Could the Elizabeth Line be speeded up by reducing dwell times

[DynamicSpirit]

Split from this thread: https://www.railforums.co.uk/threads/southern-suburban-services-slower-than-50-years-ago.290196/

This is a response to a question of why the Elizabeth line has frustratingly long dwell times of up to 60 seconds in the core, which must be considerably slowing the services down.

Yes:

a) to absorb small delays
b) to deal with future growth without having to rewrite the (very complex) timetable.

I can see the need to absorb delays, but I'm dubious and puzzled about the need to guard against rewriting the timetable: Yes, the timetable is complex West of Paddington because of the interaction with National Rail - and this seems to have resulted in a complicated skip-stopping pattern. But East of Paddington, there is no need to work with any other services at all on the Abbey Wood branch, and it doesn't look like there is to any significant extent on the Shenfield branch either since the Elizabeth Line uses a separate set of tracks from the faster Anglia services. East of Paddington, all trains stop everywhere: The timetable is pretty simple, so the main complexity issue would appear to lie in the need for a train to arrive at Paddington from the East at the right time to slot into the paths towards Heathrow/Reading. With a turn-up-and-go all-stops service feeding those trains to Paddington, it doesn't seem a particularly complex problem to do that even if the services are speeded up a bit.

I'd also note that the Elizabeth Line already runs a separate (and more frequent) peak hour timetable compared to the off-peak timetable, so if the issue is more dwell time needed in the peaks, that shouldn't be a barrier to speeding up at least the off-peak services by reducing dwell times.

 

[Phillipimo]

This reminds me of a 'Diamond Geezer' blog where he found:

Whitechapel to Paddington
Crossrail: 25% of the 13 minute journey is spent not moving
H&C tube: 25% of the 26 minute journey is spent not moving
205 bus: 50% of the 64 minute journey is spent not moving

diamond geezer

diamondgeezer.blogspot.com

The Liz is so fast I don't think saving a couple of minutes on dwells is worth it for the reduced resilience.

 

[Horizon22]

Don’t think this would really be a huge win. You’d save maybe 2-3 minutes which overall isn’t going to make a massive difference to anyone.

You also have to remember that this would impact the timetable for trains departing and arriving - the latter being more of a concern - into Westbourne Park and Abbey Wood with potential for sidings/platform occupancy clashes if trains started arriving at destination earlier. You’ve also got to slot trains into the right order at Paddington - where possible - which includes the Heathrow - Shenfield service. This would probably lead to the aforementioned rewrite.

It may feel a little pedestrian at times but CBTC can still automatically reduce dwells during either small delays of 1-2 minutes and even more during late running, and there are ways the signalling can also do if trains are not running in booked paths which speeds everything up for a time. You could probably rewrite the timetable but that seems like a massive piece of work for limited gain. Nobody is not taking the Elizabeth line due to extended dwells, as the alternatives are still slower. The timetable in the core section has some slack, which is no bad thing considering the potential for delays from the GWML/GEML.

 

[Class 170101]

But East of Paddington, there is no need to work with any other services at all on the Abbey Wood branch, and it doesn't look like there is to any significant extent on the Shenfield branch either since the Elizabeth Line uses a separate set of tracks from the faster Anglia services.

Sorry but you are showing naivety here.

Whilst Elizabeth Line won't be running on the MLs east of Stratford (most of the time) they do have interaction with Greater Anglia and Freight at Forest Gate Jn which will impact on the T&H if they Freight slots don't line up from Barking / Woodgrange Park across to Channelsea Jn and beyond.

Also Greater Anglia use Ilford Depot which means they run ECS moves to / from the depot on a daily basis and on the Electric Lines. This means the Elizabeth Line Timetable needs to allow for slots for moves into / out of Ilford Depot for said ECS moves. ECS moves are also run by Freight Operators into the depot for various works at Ilford Depot. Just look at Realtime trains.

 

[dk1]

Sorry but you are showing naivety here.

Whilst Elizabeth Line won't be running on the MLs east of Stratford (most of the time) they do have interaction with Greater Anglia and Freight at Forest Gate Jn which will impact on the T&H if they Freight slots don't line up from Barking / Woodgrange Park across to Channelsea Jn and beyond.

Also Greater Anglia use Ilford Depot which means they run ECS moves to / from the depot on a daily basis and on the Electric Lines. This means the Elizabeth Line Timetable needs to allow for slots for moves into / out of Ilford Depot for said ECS moves. ECS moves are also run by Freight Operators into the depot for various works at Ilford Depot. Just look at Realtime trains.

Was very impressed and felt almost nostalgic to see a Freightliner moved onto the DE at Ilford so I had a clear run on the DM the other week.

 

[NCT]

The EL is only in its 3rd year of operation and there's an awful lot of development along the line still waiting for people to move in, then there'll be all the HS2 traffic.

What feels like generous dwell times today won't be generous in 10 years time.

 

[dk1]

The EL is only in its 3rd year of operation and there's an awful lot of development along the line still waiting for people to move in, then there'll be all the HS2 traffic.

What feels like generous dwell times today won't be generous in 10 years time.

Already planning to go up to 26 or 28 tph in each direction. One option is to divert the peak Gidea Park-Liverpool St (High Level) into the central core.

 

[Horizon22]

Already planning to go up to 26 or 28 tph in each direction. One option is to divert the peak Gidea Park-Liverpool St (High Level) into the central core.

Those residual services are very popular! But yes ultimately it would be ramping 14tph from Abbey Wood and 14 from Shenfield / Gidea Park to accommodate.

The core can theoretically have 30tph with extended 11-car trains but having suitable destination platform and line capacity on the GEML and GWML is the bigger challenge.

It is impressive that high peak trains can be completely crush loaded by Whitechapel or even Canary Wharf considering 3 years ago it didn’t exist (yes GE services were still busy but it’s not quite the same on a battered 315!). Luckily there is a lot of churn at Liverpool St and Farringdon.

 

[dk1]

Those residual services are very popular! But yes ultimately it would be ramping 14tph from Abbey Wood and 14 from Shenfield / Gidea Park to accommodate.

The core can theoretically have 30tph with extended 11-car trains but having suitable destination platform and line capacity on the GEML and GWML is the bigger challenge.

It is impressive that high peak trains can be completely crush loaded by Whitechapel or even Canary Wharf considering 3 years ago it didn’t exist (yes GE services were still busy but it’s not quite the same on a battered 315!). Luckily there is a lot of churn at Liverpool St and Farringdon.

Couldn’t of put it better myself