Metropolitan fast train running on slow line

[Daniel]

There are hundreds of switch diamonds across the national network, they aren't particularly liked and they are probably more prone to failure in extreme temperatures but I've never before heard of a case when they are taken out of use as a precaution in the relatively modest temperatures we've had in the last few days. So I ask again what's so bad about these ones here?

I say this to no detriment to any staff working for National Rail routes - but TfL seems to care more about proactively avoiding failures and having trains stuck in section. Other lines also remove points from service during adverse weather - I'm aware of some at East Finchley and Finchley Central on the Northern Line, for example. We run a high-frequency metro style service (I am aware less so on the North end of the Metropolitan Line). LU isn't afraid to cause a 4 minute delay on a fast train to avoid having a points failure, a part-suspension, a train stalled in section requiring a wrong direction move, a suspension to secure points, or a train to track detrainment. On national rail routes you'd have to justify the 4 minute delay when the points failure hadn't yet occurred - LU doesn't have delay attribution in the same extreme way with a cost involved for that 4 minute delay, which has been caused as it has been deemed in the best interest of the overall service.

 

[edwin_m]

I say this to no detriment to any staff working for National Rail routes - but TfL seems to care more about proactively avoiding failures and having trains stuck in section. Other lines also remove points from service during adverse weather - I'm aware of some at East Finchley and Finchley Central on the Northern Line, for example. We run a high-frequency metro style service (I am aware less so on the North end of the Metropolitan Line). LU isn't afraid to cause a 4 minute delay on a fast train to avoid having a points failure, a part-suspension, a train stalled in section requiring a wrong direction move, a suspension to secure points, or a train to track detrainment. On national rail routes you'd have to justify the 4 minute delay when the points failure hadn't yet occurred - LU doesn't have delay attribution in the same extreme way with a cost involved for that 4 minute delay, which has been caused as it has been deemed in the best interest of the overall service.

Thanks for the reply. Interesting thoughts here.

Another reason might be that few of the switch diamonds on Network Rail are part of fast-slow crossovers - there is usually flexibility in siting those along the line, so they will be put where there is space for a less complex set of single switches. Instead they are usually associated with physical divergences of tracks, where leaving the switch in one setting would involve closing one of the routes, probably with immediate suspension of some services.

 

[Surreytraveller]

Whilst I am well aware that a fast caught up behind a slow would not lose much time in the context of recovery time, 4.5mins is a lot in the context of the train being a fast train. So as queried before, would it not make sense to just run anything which is going to get caught behind a slow, all stations anyway as the time difference would not be much? (Note that a train which has a "clear" run would remain fast). I know passengers may get annoyed at a fast train becoming all stations from Harrow at the drop of a penny, but the driver should be instructed to say that as we have to use the slow lines, the train would be caught up behind an all stations and be going very slow.

Some options:

1. Have a hot weather timetable in place which makes amendments to when fast trains depart Harrow on the hill (obviously accounting for Chiltern trains) so that as many as possible get a clear run. I know it needs to be put in place quite last minute but we are only talking about minutes here and there.
2. Give fast trains the priority at harrow if there is one due either just minutes after the all stations or, a stopper and fast get to harrow at the same time.
3. RENEW THE POINTS!!!!!!!!! (So that this isn't an issue). Are there even any other points on the network which have such an issue (which cause significant changes to operations?)

Note with everything I've said above, I realise I am only talking about the evening peak, but the same would apply to the morning peak around the Moor Park junction where the Watford branch diverges. (Potentially a bigger issue for fast trains being slowed as people are getting to work!)

Running the fast behind the stopper probably IS the special timetable, knowing it'll recover the time at Amersham.
If you delay the stopper, that will probably have a worse effect at other junctions to other trains. And maybe the stopper doesn't have as much recovery time.

 

[Taunton]

The set of points is not very bad - they are a different type of points. Moveable angle points are fitted at this location, allowing faster running for trains non-stopping (Chiltern). However, they are more prone to failing to detect owing to expansion so they are taken out of use to prevent delays caused by their use when a warning is given.

So, special points installed, doubtless at some cost, to allow fast running ... which have a feature that means fast running has to be abandoned.

Am I being unfair?

 

[zwk500]

So, special points installed, doubtless at some cost, to allow fast running ... which have a feature that means fast running has to be abandoned.

Am I being unfair?

Depends how often the mitigation plan needs to be activated.

 

[Daniel]

So, special points installed, doubtless at some cost, to allow fast running ... which have a feature that means fast running has to be abandoned.

Am I being unfair?

Yes, you are, because you're not considering that the fast running they allow is for Chiltern trains, which I stated earlier, whereas those which are affected by their removal from use are Metropolitan line trains which only utilise the fast lines during a small proportion of the day.

Also, they're special in terms of London Underground, but not in terms of the UK national rail network. Choosing MAs or normal points, I doubt there would be a significant cost difference as each set are specially manufactured for each location anyway. I again highlight that these are not new points which have been recently installed but that MAs have been used at HotH for decades at least.

 

[bluegoblin7]

Yes, you are, because you're not considering that the fast running they allow is for Chiltern trains, which I stated earlier, whereas those which are affected by their removal from use are Metropolitan line trains which only utilise the fast lines during a small proportion of the day.

Also, they're special in terms of London Underground, but not in terms of the UK national rail network. Choosing MAs or normal points, I doubt there would be a significant cost difference as each set are specially manufactured for each location anyway. I again highlight that these are not new points which have been recently installed but that MAs have been used at HotH for decades at least.

I was avoiding commenting if only because @Daniel (and others) have covered most of the facts and it's still descending into the usual wibble, but just wanted to add that this is far from a 'new' issues and various mitigations have been tried over the years to reduce the failure rate of these points - including, at one stage, a sprinkler system. The only reliable mitigation to avoid the points failing is to take them, and two similar sets of points south of Harrow, out of service when the rail temperature gets too high. The resulting delay is negligible, in part due to the competent work of controllers and signallers in regulating services - during the peak there's usually only three trains between around 4 and 7 that have to follow a stopper - and in response the full service keeps running. When (not if) these points fail in hot weather it is usually a minimum of a 30 minute suspension before services start running again, with the resolution being to simply take the points out of use anyway. The only other solution would be to have a cessation in services for about the same time to manually adjust the points whenever the weather started to warm up - which is the lesser of two evils?

Of note, one of the sets of points affected were out of use for around 9 months last year causing all Amersham & Chesham trains to run semi-fast all day. This was largely due to the long lead time for bespoke components. Better to proactively take them out in the first place than risk further damage by hoping for the best. As mentioned, TfL is far more proactive with this sort of thing than the national network, largely due to being its own organisation and being able to best manage delays and infrastructure restrictions without worrying about things like delay attribution.

 

[Taunton]

Yes, you are, because you're not considering that the fast running they allow is for Chiltern trains, which I stated earlier

But what fast running for Chiltern trains do they allow? The timetable time for these, Marylebone to Harrow, and Harrow to Ricky, is just the same as 50 years ago in the 1970s, with old, underpowered Modernisation Plan diesels.

 

[bluegoblin7]

But what fast running for Chiltern trains do they allow? The timetable time for these, Marylebone to Harrow, and Harrow to Ricky, is just the same as 50 years ago in the 1970s, with old, underpowered Modernisation Plan diesels.

Faster than the Met line.

But you've also hit the nail on the head: the top end of the Met is still signalled for GCR expresses.

 

[chiltern trev]

Chiltern trains do not have to slow down to pass over this junction and the lack of rail gaps for flanges means a smoother ride, quieter ride and less wheel hammer effect on the track.

 

[12LDA28C]

Chiltern trains do not have to slow down to pass over this junction and the lack of rail gaps for flanges means a smoother ride, quieter ride and less wheel hammer effect on the track.

Speed over the junction is 35mph on the Up and 40mph on the Down so effectively there is a restriction.