Splitting/joining trains

[mopoona]

Did anyone thing about implementing a functionality that allows users to create lines with MU trains that split or join at a specific station? I would find such a thing very useful.


If there are people interested in using/programming this function, we could share our thought in this topic.

[kierongreen]

It's an interesting idea to simulate some real world situations, however I'm not sure the coding involved (likely to be large) and interface required would be worthwhile.

Did you have specific interface ideas?

[Fabio]

Probably related to this idea, there is also the implementation of ferries and shuttle trains (here transported vehicles could be "appended" to the shuttle/ferry but not shown)

[mopoona]

Yes I have a few ideas. I thought about the following steps for splitting and joining:

The whole process should be done with train lines rather then single convoys:

When one unit of the MU train arrives at the station (where the MU should be joined) it waits there until a train arrives that it can couple with (of a specific line perhaps)? The other unit arrives at another platform of the same station (or the same-> new signals?).
Both units disappear and instead the MU train appears at the platform of the first unit.

Splitting, I think, is easier to implement. When the MU train stops at the station, it disappears. First, at the same platform), one of the units appears. After the first unit is gone, the second appears on the same platform.

This would be a rudimentary way, that doesn't require a ton of new function. As about the interface:

Imagine you define one main route and another hop-on route. Then on the splitting and joining stations, you could set additional values. Lets say you have main route no. 1 and hop-on route no. 2.

On Station X (first direction), you set the value "Join with Line" to "Line 2" for Line 1. Then all trains from Line 1 should wait at Station X to join with one train of Line 2.

On Station X (opposite direction), you set another value "Split to Line" to "Line 2" for Line 1. Line 2 will have Station X as an ending point, with an additional value identifying this station as a splitting/joining station.

There are still a lot of problems to solve. For example how will routing work (the routing system should see both units as individual direct lines). And should there be any maximum waiting times? How may them be implemented.

Any ideas?

[greenling]

mopoona
your idea it´s great.
but i dont know how progress it.

[AP]

Splitting DMUs/EMUS is a fairly modern phenomenon.

For most of rail history, it was more commonly done with slip coaches. If there could be a way for coaches to detach at one platform and wait in a bay platform for collection when a specified train arrives (and terminates), that would be very interesting, since it would reduce the number of interchanges on key long-distance journeys. Picking them up again would be complex, presumably there would have to be a control on how many to stop a train getting too long....

[Fabio]

If coaches detaching were possible, it could be default for freighters, where a convoy reaches a loading station pulling empty waggons, then the engine(s) detaches and pull a string of full waggons to the consumer.

This feat would be nice also for standard, IMHO.

[rsdworker]

sounds very ideal - splitting and joining trains would be nice for me because i can split routes or join routes around cities also ferries could have trains on it or bus

[ӔO]

I recall seeing such a trick by using invisible coaches when they are empty.

I think it would add a lot of realism, but how would you flag where such functions should take place and wouldn't this mean the entire code for convoys will need to be replaced?

[kierongreen]

Yes fabio - any code would probably be similar. You may have a generic convoy carrying type - such that boats and trains can carry trains, lorrys, buses. Surely another use of similar code would be to swap locomotives - from diesel to electric for example, or even different types of steam engine so as to give more power for a particular section... So any interface should be flexible enough to cope with all these options (if you are going 9/10ths of the way you might as well go the whole way!)

So keeping above in mind, along with splitting and joining MUs, what is the reason for a player to want to choose this particular style of gameplay?

In real life splitting and joining MUs is generally done when there is a Y shaped route, with a shortage of train paths over the stem of the Y, but a desire to give both arms a direct service. Two contrasting ones that I know of are the West Highland Line, with long sections of single track, and the Brighton Main Line with an intensive commuter service. Sometimes instead of the two MU sections heading to different final destinations one section of the MU will just be detached at an intermediate station as the remainder of the route does not require as much capacity.

An extreme example I can think of for this are London Victoria - Hastings via Three Bridges and Eastbourne. Starting off with 3 4 coach MUs, at Three Bridges one splits off to serve stations in West Sussex, then at Eastbourne where the train reverses another 4 coach unit is left in Eastbourne to leave only one 4 coach MU to continue through to Hastings.

To model the above service currently you would have 4 lines - Victoria - Three Bridges, Three Bridges - West Sussex, Three Bridges - Eastbourne and Eastbourne - Hastings. Passengers would change at Eastbourne and/or Three Bridges to travel to their destination. There isn't really that much of a penalty for changing trains in simutrans so is it really that important for passengers to avoid leaving their seats? It may model real life slightly better but is this worth implementing quite a complicated interface? Are we crossing the line from transport simulator to virtual model railway? Same questions really apply for boats carrying vehicles.

Not entire code replaced but certainly lots of work!

[ӔO]

two more reasons why in real life splitting and joining is done

- steep mountain passes require helper engines. It wasn't entirely unusual to have helpers that only ran between the mountain passes.
* caveat is that, in simutrans, both standard and experimental, it's not really possible to simulate a good mountain pass.

- running a joined train through a single line reduces the total amount of traffic that must traverse the section, but with the same capacity.
* for simutrans, this would be beneficial, because of the way it handles signals.

[Fabio]

With freight, the player could save money having one loco pulling several convoys of waggons: while one is loaded the engine pulls the full one to destination (one loco and 14 waggons for 2 8-car convoys instead of 2 locos and 14 waggons).

Freighters sharing tracks with pax service could use a faster locos with higher running costs on the shared section (not to slow down pax trains) and slow locos for the freight only section (2 locos and 7 waggons instead of 2 locos and 14 waggons for 2 lines)

Ferries and shuttles would make you save on depots (expensive e.g. in Pak 128)

[jamespetts]

This has been considered, but it would, as Kieron points out, probably involve a very great amount of work, and is not currently a priority. If anyone else would like to code it, however, I should certainly consider adding it if it worked effectively.

[wlindley]

Especially with goods / freight, the chief hassle for the user will be in routing the Empties, especially because they tend to congregate like dirty laundry.  This is equally a hassle in the Real World.