Trains fitted with multiple train protection systems

[saltywalrus]

Hi all,

I've been trying to wrap my head around the mess of train protection systems on the GWML. Paddington - Airport Junction is fitted with TPWS, ATP, and ETCS L2. As far as I can tell, the GWR 80xs are fitted with both TPWS and ATP and the 345s TPWS and ETCS. Since TPWS' only function is to provide intervention braking, which both ATP and ETCS are capable of doing on their own, does it still remain active alongside ATP/TPWS? If so, does that mean that a SPAD/overspeed will trip both systems and require them to be reset seperately?

Thanks

 

[800301]

Hi all,

I've been trying to wrap my head around the mess of train protection systems on the GWML. Paddington - Airport Junction is fitted with TPWS, ATP, and ETCS L2. As far as I can tell, the GWR 80xs are fitted with both TPWS and ATP and the 345s TPWS and ETCS. Since TPWS' only function is to provide intervention braking, which both ATP and ETCS are capable of doing on their own, does it still remain active alongside ATP/TPWS? If so, does that mean that a SPAD/overspeed will trip both systems and require them to be reset seperately?

Thanks

If you are running in ETCS L2 then TPWS has no effect on the train

If you are running on ATP, TPWS will still intervene and in most places you’ll be tripped by TPWS before ATP starts getting upset.

If you are unlucky enough to have a SPAD with an ATP train, yes you will have to reset both systems separately along with a lot of explaining

 

[NSEWonderer]

Just coming out of the Royal oak portal on the down alongside Westbourne park is the CBTC switchover to TPWS. First year or so of full cos running an unusual SPAD occured I believe where driver got a proceed main aspect on the signal protecting the mainline from the crossrail side but did not realise they hadn't movement authority past the block marker board before the signal which is the last area of CBTC. As a result the brakes came on and if I remember correctly it was recorded as a SPAD.

Its an odd setup but drivers have to ensure during transition to manual control there that MA is showing past the block marker board and that the main aspect signal is a proceed aspect.

 

[saltywalrus]

If you are running in ETCS L2 then TPWS has no effect on the train

If you are running on ATP, TPWS will still intervene and in most places you’ll be tripped by TPWS before ATP starts getting upset.

If you are unlucky enough to have a SPAD with an ATP train, yes you will have to reset both systems separately along with a lot of explaining

Thanks, that's exactly what I was looking for!

Just coming out of the Royal oak portal on the down alongside Westbourne park is the CBTC switchover to TPWS. First year or so of full cos running an unusual SPAD occured I believe where driver got a proceed main aspect on the signal protecting the mainline from the crossrail side but did not realise they hadn't movement authority past the block marker board before the signal which is the last area of CBTC. As a result the brakes came on and if I remember correctly it was recorded as a SPAD.

Its an odd setup but drivers have to ensure during transition to manual control there that MA is showing past the block marker board and that the main aspect signal is a proceed aspect.

Do 345s running to Reading transition directly to TPWS at Royal Oak? Is there an infrastructure reason why they can't run on ETCS until Airport Junction, or is it just so they only have to switch systems once rather than twice?

 

[800301]

Thanks, that's exactly what I was looking for!


Do 345s running to Reading transition directly to TPWS at Royal Oak? Is there an infrastructure reason why they can't run on ETCS until Airport Junction, or is it just so they only have to switch systems once rather than twice?

The 345’s are on CBTC until the exit signal at the end of the portal, if you’re on a GWR train and look over, you’ll see them sometimes approaching that signal which can be showing danger until the last few seconds much faster than you’d ever be able to approach if you were running in AWS/TPWS. The reason they don’t change over to ETCS from the exit is that whole area will be redesigned for Old Oak Common, when OOC opens there should be ETCS from Paddington Mainline all the way to Heathrow, the 80x will still likely run on ATP as there is no way to dynamically changeover on the move with ATP

 

[zwk500]

I've been trying to wrap my head around the mess of train protection systems on the GWML. Paddington - Airport Junction is fitted with TPWS, ATP, and ETCS L2.

Do 345s running to Reading transition directly to TPWS at Royal Oak? Is there an infrastructure reason why they can't run on ETCS until Airport Junction, or is it just so they only have to switch systems once rather than twice?

The ETCS L2 overlay starts around Ealing Broadway not Paddington. This gap was left to allow for the Old Oak Common works (as mentioned by 800301).

A Class 345 from the Crossrail core to Reading will transtion:
from CBTC to TWPS/AWS at Royal Oak,
from TPWS/AWS to ETCS L2 at Ealing Broadway,
from ETCS L2 to TWPS/AWS at Stockley Bridge Jn.

Both Heathrow Branches are fitted with ETCS L2 so a Class 345 to the airport, and the Class 387s for the Heathrow Express, do not transition out of ETCS at Airport Junction.

the 80x will still likely run on ATP as there is no way to dynamically changeover on the move with ATP

Is there a timescale for ETCS L2 fitment out to Reading, where they could change from ATP to ETCS during the station stop?

 

[saltywalrus]

Thanks. Do you know if ATP / ETCS are fitted on both the fast and slow lines?

 

[zwk500]

Thanks. Do you know if ATP / ETCS are fitted on both the fast and slow lines?

Both systems are fitted to all 4 lines (Mains and Reliefs on the GWML, not Fast/Slows, pedantically) from Paddington to Airport Jn. ATP is fitted from on the main lines only from Airport Jn to Bristol (Parkway via Hullavington, Temple Meads via Bath) but not the Filton Bank.

(Edited due to correction in post #9)

 

[800301]

Both systems are fitted to all 4 lines (Mains and Reliefs on the GWML, not Fast/Slows, pedantically). ATP is fitted from Paddington to Bristol (Parkway via Hullavington, Temple Meads via Bath) but not the Filton Bank or Berks & Hants route.

ATP isn’t fitted on relief lines except between Paddington and Airport junction, it’s fitted in sections along the B and H

 

[zwk500]

ATP isn’t fitted on relief lines except between Paddington and Airport junction, it’s fitted in sections along the B and H

So it is, that'll teach me to rely on ORM and a quick glance at the top of the Appendix!

 

[alxndr]

ATP isn’t fitted on relief lines except between Paddington and Airport junction, it’s fitted in sections along the B and H

Only on the B&H as far as Newbury from what I recall