A problem to solve for the tough guys

The timetable should be written using rules in such a way that a train will not try to enter unless another train has been in to drop off tanks.

I had to abandon timetable on the train heading in the down direction and reverse it, then get the other train out of the sidings.

Unfortunately a third train then entered which resulted in me not being able to normalise the ground frame which I had to delete.

The timetable should be written using rules in such a way that a train will not try to enter unless another train has been in to drop off tanks.

Also, on closer examination (google maps!) there appears to be two siding roads at Dalston, one ~100m long the other ~200m. Are they both in use? The train length of 400m therefore is obviously a timetable bug to be fixed but equally the sim surely should not be allowing trains of this length to easily fit in the sidings.

" said:

The timetable should be written using rules in such a way that a train will not try to enter unless another train has been in to drop off tanks.

I don't understand what kind of timetable rules would apply for this. Also, I'm not sure if specific train rules would be effective in this case where the timetabled order of trains has become jumbled.

" said:

Also, on closer examination (google maps!) there appears to be two siding roads at Dalston, one ~100m long the other ~200m. Are they both in use? The train length of 400m therefore is obviously a timetable bug to be fixed but equally the sim surely should not be allowing trains of this length to easily fit in the sidings.

It seems (from google maps) only the southern road can be used for unloading, and of it only the fenced part which is about 120 m. However, this photo shows two trains at Dalston, one using the other siding.

" said:

" said:

The timetable should be written using rules in such a way that a train will not try to enter unless another train has been in to drop off tanks.

I don't understand what kind of timetable rules would apply for this. Also, I'm not sure if specific train rules would be effective in this case where the timetabled order of trains has become jumbled.

Such rules would be constructed as follows:

Let's denote the trains T1, T2, ..., where odd numbers arrive at the sidings and even numbers run out. Let's assume there must always be at most one train in the sidings, T1 forms T2, T3 forms T4 and so forth. So, the obvious rules would be (1) T[2*n] must enter xx minutes after T[2*n-1] has left. To avoid deadlock at the reversing point, you would, on top of that, add a Dalston calling point for odd trains and add a rule (2) T[2*n+1] must leave Dalston 0 minutes after T[2*n] passes Dalston. This could still get you into a deadlock if eg. T3 ran before T1, which means there's a third set of rules needed (3) T[2*n+1] must enter 0 minutes after T[2*n-1] has entered. This should be fairly solid, meaning it could only break if one of the trains was lost, or overtaken by a following train.

BTW, why do the down trains call at Dalston? If that is needed, please give them a NX stopping position so they don't block the Up line needlessly.

And a second thought, since the trains operate with one loco (at least it seems so from the photos), IMHO they should be running round somewhere (not in the sidings, that's impossible). Dalston station (that would lmit the length of the train to about 140 m)?

I don't do a lot of timetable writing so with that caveat- if you want to avoid T1, T3 and T5 all entering then use the MutEx rule and if they are type Q (run as required trains) then make them all have less than 100% probability of running, that way you may get none entering but never more than one.

In other words,
Trains can divide in the sidings but there will only ever be one locomotive because an incoming train is sometimes used to shunt tanks from one line to another or an incoming train might be split to enable it to fit.

Therefore the timetable must ensure that there will never be a situation where a train is trying to leave when another train is trying to enter.

And a second thought, since the trains operate with one loco (at least it seems so from the photos), IMHO they should be running round somewhere (not in the sidings, that's impossible). Dalston station (that would limit the length of the train to about 140 m)?

1. Because there are insufficient track circuits at Dalston, a train stopped at the station will always lock one of the ground frames so they can't be switched. This is really a showstopper as any run-round at Dalsotn needs to move both GFs.


2. And a slightly less important obstacle, the sim won't allow a train from Dalston South into the platform at Dalston. It will be held at an (imaginary) signal (can be passed at danger probably)

They do run round in the station, using one GF at a time. The length of trains is critical to avoid locking both GFs.