead. The acceleration of a pair of power cars with an enthusiastic footplate crew curious to see what they would do was impressive. 

With the original set up the brake force was reduced at high speeds (I think 90mph was the changeover - KenW will remember) and increased below that speed so that a full service brake to rest from 125mph would be done at an average retardation of 0.9m/s/s. At lower initial speeds the average deceleration would be higher (until initial speed was low enough for brake force build up time to be more significant).

With the revised set up the average retardation was constant independent of the initial speed and independent of the number of trailer cars.

So the only reason for limiting the maximum speed of the short formation will be to give an extra braking distance contingency. This would be eminently sensible as the effect of Wheel Slip Protection activity on even a single axle will be more pronounced on a shorter train as the percentage loss of brake force will be greater. There is nominally 300m contingency on level track for 125mph signalling and full service braking. It isn't excessive for a full formation set.

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6 hours ago, newbryford said:

 

They should have - waits for Stationmaster Mike and/or David Hill to add their knowledge

The NMT is certainly limited when it runs as 2+4 on rare outings instead of the usual 2+5.

 

The shortest *scheduled* [*] operations with HSTs were probably the 2+2s used on Virgin XC operated Manchester Airport-Edinburgh services when the 158 provided by North Western wasn't available.

Mini HST vice CL158

 

[*] I believe it only happened on a handful of times

 

IIRC they also operated Manchester Airport to Bolton.

 

FGW operated scheduled 2+2 HSTs and on one occasion a 2+1 on the Cotswold Line as DMU replacements. This was during engineering work and they operated an hourly Hanborough to Worcester SH shuttle.

 

43042 tnt 43182 15 6 08 2

 

The shortest ever unscheduled passenger carrying HST was the famous 1+0 after the Luxulyan derailment in 1991.

 

Cheers

David

 

 

 

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9 hours ago, Davexoc said:

Taking info from the last 8 months Rail Express, alot from the derogations list as they are still slam-door and so non compliant.

 

Scotrail sets

HA01 - 41124-42256-42255-44029

HA02 - 41144-42032-42295-44039

HA03 - 41104-42208-42206-44066

HA04 - 41130-42325-42267-44032 (disbanded as of 26/01)

HA05 - 41022-42010-42030-44010

HA06 - 41158-42129-42200-44086

HA17 - 40610-42360-42551-42252

HA18 - 42293-42553-42265-40624

HA19 - 42333-42578-42259-40625

HA20 - 42075-42577-42291-40616

HA21 - 42276-42576-42055-40612

HA22 - 42019-42571-42275-40608

HA31 - 41126-42261-42344-44030

HA32 - 46010-42069-42118-44023

HA33 - 41140-42289-42287-44037

Spare 42209

 

GWR Castle sets

GW02 - 48106-48105-48104-49102

GW05 - 48113-48114-48115-49105

GW06 - 48116-48117-48118-49106

GW07 - 48121-48120-48119-49107

GW08 - 48124-48129-48122-49108

GW93 - 48106-48126-481079-(temporary formation as of 26/01)

 

HTH,

Dave

 

Thanks, thats exactly what I was looking for. Now to match up with the R numbers from the catalogue. 

 

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7 hours ago, phil-b259 said:

 

The shortest sets that can be used for 125mph running is 2+ 5 trailers, however such formations have only been employed by open access operators like of Grand Central

 

The newly formed GWR and ScotRail sets are smaller still BUT are limited to 100mph as there are not enough trailers to provide the brake force necessary to stop from 125mph.

 

 

 

 

 

Speaking to a driver, there is no limit to the speed of the ScotRail sets, albeit there arnt any stretches of line with speeds above 100mph north of the central belt in any case. 

 

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For information, here is the GW formations for today

 

GW07
43154 48121 48120 48119 49107 43093
5C02 06.15 Laira to Plymouth
2C02 06.41 Plymouth to Truro
2P05 08.30 Truro to Plymouth
2C19 10.17 Plymouth to Truro
2P12 11.54 Truro to Plymouth
2C27 14.17 Plymouth to Truro
2P20 15.54 Truro to Plymouth
2E22 17.51 Plymouth to Exeter S.D
2M73 21.51 Exeter S.D to Bristol TM
5M73 00.18 Bristol TM to St Philips Marsh

GW02
43098 48106 48105 48104 49102 43155
5C05 05.02 St Philips Marsh to Bristol TM
2C05 05.24 Bristol TM to Plymouth
2U12 08.47 Plymouth to Cardiff
2C77 13.00 Cardiff to Plymouth
2U32 18.45 Plymouth to Cardiff
5U32 22.24 Cardiff to St Philips Marsh

GW05
43153 48115 48114 48113 49105 43094
5C07 06.14 St Philips Marsh to Bristol TM
2C07 06.44 Bristol TM to Plymouth
5C07 09.36 Plymouth to Laira
5Z28 20.48 Laira to Plymouth
2E28 21.32 Plymouth to Exeter S.D
5E28 22.56 Exeter S.D to Exeter New Yard

GW08
43198 48124 48129 48122 49108 43042
5U02 04.31 Exeter New Yard to Taunton
2U02 05.15 Taunton to Cardiff
2C67 08.00 Cardiff to Plymouth
2U20 12.49 Plymouth to Cardiff
2C85 17.00 Cardiff to Taunton
2U30 19.07 Taunton to Cardiff
2C95 22.00 Cardiff to Bristol TM
5C95 23.13 Bristol TM to St Philips Marsh

GW04
43186 48112 48111 48110 49104 43040
5C65 05.38 St Philips Marsh to Gloucester
2C65 07.00 Gloucester to Taunton
2U10 09.18 Taunton to Cardiff
2C75 12.00 Cardiff to Taunton
2U22 15.15 Taunton to Cardiff
2C87 18.00 Cardiff to Plymouth
5C87 22.45 Plymouth to Laira

GW09
43094 48127 48135 48125 49109 43192
5C06 08.00 Laira to Plymouth
2C06 08.47 Plymouth to Truro
2P09 10.29 Truro to Plymouth
2C23 12.19 Plymouth to Truro
2P16 13.54 Truro to Plymouth
5P16 15.22 Plymouth to Laira

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14 hours ago, david.hill64 said:

We have been here many time before.

Since the power car brakes were changed in the 80's from the original two stage brake using Girling brake discs to the single stage brake using (originally) BSI or latterly Knorr discs, the braking capability of the HST power cars has complied with the braking curve over the whole speed range up to 125mph.  (Unless there has been a further change in recent years, which I doubt). As the DM&EE engineer managing the change, I was involved in the tests of back to back power cars on the GW main line that proved the calculations and lab tests to be true. Note that nominally 80% of the brake force is set through the brake discs and 20% through the tread brake. The tread brake is provided to keep the treads conditioned and aid adhesion.

Getting the WR operations team to agree to the test was difficult: they argued that light locomotives had a speed limit lower than line speed. This being driven by the fact that the braking capability of locos varied from barely adequate to barely noticeable. However, it was pointed out that the HST power car was just that: not a loco, so the tests went ahead. The acceleration of a pair of power cars with an enthusiastic footplate crew curious to see what they would do was impressive. 

With the original set up the brake force was reduced at high speeds (I think 90mph was the changeover - KenW will remember) and increased below that speed so that a full service brake to rest from 125mph would be done at an average retardation of 0.9m/s/s. At lower initial speeds the average deceleration would be higher (until initial speed was low enough for brake force build up time to be more significant).

With the revised set up the average retardation was constant independent of the initial speed and independent of the number of trailer cars.

So the only reason for limiting the maximum speed of the short formation will be to give an extra braking distance contingency. This would be eminently sensible as the effect of Wheel Slip Protection activity on even a single axle will be more pronounced on a shorter train as the percentage loss of brake force will be greater. There is nominally 300m contingency on level track for 125mph signalling and full service braking. It isn't excessive for a full formation set.

Your doubts regarding a further change were wrong- they did get changed again! The Great Western power cars were further modified so that the brake force was reduced- basically the bogie brakes on the power car went to approx. 3.5 bar maximum no matter how high a brake step was applied. Prior to that (and very contrary to instructions!!) the power car brakes were good enough to stop from 125 without any coaches in the opinion of many drivers.

 

More recently a trial was carried out on EMR so it's been proved that 2+4 is OK for 125mph operation, but if I were the driver on that I'd not "dick about" if encountering a cautionary aspect as even a six car can prove harder to kill the speed on than an eight car...

 

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1 hour ago, fiftyfour fiftyfour said:

More recently a trial was carried out on EMR so it's been proved that 2+4 is OK for 125mph operation, but if I were the driver on that I'd not "dick about" if encountering a cautionary aspect as even a six car can prove harder to kill the speed on than an eight car...

There are few stretches of line over which the short-form sets operate where the maximum permitted speed is greater than 100mph.  On the GWR route only some of the Bristol - Exeter route is 125mph IIRC.  Nowhere west of Exeter is greater than 100mph and most of it no more than 75mph.  

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21 minutes ago, Gwiwer said:

There are few stretches of line over which the short-form sets operate where the maximum permitted speed is greater than 100mph.  On the GWR route only some of the Bristol - Exeter route is 125mph IIRC.  Nowhere west of Exeter is greater than 100mph and most of it no more than 75mph.  

Where is 125mph allowed Bristol to Exeter? They may have upped the speed but it was 110mph from Uphill to Huntspill back in the day and no more than 100mph anywhere else.

 

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3 hours ago, fiftyfour fiftyfour said:

Your doubts regarding a further change were wrong- they did get changed again! The Great Western power cars were further modified so that the brake force was reduced- basically the bogie brakes on the power car went to approx. 3.5 bar maximum no matter how high a brake step was applied. Prior to that (and very contrary to instructions!!) the power car brakes were good enough to stop from 125 without any coaches in the opinion of many drivers.

 

 

Thanks for the update: just shows how important it is not to rely on old information.

 

Do you know why the change was made? Degrading the performance of something is not done lightly.

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The change was made to reduce brake disc wear on the power cars, I gather the higher proportion of stopping/starting on GW sets made it worthwhile and it was always on the proviso that the braking performance would be unaffected in normal operation as the coaches maintained the required stopping distances. From experience when we had a mix of (then) Virgin XC sets and GW sets the Virgin ones were sharper at stopping even with one less coach, but I have absolutely no scientific or other evidence to back that up and it could have been perception drawn from observing gauges!

 

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