Wasting my life at Wembley Park

By chance I was discussing this very subject with the Met Line Controller, the other evening and we were bemoaning the fact that a golden opportunity had been missed to do something about it when the direct connection from platform 6 to Neasden Depot was put in.

The restrictive nature of the signalling on the apporach to Wembley has not changed in more than twenty years but other changes have made matters worse since then.

There are several factors which affect how the signals work:

• Full speed approach to both platfrom 5 & 6 requires the line to be clear to a point beyond where the fast and local lines converge and the points at the convergance must be set for the relevant line. This means that you cannot have trains approaching both platforms 5 & 6 at full speed at the same time
  
• There is also a slow speed approach to platform 5 which allows simultaneous full speed approach to platform 6. There is no slow speed approach to platform 6. This means that a train cannot enter platform 6 at the same time as one is departing platform 5 (or even if one has been signalled into platform 5 with the full speed approach).
  
• The signalling is computer controlled. When faced with a choice of which train to route next the computer uses Turn Control to evaluate which train to route when. This is based on the timetable and the computer will often give precedence to the next timetabled train. So a typical example: Off peak trains on the fast line are due through Wembley three minutes behind the Aldgate service on the local line. Imagine the Aldgate is 1½ minutes late and the fast train is 1½ minutes early. In other words they are side by side approaching Wembley. Both trains call at Wembley. The sensible thing to do would be to signal the fast train into platform 6 with the full speed overlap and bring the Aldgate into platform 5 with the slow speed approach, then once both trains have arrived signal the Aldgate train away; we want to minimize the delay to this train so it does not miss its path into the city at Baker St. What actually happens is that the computer decides the Aldgate is the next timetabled train and signals it into platform 5 with the full speed approach and the signals it south. This results in the fast train being stuck at the home signal (MG2B) until the Aldgate is well on it way to Neasden.
  Now you may wonder what the operator who is supervising the computer is doing. Well apart from anything else at the very least, even at the busiest time he will also be looking after the Baker St area and may have his attention on that. There is very little warning for him of trains approaching Wembley; trains on the local are not seen until they leave Preston Road and as soon as they do the computer will clear the signals all the way into Wembley if it can as described above.
  There is a bit more warning of fast trains, they appear on the diagram as soon as they have crossed the West Coast Main Line. However even here the computer will try to clear the signals into Wembley as soon as the train appears, if it is the next timetabled train. Many is the time that a train is just arriving in Wembley platform 5 (on the slow speed approach because it is no the next timetabled train) and a slightly late train appears on the fast and 'nicks the road' ie the train in 5 cannot now leave as the computer has signalled the fast train into 6 (remember no slow speed approach into 6)
  

Now this is how it has been for a long time, (and I hope it makes sense to you) but there are a couple of things that have changed.
When the signalling was installed Mets could run up to 70 mph, but now they are restricted to 50mph. This means that in the situation where a fast train has been routed while only just having crossed the WCML it now takes longer for the train to clear Wembley.
The second change is the timetable. Nowadays all fast trains during the off peak call at Wembley, but this was not the case when the signalling was put in. Then it didn't make much difference if a fast train was stopped north of the station, or in a platform while waiting for a local train to get out of the way as it wasn't going to call at Wembley any way. Now the fast train has to wait outside, then run into the platform to carry out station duties. Off peak, fast trains also have more time to run from Harrow to Wembly than they really need and so invariably arrive a minute or two early and therefore have to wait on the Aldgate service.

What was the situation like before twenty years ago out of curiosity?

Yes, I remember trains terminated / started in the peaks at Liverpool Street, Moorgate, and Aldgate. The bay at LS has obviously long gone.

The Loco changeover point was at Rickmansworth. When the electric rails were extended to Amersham, steam took over at Ricky still because there were no facilities at Amersham.

I never saw the bay at Liverpool Street, I guess its never going to return either. I believe, before the bay was taken out, it was thought that the entire Met service couldn't be reversed at Aldgate. Stepping back was introduced at Aldgate to compensate.

Yeah, wasn't stepping back introduced in the mid 90s? The bay was removed to provide offices for the Broadgate building work I think.

It was indeed removed for Broadgate.

When I was a boy (late 1970s/early 1980s) I remember my father - a now-retired Met driver based at Rickmansworth - taking me in the cab with him (no names, no pack drill) from Chesham to Liverpool Street. I think it was only the peak-time Cheshams that started from/ran to the bay at Liverpool Street but I could be wrong.

THC

Absolutely; sorry didn't make myself clear there! I was wondering what the signaling was like twenty years ago on this section. Harsig said "the signalling on the apporach to Wembley has not changed in more than twenty years": Was it rationalised at this point in time? Or was the signaling there previously just as restrictive?

Sorry about that!

The only last big change I can think of was the closure of the Signal Cabin and the move to remotely operated IMR.

There were 2 all-stations Watford-Moorgate trains in the peak flow direction. The Amersham branch, in addition to fasts to the City which ran non-stop between Moor Park and Finchley Road, also had all-stations to/from Baker St. Most of the Watford peak flow services were all-stations to/from Baker St, with some semi-fasts to/from Aldgate.
The Uxbridge branch had the most variety. All stations to/from Aldgate, all stations to/from Baker St, and semi-fast to/from Aldgate in the peak flow direction. Especially during the morning peak there were also additional "down" trains between Baker St and Harrow. Plus the semi-fasts until 1975 ran non-stop between Rayners Lane/North Harrow and Finchley Rd.