Coming soon: multi-start timetables and seeding

1) Trains entering which are governed by rule.

Suppose that the 00:00 start TT has Train A that leaves the sim at 04:30. Train B which is TT'd to enter at 05:00 has a rule that it must not enter until 30 minutes after train A leaves the area. If you select the 04:45 start TT, Train B will never enter as it is waiting for 30 minutes after the exit of Train A which has never run. If you delete the rule then in times of perturbation using the 00:00 start TT Train B may enter before Train A has left the area.

Maybe we need a new rule type to cover this situation using a time field.

So instead of Train B must enter 30 mins after Train A leaves the area, you could have Train A (which was train B in the earlier start) must enter 15 mins after 04:45.

Alternately the simplest fix would be to just remove the governing rule from the 04:45 start (in this case) and give the service an entry time

Having converted a couple of timetables to this new format, the process of duplicating the services to make the seed for another time, copies the decision as well.

On starting with the new start time, with the seeds enabled, any service that seeds with a decision will still choose one of the choices. There is no need for any new decisions.

Hopefully by midweek I will have a copy of the Sheffield 2019 TT converted to this format for trying out.

Sorry John lost my train of thought a little was thinking separate copies of TT not Multiseed (been a long day).

Maybe a new rule along the lines of Train A must not enter until x mins after [Seed Group] where you select the seed group time - in this case being 04:45.

As the original train B hasnt run in the 04:45 the original rule could be made to be ignored.

Alternately adding the seed group to each existing rule type could be used, where by rules in TT Start seed group would apply and by duplicating the rules that apply after the 04:45 would be read for that startup (see Mantis 25697)

Meld in post 119155 said:

Having converted a couple of timetables to this new format, the process of duplicating the services to make the seed for another time, copies the decision as well.

On starting with the new start time, with the seeds enabled, any service that seeds with a decision will still choose one of the choices. There is no need for any new decisions.

Hopefully by midweek I will have a copy of the Sheffield 2019 TT converted to this format for trying out.

Absolutely. But the problem isn't in duplicating the TT for Train A or Train B, it is further downstream. If you have a situation where a decision forces Train A or Train B to enter; they both leave the sim before the notional 04:45 and they form second workings Train X and Train Y which enter after 04:45 you would normally govern the entry of Train X or Train Y by having rules that Train X must enter after the exit of Train A and Train Y after the exit of Train B.

If you run the 04:45 start using those rules then neither Train X nor Train Y will enter as neither Train A nor Train B has entered. If you try and sort that by having a new Train X/Train Y decision and then run the 00:00 start you have the problem that the first decision may call Train A but if the second decision calls Train Y it will not enter as it is ruled not to enter until Train B has left the area. You can get round that by adding the same Train A/Train B decision into the TTs of Train X and Train Y. Train X has the choice Train A and Train Y has the choice Train B. That would sort the 04:45 start problem and make no difference when running the 00:00 start.

So the idea of tagging a X or Y decision to the 04:45 timetable should solve it completely - if you run 00:00, X or Y will govern A or B, but if you run 04:45 the appearance of A or B is governed by the decision (and tells you, if you are interested, whether X or Y is supposed to have run).

If you set a rule that Train B must enter 15 minutes after 04:45, that would cover the 04:45 seeding but what about the 00:00 start. If you leave in the rule about Train B entering 30 minutes after Train A leaves the area then Train B can't enter in the 04:45 start as Train A has not run so can't have left the area. On the other hand if you take out the 30-minute rule to make the 04:45 start work, leave in the must enter at 05:00 rule then run an 00:00 start where Train A is delayed and has not left the sim by 05:00 you would have Train B entering before Train A has left. The answer is to find some way of making some rules only applicable under certain circumstances. That is one for those who understand the core code to answer.

I think this can easily be rationalised. Any rules for “Train X must enter” should surely be irrelevant, and ignored, if the planned entry time is later than the seed, in all cases as normally we’d assume RT running in the default seed case and thus by extension to all seeds.

What would be nice is if the seed point was slightly variable to introduce inherent delay. Even better if it could be done automatically (ARS sims might be better at this!)

Thanks
Jamie

Not quite as simple as that. If you have trains due to enter which are parts of chains, the origin of which is a rule like "are alternatives" or "mutually exclusive" or a decision then just ignoring the "Train X must enter" rules would mean that all trains chained down from all of the parents would enter although only one should, tied back to whichever the rule or decision decided to enter before the seed time of the current run. If the parent trains had their entry governed by decision it is trivial to solve as you enter the same decision to the child trains as well. However, if the parent trains entered as a result of a rule you either have to go back and turn over all such trains to enter by decision rather than rule or you have to have some mechanism to tie a rule to a seed group so that the "Train X must enter" rule does not apply only if the relevant seed time has been selected and the code looks back to the rule governing the parent train to decide whether the child should run..

[quote=9pN1SEAp;post=119189
What would be nice is if the seed point was slightly variable to introduce inherent delay. Even better if it could be done automatically (ARS sims might be better at this!)

I'm not 100% convinced. For "normal" timetables, there are a set of alternatives/MutEx's that you would have in place. If you view an alternate seed time as just another timetable, there would be a set that applied just there. If the second seed were to depend on actions prior to seed point, the same (by reductio ad absurdem) would be true of the "normals". A rule depends either on something which hasn't yet happened (in which case, no change), or something which did (and then rules can be constructed as though the timetable just started at seed2). Provided that seeding can cope with alternative/mutex cases for new trains, I think all is well.

Thanks
Jamie

1) Train A enters by rule. Train X is due to enter after Train A leaves the area. However, Train X and Train Y are ruled as alternatives so there is only a 50% chance the Train X will run. Train Y cannot run as Train B has not left the area.
2) Train B enters by rule. Train Y is due to enter after Train B leaves the area. As before Trains X and Y are alternatives so ultimately you have a 50% chance of Train Y entering.

So unless there is a way to tag rules to seed times, making both parent and child trains have are alternative rules means that there is a 50% chance that no child train will run when the full TT is selected.