Great Western Coffee Shop

I can remember way back that bidirectional running was installed - perhaps at great cost - on lines such as Swindon to Didcot, with the tag line that it would allow faster trains to overtake slower ones.   Thems was the days when there was a lot more slow freight and a lot less express passenger traffic, so it made more sense then.

Which double tracked sections were / are set up for bidirectional running, and how much is it used these days?

On the GWML I think it's from Foxhall Junction (west of Didcot) to Bedminster and Wootton Bassett Junction to Chipping Sodbury.  Lots of other smaller sections around stations as well of course.  Didcot to Aynho Junction is planned over the next few years as part of the Oxford Corridor Enhancements programme.

The longer sections aren't used too often and are more for engineering works and failed train scenarios than overtaking moves due to the quite long signal sections and the likelihood of a train wanting to come the other way.

I think the only thing that isn't (or can't be?) done at Swindon is a Paddington bound service from Platform 4. 1 and 3 are pretty much constantly used in a bi-directional manner.

- Bristol Temple Meads / Cheltenham Spa services are often turned around/restarted from platform 1 at Swindon if there are (major) problems towards pad.
- The transwilts service sometimes uses plat 1 instead of plat 2 if either of the services that use 2 are late.
- Weekends usually see late night services not using 4, etc.

My point being that the bi-directional working at Swindon has more than likely saved a lot of problems with the works and signalling problems we've been inflicted with recently.  :)

I have once been on the seawall stretch in South Devon when my train - a late running service from Paddington - was routed onto the up line at Dawlish Warren to overtake a stopping train.  We overtook it just after Dawlish and then crossed back over to the down line just after Teignmouth station.

I'm not sure about heading west from platform 1. Was on a 3 hr late service that was making its second attempt to depart Swindon heading west having been turned back before WB because of a fatality. It had arrived back into platform 1, and was explained to me by FGW staff that they had to then head east before reversing back into 4 (think 3 was occupied), as 1 westbound onto the main line isn't signalled.

As for 4 eastbound, there are certainly full signals at that end, though I've never seen them used.

I think 1 must be signalled westbound as TransWilts services do, on occasion, leave from there.

As for Platform 4 eastbound, there is certainly a main signal at the London end of the platform, but what routes are available from it I am not sure.

Looking at SimSig, you can, from P4 eastbound, access the down yard, continue bang road all the way to Didcot, or cross back over to the Up main at Bourton or Uffington.

To have accessed P4 in the wrong direction you would need to have crossed from Up to Down at Wootton Bassett West if approaching from the Badminton Line, and at Wootton Bassett Junction if approaching from Box.

The Down Main between Southall East and Airport Junction is signalled for bidirectional running to allow Up HEx trains to get past any blockage affecting the Up flyover line. A few months ago my regular morning Paddington-bound Turbo was brought to a stand on the Up Main to the west of Southall while an Up HEx overtook it on the Down Main.

Similarly I have seen westbound trains stop on platform 4 (Up relief) at Hayes and then pull away, overtaking the westbound train stuck for whatever reason on Platform 3 (Down relief).

When the 'dynamic' Axminster loop was commissioned in late 2009 it was signalled as bi-directional on both lines. Great. However the re-instated up line was designated as the down line and the existing single line (the old down) became the up line. Much worry about confusion when dealing with faults/emergencies lead eventually to a decision to trains running on the 'correct side' and after some delays the up became the up and the down, the down!

An electrical fault then meant that the up trains once again used the down line and down trains the up for some time. Eventually the problem was rectified and I am glad to report that (AFAIK) the up trains now run on the up line and the down the down as they should (at least for the moment).

All clear? Best keep an eye on the departure boards if using Axminster Station.

To add to this the original signalling allowed wrong road running from Airport Junction (Down Heathrow) right through to Southall East Jn (site of the crash) on the Down Main.

Recently a trailing crosiver has been installed between the Down and Up Mains just East of Hayes station to limit the length/time running wrong line.

 
During my commuting days I've overtaken a Down Train using platform 4 at Hayes. One of the problems with this is that the crossover to the Up Relief is right back at Southall West so it involves quite a length of Wrong line running. This also applies to trains termianting in Platform 5 at /Hayes.

Similar overtaking of down trains can be carried out at Slough Platform 5 and Maidenhead Platform 4. in both cases the length of wrong road running is less than at Hayes. Also   at Twyford Platfrom 4 although the length of long line running is longer.

Before platform 6 was taken OOU Slough was unique in that you could have a train in all six platforms and blow one whistle and they could all move off simultaneously. But not quite as spectacular as a steam hauled double departure from Alexisbad.

I've done quite a few wrong-direction moves during my 25 years as a commuter, not just the ones mentioned here at Hayes, Maidenhead and Twyford. I've done crossover shunt moves on out-of-course terminating Turbos which involved DR to UR at Maidenhead West and UR to DR at Twyford East. I believe both of these are non-signalled moves and we should have been detrained beforehand, is that right?

I've also managed to do all 4 lines in the Up direction between Taplow and Slough West! A derailment to the west of Taplow resulted in an Up trip along the DM from Maidenhead East and a loco fire on the DR also to the west of Taplow resulted in our Turbo being sent back east along that line. In both cases of course these were emergency non-signalled moves. (The former of those occasions was in the late 1980s and involved a journey behind a Class 50.)

I was at Newbury a couple of weeks ago and a Bedwyn service departed from the up platform.

As far as I could see it crossed to the down line just west of the road bridge just to the west of the Station.

There are a couple of evening services to Bedwyn which start from platform 2 at Newbury after waiting for a West of England service to depart from platform 1.

Usually, if there's a move that is signalled by subsidiary or position light signals rather than 'main aspects' then passengers should be de-trained, but if there's no sensible way of doing that then the moves can be done with permission of the signalling supervisor.  Sometimes that might involve clipping and scotching points. 

Don't forget that in power signalled areas the point motors have an integrated FPL. So so long as the signalman has full detection both ways  then it's safe to run over them in the facing direction. There are also usually indivdual point switches so the that each point can be changed by itself rather than when it's part of the route being set. The interlocking still apllies so it should be safe to make the moves with pasengers on board.

Detection is very sensitive as I know from experience on a private railway where we have a point motor. We lose detection with the slightest maladjustment. If they are not track circuit failures then signal failures are often loss of detection on points. 

There were delays at Swindon at the weekend after the signaller lost detection on a set of points.  When staff on the ground inspected them, they found a crushed drinks can was the culprit.

The WR were very good at not providing FPLs in the point machine on trailing points without a signalled movement in the facing direction over them.  Quite a few sets still around like that :o ;)

....and just to clarify a couple of points ( ;)):

Bi-Directional signalling is that which allows two direction running on the same line within station limits.

Reversible signalling is usually between two distinct spaced out station limits.  In the 'old' days we used to call this SIMBIDS (Simplified Bi-Directional Signalling) which had no, or very few intermediate signals for the reversible direction or FULLBIDS (Full Bi-Directional Signalling) which had intermediate signals parallel to every normal direction signal on the adjacent line.  NR don't allow us dyed in the wool S&T Engineers to use those terms any more >:( ::) :P

That's very interesting S&T I thought the FPL was an integral part of the machine. Presummably it saved a few pounds buying them intially. I can't see it saving much in maintenace as it's a pretty robust piece of metal  and you still have to have full detection.


I remember being told by an S&T engineer at Manchester London Road that they could get it set to detect a cigarette paper between the rails. Probably an exaggeration to impress young railwaymen  but not far short of the mark.

Those strike me as quite sensible descriptions (it does what it says on the tin) - what do you have to describe these as nowadays?