Go to nearest depot order does not work with double depots

[odalman]

According to the documentation, depots should be placed in pairs (or even larger combinations) on a line over non-diagonal track so that a train can enter one depot while another train is leaving the other depot.

It does not seem to be possible to combine depots (with Ctr+click, like stations and waypoints), so an order can not be to go to a pair (or larger combination) of depots. What can be done with orders is the the special "Go to nearest depot". To send a train to a constellation of depots, place waypoint before them, put the waypoint in the orders followed by the special "Go to nearest depot" order. Problem is that the train seems to pick one and wait while a train leaves it instead of going into the available depot. Note that the depots are equally near. The train should not wait.



Of course the train does not need to be ordered into the depot. It has to if it travels along the line. But trains should have a depot in the orders so that they will not try to find one on its own and possibly get lost. A workaround could be to let the last order be a particular depot (any, maybe not even connected) and just before that a conditional order that will always jump to the first order.

[odisseus]

The wiki, especially the parts about track design, is not official documentation. It is just a collection of advice written by players, and every single piece of it may be inaccurate, outdated or outright incorrect.

The nearest depot order should not be used for regular maintenance of trains, exactly because of the problems you mentioned. First of all, it makes doubled depots or depots on parallel sidelines completely useless, as the incoming trains will always choose the same depot. Secondly, the nearest depot may happen to be quite far from the route of the train, and the return route doesn't always exist.

I think that the algorithms of the game assume that there is at most one "nearest" depot at all times. Even if two depots are at equal distances from the train, like on your screenshot, one of them will be selected as the "nearest" one, and the other will be ignored.

In your case, the correct solution is forced service, perhaps with a waypoint to direct the trains to the point after which every path leads through a depot.

If you are concerned about trains straying off in search of maintenance, just make sure there are enough service opportunities along their route. A train will not seek a depot if it's not in need of service (unless it has an order to do so).

If you still want to have total control over times when your trains are serviced, try placing a depot order under a condition that is always false (such as load percentage < 0).

[odalman]

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