[ChrisD]

In another thread I read this:

Quote

Each train uses it's path to clear it's own route ahead. It checks the data if that route is clear and if so, it will 'reserve' that route. If not - the route is reserved by another train - it will wait and will keep checking until the other train is gone.

That is, that a train in an activity, reserves the sceduled route, all the way to the end, if possible. An end that may lay 3 hours into the future???

I also read that special code is used to resolve the gridlocks that arise from this way of doing things.

Would someone "in the know" tell me why this solution has been chosen and not one that resembles reality?

F.eks.: I read about problems with a shunting task that was difficult to get right because another train had locked the mainline.

Now, If each train clears, say 4 sections ahead at all times, the shunting train would reserve the station tracks, unless another train was within 4 sections, in which case, the shunting could not start until the approaching train has passed.
As long as the shunting train is occupying the tracks, both signals guarding the entrance to the station would be red stopping any approaching trains, that might show up.

In my opinion, this would make things a bit more realistic.

However, before asking any more silly questions, I would really like to know, why the present solution has been chosen.

ChrisD

[James Ross]

I think that the trains do reserve only a few sections down the line (based on the signal data) but router will be able to confirm.

[roeter]

The maximum distance trains reserve ahead is based on the following criteria :

• if in SIGNAL mode : as set by the SignalNumClearAhead variable in the signal definition (sigcfg.dat file).
  Assuming these values have been set correct, the route ahead is cleared as far as needed to avoid unnecessary restrictive aspects - and no further.
  
• if in NODE mode : max. of 5000 meter or the max. distance covered in 2 mins. based on the maximum allowed speed, whichever is the longest.

In MANUAL mode, the distance is limited to 3000m.

In EXPLORER mode, it's a bit like normal mode but not really relevant as there are no other trains in explorer mode.

The 'special processing' as mentioned is the deadlock processing, which will check for all trains against all other trains for common sections in opposite directions, and will set 'traps' to avoid deadlock situations. This is required as the signalling itself cannot sufficiently safeguard against such deadlocks. Not because trains reserve too far ahead - but because on single line sections with intermediate signals, they do not reserve far enough - the number of sections cleared may not reach to the other end. Automatic reservation to the next switch would not help - there might be switches in between the passing loops, e.g. leading to dead-end sidings.
The deadlock processing has some limitations : it does not extend beyond reversal or waiting points.
When a train activates a reversal or waiting point, it asseses the deadlock situations for the next part of the path.

Deadlock processing is switched off for player train in MANUAL mode because of the possible changes in route-selection and direction. This can lead to problems when shunting on single line sections, and we hope to extend the manual mode some time in the future to include some sort of deadlock prevention.

As there are no other trains in Explorer mode, deadlock processing is not active in that mode.

I hope this makes it a bit more clear.

Regards,

Rob Roeterdink

[ChrisD]

Thank You Rob.

That cleared the tings up a bit. :)

ChrisD