Easier Splitting/Joining?

[styles]

Assume these are the people: https://news.railbusinessdaily.com/...olutionary-dynamic-train-coupling-technology/


They've coupled 1 pair of wagons in 1 test run in June this year. Notably the speed this test was carried out at was omitted from the article trumping it's success:

Forgive me if a lot of their well-prepared publicity feels a bit too good to be true. This system feels like it could only release meaningful capacity in areas that have lots of spare route capacity and limited yards and terminal capacity.

Let's take this line:


First, what they don't say - Information Systems (planning, operation, traffic management etc) and Rolling Stock are conspicuously absent from the 'no modifications' line. Cost is also not mentioned. However, all are solvable with the right will.

Then onto what they do say: infrastructure and signalling systems will need modification to allow trains into blocks with moving trains (Currently only allowed in the UK by permissive (conventional) or on-sight (ETCS) MAs). Signalling sections will need amending to allow trains to actually catch up under Permissive aspects. Yards, terminals, loops etc may need modification to accept longer trains if the cargo load isn't reduced. Signalling systems will also need modification to handle trains to split on the move (especially ARS-type systems). Infrastructure may need modification to allow storage of the DC units in suitable places for shunting and marshalling. Regulations will need amending to allow the necessary changes to the signalling systems, and appropriate operational procedures for events such as decoupling failure, 1st train emergency stop, portions arriving in the wrong order, etc.

Assuming that they are planning for a loco to be marshalled mid-train with a driver sitting in their from the last stop before splitting, why not just split at that stop?

TLDR: In order to make this work, you'd need the DC units to be autonomous/ATO-controlled locos (at least for short distances) and CBTC/ETCS L3 or better signalling system on the mainline.

An interesting concept, but one that when you look past the 'cool factor' quickly collapses against it's own assumptions.

Didn't say it was coming soon, but I'd bet money that it will eventually make it to market. I'm sure there were people saying 4G in tunnels wasn't possible when that was first floated, or nobody would ever need more than 640KB RAM...

 

[Nottingham59]

Surely it makes more sense to do the split/join at the same place?

In general yes. But joining two HS2 units at Stoke risks blocking the line if one of the two units is delayed. And I think it might be deemed necessary to lenghthen the Up platform at Stoke to 420m. That will cost, so unlikely to happen soon; I understand they've even cancelled plans to lengthen platforms at Crewe, so spending on Stoke is not going to happen.

My thinking is that re-joining at Interchange wouldn't need any new infrastructure north of Handsacre, and Interchange was designed to handle 18tph, so will have plenty of spare capacity during Phase One.

EDIT: Presuming that HS2 signalling will allow trains to join at Interchange.

 

[zwk500]

Didn't say it was coming soon, but I'd bet money that it will eventually make it to market.

See my TLDR. It's not impossible, but some of their claims about being no-intervention are highly questionable. With advances in signalling technology, very possible at a future date.

I'm sure there were people saying 4G in tunnels wasn't possible when that was first floated, or nobody would ever need more than 640KB RAM...

I'm not sure how those are particularly comparable to a system allowing, in effect, a controlled collision between vehicles.

 

[cle]

If you ran 2x 3-5 car units through Castlefield, candidates might be combining the Barrow and Windermere services into one, splitting at Lancaster. Relatively free from the busiest parts. Preston could work for other services.

I do remember talk of Liverpool and Manchester to Scotland being combined at Preston too, to make it hourly for Liverpool, unsure also hourly split for Glasgow and Edinburgh. That was certainly planned for HS2 before all the cancellations.

 

[zwk500]

In general yes. But joining two HS2 units at Stoke risks blocking the line if one of the two units is delayed. And I think it might be deemed necessary to lenghthen the Up platform at Stoke to 420m. That will cost, so unlikely to happen soon; I understand they've even cancelled plans to lengthen platforms at Crewe, so spending on Stoke is not going to happen.

My thinking is that re-joining at Interchange wouldn't need any new infrastructure north of Handsacre, and Interchange was designed to handle 18tph, so will have plenty of spare capacity during Phase One.

My thinking was do the split/join at Interchange, not Stoke. Lengthening Stoke is extremely unlikely to happen given the layout and geometry. Yes it's an extra path across Colwich but you could send the Macclesfield terminator via Stafford if you really wanted to (or split the Macc train off a different service).

EDIT: Presuming that HS2 signalling will allow trains to join at Interchange.

HS2 Signalling will be ETCS level 2, so joining trains will require an On-Sight Movement Authority. I'm not a signalling engineer, and the handbook I have read is not clear if this would need additional data or logic in the interlocking, or addtional balise groups trackside. The suggestion is that On-Sight MAs don't require anything additional by themselves if Full Supervision is available, but that setting ETCS up to automatically offer the OS MA to the driver for attachment or platform sharing moves would be would be something specifically authorised at specific locations (like permissive working currently is).

I'm sure a signalling engineer can correct me soon enough.

 

[Bletchleyite]

If you ran 2x 3-5 car units through Castlefield, candidates might be combining the Barrow and Windermere services into one, splitting at Lancaster.

I'm all for this idea, but it wouldn't actually reduce the number of trains through Castlefield! There isn't a lot that doesn't need to be full length now, just the Southport really (which could be moved out to Vic as there's nothing sensible to pair it with).

 

[Topological]

The theoretical aim was you could have trains from Wigan, Blackburn and Preston every 15/20 minutes all combining and running in one path to Manchester. The effect of increasing the number of services from each place without needing more paths in Castlefield has the potential to really increase rail use.

If all you do is join existing services then you have issues with one portion being missing and not being able to run.

This speculative thread was about whether it could work to let whatever trains join up and move together in the next Manchester path.

Were money no object, you could even have 2-cars arriving at Bolton (say) and then run together every 10 minutes, especially if the only other Castlefield trains were the Ordsall Chord and CLC trains. A set of spare 2-cars would sit near the Aiport to handle longer term imbalances (Note this is a money no object solution) and where over length sets came in then one could either remain at the airport platform when the rest went back out again, or head to the storage siding.

 

[Nottingham59]

Yes it's an extra path across Colwich

But that's the problem. Colwich/Shugborough is the limiting factor. Any extra path through Colwich means one path less for other services.

you could send the Macclesfield terminator via Stafford if you really wanted to

I'd not thought of that. Via Stafford northbound and via Hixon southbound would reduce conflicts at Colwich. I trust that someone in NR is modelling these options for when HS2 phase 1 gets to Handsacre.

 

[HSTEd]

TLDR: In order to make this work, you'd need the DC units to be autonomous/ATO-controlled locos (at least for short distances) and CBTC/ETCS L3 or better signalling system on the mainline.

Of course, ETCS can be potentially made to function with very short blocks indeed, without being actual moving blocks.

The pseudo-permissive section could be a very short distance, which would cut the time loss substantially and limit the risks of accidents, although I really can't see regulators going for joining on the move in any case.

(What happens if the front train initiates an emergency brake application during the 'closing up'? How fast can the trailing train react?)

 

[Fawkes Cat]

The theoretical aim was you could have trains from Wigan, Blackburn and Preston every 15/20 minutes all combining and running in one path to Manchester. The effect of increasing the number of services from each place without needing more paths in Castlefield has the potential to really increase rail use.

So what happens to passengers on the train that arrives late at the join up point, and so (a) misses the join up and (b) presumably can't run through Castlefield?

 

[Magdalia]

But to me the answer is to run longer units.

If ATW want to run trains through Castlefield, they should be required to run at least 8-car trains, or terminate at Victoria. Four-car EMR units should terminate in the main shed at Piccadilly. Similary, if Lumo want to use scarce capacity on the southern ECML, they should run 10-car trains. EMR should have ordered 234m-long standard 9-car IETs, rather than bespoke 5-car 810s for the Midland Mainline. And Cross Country should be running longer trains too.

It's entirely wasteful for the country to allow short trains to be run on congested railway infrastructure.

Absolutely, the simplest and quickest way to make better use of existing infrastructure us to run longer trains. At Piccadilly another example is the Birmingham service which should be 8 car EMUs not 4 and 5 car DMUs.

 

[The Planner]

I'd not thought of that. Via Stafford northbound and via Hixon southbound would reduce conflicts at Colwich. I trust that someone in NR is modelling these options for when HS2 phase 1 gets to Handsacre.

For a long long time, including the parts that then went into the bin when Rishi canned it.

 

[PeterC]

Deleted

 

[zwk500]

Of course, ETCS can be potentially made to function with very short blocks indeed, without being actual moving blocks.
The pseudo-permissive section could be a very short distance, which would cut the time loss substantially and limit the risks of accidents, although I really can't see regulators going for joining on the move in any case.

Under Level 2 its still a fixed block system though and to enter an occupied section requires a transition from a Full Supervision MA (ending at the last EoA prior to the occupied block) to On-Sight MA, limited to 40kph.

Tbh itll be far easier to put in more EoAs and run 2 freight trains on minimum headway than try and convince the regulators to permit controlled collisions.

 

[Tester]

I can't see why it would be necessary to move a train after uncoupling it before the actual departure. Our procedures don't involve closing the doors before attaching another train, nor stopping before attaching to another trainset.

Sadly, we have taken a different path.

On the bright side, it could be worse. I (along with all passengers) have been evicted from the front portion of a joining train while the attachment was made. Luggage was allowed to be left on board 'at passengers' risk'. On mentioning to a station staff member that it seemed a bit over the top, he was horrified and said that staying on board would be far too dangerous.

Never underestimate culture!