reliability decay of old vehicles

[Wahazar]

Even if reliability decay can be changed via Action0, it is overridden if vehicle is old.
I expected, that such value should be increased proportionally to value defined by newgrf.

Current model of breakdowns is totally annoying and often is switched off, especially on multiplayer servers.
Not only annoying for user who is not logging frequently to set autoreplace of vehicles and see his railroad totally obstructed,
but also for the other users which are sharing infrastructure, for example if 'your' town covered in black smoke of competitor vehicles.

Unfortunately there is no way to fix it via newgrf.
One can decrease reliability decay speed, but it works only for new vehicles.

I want to keep vehicles old running (on decreased but not zeroed reliability), but increase running costs of old vehicles,
to keep original idea of forcing player to renew its fleet.
Is it possible to fix reliability decay speed of old vehicles? Second part is possible via newgrf code and works fine.

[Wahazar]

Seems that I messed something up, my thoughts were wrong. I checked vehicle.cpp code - reliability decay is just multiplied (shifted) for first 4 years after maximal vehicle age.
However decreasing reliability decay to 10 or even 5 does not resolve problem - still old vehicles loose its reliability too fast.
Value of 1..2 appear to be correct - old vehicle loose about 30% after half of the year - even if service is not scheduled, vehicle would visit depot after default 150 days.

Such low reliability decay work also fine for large maps.
You need to service vehicles after and of the run, not in a middle.
For example, with such low reliability decay, design of mixed freight/passenger railway line have common sense, because one can make overpassing using depots for slow trains, whereas fast trains can go straight.
With default reliability decay, fast trains must also use depots or will break and all overpassing design is not working correctly.

I will check this concept (decreased reliability decay + increased running costs) soon.

[Baldy's Boss]

I've hoped for an ability to keep old equipment running at a price for some time...good luck!

[Wahazar]

Above described method (decreased reliability decay balanced by increased running costs) was implemented in polroad set:
http://www.tt-forums.net/viewtopic.php?f=26&t=72694