GWR Class 769 information & discussion.

DownFast

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I wouldn't be in too much of a rush to get them introduced - they're older than the 165s they're replacing, and evidence from Northern and TfW doesn't bode well for their reliability.
Environmentally the benefits aren't that great - they're likely to turn the diesels off only between Reading and Wokingham, and between Reigate and Redhill or Gatwick. (Ash to Guildford is possible but uncertain afaik).
Guildford to Ash (or Shalford Jct to Ash for services towards Reading) is on DC power.

Does anyone know what makes Twyford-Henley preferable to Slough-Windsor ? Seems a bit arbitrary.
It's to do with the 3 minute turnaround at Windsor and the fact that changing ends on a 4-car can't be done within the same timing allowance as for 2 or 3 cars. So it would either need the timetable to be re-written (possible in future I guess as the Windsors are 'locked in') or for trains to be double manned with a driver at each end. Plus, as has been mentioned up-thread, some of the Windsors are worked by Padd drivers, and the intention is to train Reading drivers initially. Not that that means Padd drivers won't be trained on 769s eventually.
 
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DelW

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Guildford to Ash (or Shalford Jct to Ash for services towards Reading) is on DC power.
Is that definite now? It was extensively discussed a while ago (probably somewhere much earlier in this thread), and doubt was cast whether DC would be used on this section, especially by services that don't stop at Ash.
 

DownFast

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Is that definite now? It was extensively discussed a while ago (probably somewhere much earlier in this thread), and doubt was cast whether DC would be used on this section, especially by services that don't stop at Ash.
Yes, definitely definite. The mileage accumulation runs are changing from diesel to DC when back on the 3rd rail beyond Aldershot Sth Jct, and from DC to diesel between Ash and Aldershot Sth Jct. The traction changeover signage is due to be installed any time now.
 

DelW

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Yes, definitely definite. The mileage accumulation runs are changing from diesel to DC when back on the 3rd rail beyond Aldershot Sth Jct, and from DC to diesel between Ash and Aldershot Sth Jct. The traction changeover signage is due to be installed any time now.
Thanks, that's good news, since that should eliminate regular diesel traction from Guildford station (other than the 2tpd XC, if they ever return, and XC weekend diversions).
 

swt_passenger

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It’s already been stated they will use third rail between Aldershot South Jn and Guildford in the eastbound direction, and between Shalford Jn and Aldershot South Jn westbound. It was all explained in detail in this thread a few months ago, after I quoted Modern Railways in post #928 things were clarified over a few further posts.

The main thing is that earlier in the thread it had been wrongly assumed that they could only changeover when stopped.
 
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DelW

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It’s already been stated they will use third rail between Aldershot South Jn and Guildford in the eastbound direction, and between Shalford Jn and Aldershot South Jn westbound. It was all explained in detail in this thread a few months ago, after I quoted Modern Railways in post #928 things were clarified over a few further posts.

The main thing is that earlier in the thread it had been wrongly assumed that they could only changeover when stopped.
My apologies, I'd remembered the long discussion but I'd forgotten that it had finally been resolved. (Posting on a tablet it's not very easy to go back through long threads.)
 

swt_passenger

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My apologies, I'd remembered the long discussion but I'd forgotten that it had finally been resolved. (Posting on a tablet it's not very easy to go back through long threads.)
No problem. The main reason I remembered the ‘change’ was that Modern Railways had reported something quite different to what had previously been accepted as the likely way of operating.
 

Meerkat

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Thanks, that's good news, since that should eliminate regular diesel traction from Guildford station (other than the 2tpd XC, if they ever return, and XC weekend diversions).
Unfortunately not - the eastbound 769's will be starting their diesels in Guildford station
 

JonathanH

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Bessie

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Passing Reading today with the red 387/2’s all departed there seems to be more 769’s stabled at the depot
 

MatthewRead

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They don't need to be - there is no operational need for them to go there.

Previous postings have indicated that they won't be cleared beyond Maidenhead for GWR use. One has reached Slough in the past during the phase when Colas were doing test runs.

https://www.railforums.co.uk/thread...mation-discussion.174866/page-25#post-5107758
But one of the earlier posts says Paddington based drivers will be trained on them despite them not being intended for the GWML I guess to deputize for a 387.
 

JonathanH

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But one of the earlier posts says Paddington based drivers will be trained on them despite them not being intended for the GWML I guess to deputize for a 387.
No, it doesn't. They can't deputise for a 387 because they don't have anything like the same performance.

Messages by informed posters say that Paddington drivers won't initially be trained, if at all, and that there are four links of Reading drivers to train first.

From this very page:
Plus, as has been mentioned up-thread, some of the Windsors are worked by Padd drivers, and the intention is to train Reading drivers initially. Not that that means Padd drivers won't be trained on 769s eventually.
Even if Paddington drivers are trained it would be so that they can operate them on the proposed routes.
 
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MatthewRead

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No, it doesn't. They can't deputise for a 387 because they don't have anything like the same performance.

Messages by informed posters say that Paddington drivers won't initially be trained and that there are four links of Reading drivers to train first.
Yes I knew that their inferior acceleration makes then unsuitable but if there were another chronic shortage of IET's they could be used on Paddington-Oxfords or even to Bedwyn reinstating direct services.
 

JonathanH

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Yes I knew that their inferior acceleration makes then unsuitable but if there were another chronic shortage of IET's they could be used on Paddington-Oxfords or even to Bedwyn reinstating direct services.
Let's hope there isn't another chronic shortage of IETs. It seems the problem is under control at the moment.

I imagine that GWR will concentrate on getting them working on the intended routes with the intended traincrew before trying to get them used on other routes.
 

JN114

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Why? Why not start the diesels as soon as you approach Shalford Junction? Sorry if I missed anything here.

Essentially, the sum of all the risk factors was too great:-

Unable to provide changeover signage at correct point within tunnel, approaching a significant speed reduction for the junction so focus needs to be there not heads down turning on engines etc, recovery from a tunnel if changeover fails, and more.

Individually each would probably be ok, and is how for example Aldershot South is fine for Dynamic while Shalford isn’t.
 

Nicholas Lewis

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Surely Ash to Guildford is too short to be worth the effort?
Ash Jcn to Shalford Jcn is around 13km vs 11km from Reading to Wokingham so definitely worthwhile but only practical if they can change over on the move which I believe they can but whether thats the preferred method of operation isn't clear.

I fear we will never find out though....
 

DownFast

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Ash Jcn to Shalford Jcn is around 13km vs 11km from Reading to Wokingham so definitely worthwhile but only practical if they can change over on the move which I believe they can but whether thats the preferred method of operation isn't clear.

I fear we will never find out though....
Yes, they can change power mode to/from DC and diesel on the move (although not currently to AC - but that's not something that's really relevant at present). But each location has been risk-assessed for dynamic power changeover and whether there are potential risks from e.g. distraction at the specific location and for the type of changeover.

Changing to to DC is a very simple process: press the DC system select button and you're good to go, it takes a couple of seconds. But changing to diesel is more complicated and involves pressing and holding the diesel system select button while observing all sorts of indications in the cab. The whole process takes about 30 seconds, so is not ideal if the driver's attention needs to be focussed elsewhere (e.g. signals protecting level crossings).

Plus at locations where all GWR services stop anyway (Wokingham, Reigate etc.) there's no point in carrying out a dynamic changeover so it's all static.

I imagine that GWR will concentrate on getting them working on the intended routes with the intended traincrew before trying to get them used on other routes.
That's it in a nutshell. If the initial introduction is successful, then I can see 769s being used on other services which may involve training other depots. Pretty much every other traction introduction on GWR has ended up being like that (387s to Cardiff, Par drivers being trained on 80x etc.)
 
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swt_passenger

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Ash Jcn to Shalford Jcn is around 13km vs 11km from Reading to Wokingham so definitely worthwhile but only practical if they can change over on the move which I believe they can but whether thats the preferred method of operation isn't clear.

I fear we will never find out though....
They can change over on the move from generator to/from third rail. But not between AC & DC. It’s been confirmed numerous times in this thread since the discussion around post #928 that I mentioned a few of days ago.
 

Nicholas Lewis

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Yes, they can change power mode to/from DC and diesel on the move (although not currently to AC - but that's not something that's really relevant at present). But each location has been risk-assessed for dynamic power changeover and whether there are potential risks from e.g. distraction at the specific location and for the type of changeover.

Changing to to DC is a very simple process: press the DC system select button and you're good to go, it takes a couple of seconds. But changing to diesel is more complicated and involves pressing and holding the diesel system select button while observing all sorts of indications in the cab. The whole process takes about 30 seconds, so is not ideal if the driver's attention needs to be focussed elsewhere (e.g. signals protecting level crossings).

Plus at locations where all GWR services stop anyway (Wokingham, Reigate etc.) there's no point in carrying out a dynamic changeover so it's all static.


That's it in a nutshell. If the initial introduction is successful, then I can see 769s being used on other services which may involve training other depots. Pretty much every other traction introduction on GWR has ended up being like that (387s to Cardiff, Par drivers being trained on 80x etc.)
Thanks for that update and that is great to hear but given what you say about diesel start procedure it seems highly probably that it will be diesel from Guildford when going south and westbound to avoid the issue of driver distraction.
 

JN114

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Thanks for that update and that is great to hear but given what you say about diesel start procedure it seems highly probably that it will be diesel from Guildford when going south and westbound to avoid the issue of driver distraction.

Dynamic Changeover at Shalford Junction towards Guildford

Static Changeover at Guildford Station towards Redhill
 

DownFast

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Thanks for that update and that is great to hear but given what you say about diesel start procedure it seems highly probably that it will be diesel from Guildford when going south and westbound to avoid the issue of driver distraction.
Not highly probable, it's definite, and is already happening, as in JN114's post.
 

HamworthyGoods

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Guildford to Ash (or Shalford Jct to Ash for services towards Reading) is on DC power.


It's to do with the 3 minute turnaround at Windsor and the fact that changing ends on a 4-car can't be done within the same timing allowance as for 2 or 3 cars. So it would either need the timetable to be re-written (possible in future I guess as the Windsors are 'locked in') or for trains to be double manned with a driver at each end. Plus, as has been mentioned up-thread, some of the Windsors are worked by Padd drivers, and the intention is to train Reading drivers initially. Not that that means Padd drivers won't be trained on 769s eventually.

That’s not the case, journey time is 6 minutes each way and change ends for a 769 is 4 minutes so that works fine. Like at the Saturday timetable on the branch in Real Time trains.
 

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