Chiltern 172s and related Evergreen 3 enhancements

[whole diary]

[paul7575]

Rail is often misleading, but not as often as Mordern Railways.....sometimes I get the impression that rail industry journos often know not of what they speak, and just (mis-)interpret press releases.....rather than talk to those on the ground.

Problem is this particular article in Rail (Issue 643 page 50) wasn't just slightly wrong.
Regarding 'remodelling Aynho Junction' it actually reads:

'Here the 50mph flyover will be replaced with a flat junction in the down direction...'

How they get to that, given the stuff in the track access application, and on the Evergreen 3 site, I'm not sure...

Paul

[IndustryInsider]

To build out Bicester North up platform

The early work has started there, with lineside equipment moved, and diggers creating a shallow trench where the new Up line will go.  Lengths of track have been dropped ready to lay it shortly.  Bicester North could have been made into a proper passing point for southbound trains of course, had this track been laid and the old Up platform line left in situ for trains that are stopping at Bicester North.  That plan would not have incurred the extra cost of rebuilding the platform, footbridge and lifts. I'm sure there's a reason why they chose to rebuild the platform, but on the face of it, it seems a little strange.

[Btline]

I am surprised they are not installing more passing points. Yes - they wouldn't be used in normal service, but next time a tree falls on the tracks near Harrow, screwing up the whole service, being able to hold a stopper at Beconsfield for 15 mins to let some expresses through would be useful!

[eightf48544]

Interesting comment about passing points, when you think that when the GC^» (Great Central Railway - link to heritage line)/GW^▸ (Great Western) joint was built with its GC links to Marylebone and Grendon Underwood Junction  and and GW links to OO^▸ ((Double O) - model railway, 4mm to 1 foot scale) and Aynho. there were around 11 passing places  from OO to Aynho.

Another example of how much capacity has been taken out of the railway, without closing the line. 

[IndustryInsider]

An end to the confusion?  The latest RAIL magazine talks of a new 'Down' line being provided next to the 'Up' line at Aynho Junction with a speed of 90mph, but it states that the current down line over the flyover with its 40mph limit will remain.  So, assuming that's right, there'll be an additional overtaking place as slow trains can be put into this flyover 'loop' if necessary whilst a fast train speeds past on the new 'Up' line, and also if a fast train would otherwise conflict with a train on the 'Up' line heading towards Oxford it could also be routed via the loop with minimal delay and no conflicts - similar to the revised layout at Northolt Junction. 

Seems quite a neat solution and proves our suspicions that the track curvature after the flyover would prevent the increase in speeds quoted!

[paul7575]

Sounds more like Rail gradually back pedalling to me I'm afraid. 

I can't see any advantage to introducing a fast flat junction and leaving the flyover at 40 mph, given the traffic levels on the Banbury - Oxford route.

Do Rail make any attempt to explain why they are reporting something completely different to the detail published in the track access application?

Paul

[SandTEngineer]

The Signalling Scheme Sketch I have seen has the Aynho Junction Up Line turnout speed as 95mph and the Down Line turnout speed as 85mph.

[paul7575]

That basically confirms what I copied from the track access application, in post #10 of the thread ^^^.

I'm still assuming that the 85 mph turnout is from the down flyover route - and that's what really needs confirmation if you still had access to the drawing... 

If it really was a new down line parallel to the up line surely they'd also be mentioning a high speed crossing, or the modern equivalent, ie a pair of turnouts providing a route across the up line.  [But if this was being installed there'd be no point in upgrading the existing trailing crossover, IYSWIM.]

As it stands the TAA only mentions one new facing 50 mph crossover, and the existing trailing crossover being upgraded from 15 to 50 mph.

Paul

[SandTEngineer]

The existing flyover Down Line is retained.  The repositioned Up to Down trailing crossover will be 50mph (in the Down Direction).  The new Up to Down facing crossover speed is unfortunately not shown on the plan I have seen but the Up direction protecting signal (BS104) has flashing aspects in rear on repeater signals BS104R and BS104RR (the latter being a new Outer repeater signal) therfore it is safe to assume that the turnout speed will be significantly high.

[Chafford1]

Probs because they'll be extra trains running on higher levels, resulting in more sight, light and noise pollution for local residents. And the trains will be going at 100 mph (or near that).

I hope they quadruple track the area between the junction and West Ruslip (3 tracks at the mo) so that there is a big enough loop for the stoppers to be overtaken by the expresses (plus a margin for some delays)

I also really wish they'd put back in the fast lines at Gerrards Cross and Beconsfield etc; I was stuck behind a stopper once all the way to Princes Risborough - could have overtaken it if BR^▸ (British Rail(ways)) hadn't ripped up the loop lines. (of course, the person really responsible was the bright spark at Marylebone signal box who let a stopper out of just before several expresses!)

Talking of a diff junction: Does anybody know whether the flyover at Aynho will be retained for flexibility? I'm assuming that this junction's remodelling will have to start soon - quite a large project!

Gerrards Cross would require a great deal of work to put the track back to it's pre 1990 layout. Beaconsfield would be easier but Chiltern have instead decided to reinstate the 'Up' though line at Princes Risborough.

[SandTEngineer]

The new Through line at Princes Risborough is going to be bi-directional.

[Chafford1]

The new Through line at Princes Risborough is going to be bi-directional.

That's news to me. The Network Rail Supplemental Agreement refers to a new 'Up' through line.

Construct new up through up line on existing formation at Princes Risborough station, Current up
main at station becomes up platform loop. Install 40 mph facing crossover north of station;
Line speed to be raised to 85 mph on both main lines through station, rising in stages to 100 mph
either side;
Amend signalling to suit revised speed and retain 3 minute headway south of station; some additional signals to be added north of station to reduce current 5 minute headway to 3 minute headway where useful;


Perhaps someone can confirm.

http://www.networkrail.co.uk/browse%20documents/track%20access/2%20completed%20consultations/2009/2009.10.27%20chiltern%20railways%2073rd%20supplemental%20agreement%20-%20consultation%20closed%2023%20november%202009/form%2022%2073rd%20for%20eg3.pdf

[paul7575]

What is suggested isn't that odd, the new line could still be bidirectionally signalled even though the track geometry is designed to make its primary use the up through line, ie the newly named 'up through' is the straight ahead route through the S&C^▸ (Settle and Carlisle ) at full line speed, and the up platform loop requires the much reduced speed. 

As far as an aerial view of the existing layout shows there will still be crossovers either side of the station (one is quite a way south) to allow a down train to get onto the up through.  The main difference is that in the up direction, a platformed train can be passed at line speed, so normally timetabled overtaking would be practical, in the down direction it would just add another option to increase operational flexibility during perturbations?

Paul

[IndustryInsider]

Paul is probably right.  I'd be surprised if the through line wasn't bi-directional purely because the current Up line already is and so the crossovers (or their replacements) would allow the move to take place, so it would be silly not to include the signalling for it.

[SandTEngineer]

All three lines in the station will be reversibly signalled but the Down Main will only be for Up terminating trains to the platform (However, trains will be able to shunt out from there to a 'Limit of Shunt' signal on the Down Main approaching from the South).  The use of the terminology is only for line identification purposes and is used to define the predominate direction of traffic.  This is irrelevant for operational and signalling purposes.

If I get some time I will do a sketch of the new layout and signalling.