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Newquay HST exemption.

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8001F

Posts: 4058
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Newquay HST exemption. - Posted: July 2, 2020 - 4:38 PM Quote and reply
Class 253/254 HSTs formed of 4 coaches or less are permitted to operate between Par and Newquay on one engine only. This supersedes the Sectional Appendix instructions for this class of train.
This does not apply during times of low adhesion, when the existing Sectional Appendix instructions for Class 253/25 4 HSTs
remain in force.
NR 02.07.20

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Sean Emmett

Posts: 200
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Re: Newquay HST exemption. - Posted: July 2, 2020 - 8:44 PM Quote and reply
8001F said:
Class 253/254 HSTs formed of 4 coaches or less are permitted to operate between Par and Newquay on one engine only. This supersedes the Sectional Appendix instructions for this class of train.
This does not apply during times of low adhesion, when the existing Sectional Appendix instructions for Class 253/25 4 HSTs
remain in force.
NR 02.07.20

A bit cryptic?
Does this mean that nornal 2+7 or 2+8 (or even 2+9) were ok, but mini hsts have a problem (overpowered?).
A layman's explanation would be helpful!



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8001F

Posts: 4058
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Re: Newquay HST exemption. - Posted: July 2, 2020 - 9:29 PM Quote and reply
Sean Emmett said:
8001F said:
Class 253/254 HSTs formed of 4 coaches or less are permitted to operate between Par and Newquay on one engine only. This supersedes the Sectional Appendix instructions for this class of train.
This does not apply during times of low adhesion, when the existing Sectional Appendix instructions for Class 253/25 4 HSTs
remain in force.
NR 02.07.20

A bit cryptic?
Does this mean that nornal 2+7 or 2+8 (or even 2+9) were ok, but mini hsts have a problem (overpowered?).
A layman's explanation would be helpful!


I presumed that there is an instruction that short HSTs must operate with 2 power cars west of Exeter and this has been relaxed for the Newquay branch apart from damp or wet rail conditions on Luxulyan Bank where extra traction is required. I've had to give up on a search for the relevant part of the Sectional Appendix but I'm sure if one power car fails the other can cope unassisted on the branch. Longer formations may not make it with one!
IU



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8001F

Posts: 4058
Location:
Re: Newquay HST exemption. - Posted: July 2, 2020 - 11:05 PM Quote and reply
8001F said:
Sean Emmett said:
8001F said:
Class 253/254 HSTs formed of 4 coaches or less are permitted to operate between Par and Newquay on one engine only. This supersedes the Sectional Appendix instructions for this class of train.
This does not apply during times of low adhesion, when the existing Sectional Appendix instructions for Class 253/25 4 HSTs
remain in force.
NR 02.07.20

A bit cryptic?
Does this mean that nornal 2+7 or 2+8 (or even 2+9) were ok, but mini hsts have a problem (overpowered?).
A layman's explanation would be helpful!


I presumed that there is an instruction that short HSTs must operate with 2 power cars west of Exeter and this has been relaxed for the Newquay branch apart from damp or wet rail conditions on Luxulyan Bank where extra traction is required. I've had to give up on a search for the relevant part of the Sectional Appendix but I'm sure if one power car fails the other can cope unassisted on the branch. Longer formations may not make it with one!
IU


A further surf during Match of the Day waffling produced the following: the bits bracketed are a new entry which maybe should have had Par and Newquay inserted?
{Short Formed HSTs operating OEO
Class 253/254 HSTs formed of 4 coaches or less are permitted to operate between (insert location) and (insert
location) on one engine only. This supersedes the Sectional Appendix instructions for this class of train.
This does not apply during times of low adhesion, when the existing Sectional Appendix instructions for Class
253/25 4 HSTs remain in force.}

CLASS 253/254 (HST) - WORKING ON ONE
ENGINE ONLY
The following supplement train operating company working instructions when a train is to proceed with only one
power car available for traction :
1. Lines over which assistance must always be provided

Exeter St David’s to Exeter Central Up direction only.

Par and Newquay: Assistance must be provided on the front in the down direction.
In the up direction the assisting locomotive should not normally apply power and MUST NOT apply power when approaching AOCL level crossings.

Swansea Loop West Jn to Cockett Tunnel Down direction only.

CLASS 220/221 TRAINS WORKING ON
REDUCED TRACTION POWER
1. Four-car units with at least two engines, and five-car units with at least three engines available for traction may operate on Western Route without restriction. Trains consisting of more than one unit must have the equivalent ratio of engines available throughout the train.
NR 02.07.20



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heatonj

Posts: 39
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Re: Newquay HST exemption. - Posted: July 3, 2020 - 4:29 PM Quote and reply
8001F said:
8001F said:
Sean Emmett said:
8001F said:
Class 253/254 HSTs formed of 4 coaches or less are permitted to operate between Par and Newquay on one engine only. This supersedes the Sectional Appendix instructions for this class of train.
This does not apply during times of low adhesion, when the existing Sectional Appendix instructions for Class 253/25 4 HSTs
remain in force.
NR 02.07.20


Does this mean that nornal 2+7 or 2+8 (or even 2+9) were ok, but mini hsts have a problem (overpowered?).
A layman's explanation would be helpful!


I presumed that there is an instruction that short HSTs must operate with 2 power cars west of Exeter and this has been relaxed for the Newquay branch apart from damp or wet rail conditions on Luxulyan Bank where extra traction is required. I've had to give up on a search for the relevant part of the Sectional Appendix but I'm sure if one power car fails the other can cope unassisted on the branch. Longer formations may not make it with one!
IU


A further surf during Match of the Day waffling produced the following: the bits bracketed are a new entry which maybe should have had Par and Newquay inserted?
{Short Formed HSTs operating OEO
Class 253/254 HSTs formed of 4 coaches or less are permitted to operate between (insert location) and (insert
location) on one engine only. This supersedes the Sectional Appendix instructions for this class of train.
This does not apply during times of low adhesion, when the existing Sectional Appendix instructions for Class
253/25 4 HSTs remain in force.}

CLASS 253/254 (HST) - WORKING ON ONE
ENGINE ONLY
The following supplement train operating company working instructions when a train is to proceed with only one
power car available for traction :
1. Lines over which assistance must always be provided

Exeter St David’s to Exeter Central Up direction only.

Par and Newquay: Assistance must be provided on the front in the down direction.
In the up direction the assisting locomotive should not normally apply power and MUST NOT apply power when approaching AOCL level crossings.

Swansea Loop West Jn to Cockett Tunnel Down direction only.

CLASS 220/221 TRAINS WORKING ON
REDUCED TRACTION POWER
1. Four-car units with at least two engines, and five-car units with at least three engines available for traction may operate on Western Route without restriction. Trains consisting of more than one unit must have the equivalent ratio of engines available throughout the train.
NR 02.07.20


I think it means one power car 2+4 used to need assistance but are now exempted and can run unassisted except in low adhesion conditions when assisatance is then required. It did read as if overpowered with 2 p c when separated from its context.
JH


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dstannard

Posts: 27
Location: cheshire, uk
Newquay HST exemption - Posted: July 4, 2020 - 10:46 AM Quote and reply
I make it that the expected balancing speed of a 2+4 HST with an engine out is around 38 mph on the 1:40 gradient of Luxulyan bank, so would have thought that is ok without assistance in conditions of normal adhesion.

David Stannard
RPS Committee - Technical
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