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Old 20th April 2017, 21:18   #331
Bald Rick
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Originally Posted by 43074 View Post
.
I don't understand this, the 2018 peak timetable proposes 2tph Rainham to Luton, 2tph Maidstone East to Cambridge & 2tph from each of Orpington and Sevenoaks to run via the Catford Loop so I don't understand how this forces a 20 minute cycle - can you explain the link here please?

IMO they'd be better off focusing the Kent services on the Catford Loop, any services via London Bridge should run onto the BML because having parallel movements in the London Bridge area (i.e. between Thameslink & Kent lines) sort of defeats one of the key objectives of the whole project.
Your 2nd para sums it up perfectly.

The Kent timetable for services ex Cannon St run on a 20 minute cycle (off peak) and 22 minute cycle (peak). Note this doesn't mean a 3tph service to certain destinations, rather it is train paths that do roughly the same thing in the Metro area. E.g. 1702 Hastings, 1724 Ramsgate, 1745 (46) Folkestone, 1808 Ramsgate all have the same routing.

Trains coming out of the TL core via London Bridge to Kent would have to fit into this cycle. But as we know, the TL trains would be in some form of half hourly cycle. So it won't work, at least not reliably and not without plenty of pathing time. Unless, of course, you completely recast the Kent Metro timetable to fit around a handful of Thameslink services.

Hence why it would be somewhat easier from a timetabling perspective to keep TL services via London Bridge heading down the Sydenham corridor, and anything going to Kent to be routed via Bromley South.

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Old 20th April 2017, 23:11   #332
JonathanH
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Only dozens - why I am not surprised.

What I don't get is why keep to the Dogma of the announced pairings as surely the suggested change would make the whole Southern section a lot smoother to organise. 15 minute paths evenly used would surely help the planning?
There are loads of trains on the Brighton Main Line though and the Thameslink services have never been evenly spread from Brighton because they have different calling patterns. Add to that the issue of pathing a non-stop service to Gatwick and you can see why 15 minute gaps wouldn't actually help planning.

Looking at the consultation document, the Bedford to Gatwick service calls at Norwood Junction so won't have the same running time between East Croydon and London Bridge as the Bedford to Brighton service. At the moment, Bedford departures from East Croydon off peak are 13 / 17 minutes apart (xx25 from Brighton, xx38 from Three Bridges).

If there will be six trains an hour from Redhill to East Croydon, it makes lots of sense for the services to be exactly 10 minutes apart even if two go to Victoria and four go to London Bridge. If they are 10 minutes apart at Redhill and they have different calling patterns, they will be a bit closer to each other at East Croydon.

Whilst we are told that the timetable is starting from a blank sheet of paper, lots of it is fixed by what happens elsewhere eg Arun Valley to Portsmouth / Southampton by times west of Havant. There was also the suggestion that the Quarry line off-peak service south of East Croydon from 2015 is in its future form already. That has Thameslink trains to Brighton departing East Croydon at xx19 / xx26 / xx49 / xx56 so not well spaced.
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Old 21st April 2017, 05:08   #333
Minstral25
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There are loads of trains on the Brighton Main Line though and the Thameslink services have never been evenly spread from Brighton because they have different calling patterns. Add to that the issue of pathing a non-stop service to Gatwick and you can see why 15 minute gaps wouldn't actually help planning.

Looking at the consultation document, the Bedford to Gatwick service calls at Norwood Junction so won't have the same running time between East Croydon and London Bridge as the Bedford to Brighton service. At the moment, Bedford departures from East Croydon off peak are 13 / 17 minutes apart (xx25 from Brighton, xx38 from Three Bridges).

If there will be six trains an hour from Redhill to East Croydon, it makes lots of sense for the services to be exactly 10 minutes apart even if two go to Victoria and four go to London Bridge. If they are 10 minutes apart at Redhill and they have different calling patterns, they will be a bit closer to each other at East Croydon.

Whilst we are told that the timetable is starting from a blank sheet of paper, lots of it is fixed by what happens elsewhere eg Arun Valley to Portsmouth / Southampton by times west of Havant. There was also the suggestion that the Quarry line off-peak service south of East Croydon from 2015 is in its future form already. That has Thameslink trains to Brighton departing East Croydon at xx19 / xx26 / xx49 / xx56 so not well spaced.
Some good points but I don't grasp why having evenly spaced trains cause timetable issues. From a passenger perspective they are very good.

I can understand why if you have different calling patterns you'd get some variations but leaving London/East Croydon where calling is the same should be fine. Then South of East Croydon the slightly different pattern will mean different arrival time but as the stations are evenly balanced (both Brighton trains south of East Croydon have 6 stops (mostly different) for example) it won't be that far out at Brighton.

On Redhill route you point out 10 minute spacing but that is not good for the customer as it becomes LBG/LBG/VIC - OK for VIC as half-hourly, but 10/20 on LBG - from Redhill 98% of passengers either want LBG or VIC but not either.

I'm sure there are lots of other problems in the mix but when the opportunity is to fully rebuild a whole timetable do you leave these issues in place?
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Old 21st April 2017, 05:55   #334
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This is the sort of bewilderingly complex problem that, one day, perhaps an artificial intelligence system will be able to solve better than humans on their own.
Some clever people not too long ago designed a computer algorithm than could beat an advanced human player at Go.

Frankly, that's a doddle compared to automating train planning.
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Old 21st April 2017, 09:37   #335
43074
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The Kent timetable for services ex Cannon St run on a 20 minute cycle (off peak) and 22 minute cycle (peak). Note this doesn't mean a 3tph service to certain destinations, rather it is train paths that do roughly the same thing in the Metro area. E.g. 1702 Hastings, 1724 Ramsgate, 1745 (46) Folkestone, 1808 Ramsgate all have the same routing.

Trains coming out of the TL core via London Bridge to Kent would have to fit into this cycle. But as we know, the TL trains would be in some form of half hourly cycle. So it won't work, at least not reliably and not without plenty of pathing time. Unless, of course, you completely recast the Kent Metro timetable to fit around a handful of Thameslink services.

Hence why it would be somewhat easier from a timetabling perspective to keep TL services via London Bridge heading down the Sydenham corridor, and anything going to Kent to be routed via Bromley South.
Thanks for the explanation, that makes sense.
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