Private car routing needs more active invalidation

[Vladki]

On stephenson simutrans game we have several occurences, where private cars end up looping a few tiles there and back, or can be even tricked into dead end. The trick is find a busy route junction, and delete one so that there still is an alternative (but a detour). The remaining route will come to standstill, and cars will start to pile up where the original route diverged. The wont continue, even if the alternative road is clear. You can try at stephensonsiemens - delete the road at (575,50) - (please do it offline). If you rebuild the old route, it will be used immediately again.

I tried that on less busy roads, and the cars seemed to adapt to new route much better.

Solution? - if the directions found by private car tell him to turn back, turn where no road is, or lead to dead end, the route for given destination should be immediately invalidated. Car should switch to old random mode (brownian motion)? Also any road deletion or change of oneway/twoway, should invalidate routes stored at that tile. Recalculation of route should not be immediate, as the roadworks may still be in progress.
(Or the car should be destroyed in an accident for obeying the navigation without applying common sense).

Funny places in stephenson-siemnes-game: (448,108), (553,98), (392, 119), (884, 475)

[Vladki]

After some investigation into stuck places, I found out roads that are almost unused (bypasses) even after two years after being built.
I suspect that the private car routing is not recalculated at all.

[Sirius]

I'd like to add that stored routes seem to take precedence over everything, thus mothballed road traps work again if placed on part or a route.
Further, cars can enter one-way roads in the wrong direction and pass unconnected roads as long as they are still adjacent.

[jamespetts]

Can I check whether this is still an issue following the latest private car routing changes?

[Sirius]

Further, cars can enter one-way roads in the wrong direction and pass unconnected roads as long as they are still adjacent.

That still persists, just after modifying roads with stored routes. Although routes will be updated rather quickly whenever that happens.

Not sure about mothballed traps, I'll try it out. In any case, such traps won't work for a long time as recalculated routes won't guide to mothballed roads.