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0007976Dwarf FortressDwarf Mode -- Transport/Haulingpublic2014-08-12 12:032015-03-29 07:56
LinuxArch Linuxx86_64
0007976: Minecarts suddenly 'inaccessible' while being guided
When guiding a minecart, dwarves occasionally let go of the cart with a 'dwarf cancels Push Track Vehicle: Item inaccessible.' announcement.
I have only experienced this on ramps, which can be Fun for the dwarves in question when guiding uphill.
Most occasions seem to involve cats getting in the way, but not all cats get in the way all the time, and at least once I've seen it happen with no creatures present other than the dwarf guiding the cart.
There is also evidence of minecarts being let go (spilled contents by the corners of a spiral ramp) with no announcement.

The relevant world was generated (and the earlier incidences all occurred) in version 0.40.06, but the provided saves were made while running 0.40.08.

A world genned with 0.40.08 specifically to test this has reproduced the issue, and is the best place to see it with no animals involved.
I've uploaded a save where a minecart is just about to be guided up a long spiral ramp. Twice upon reloading this save, at around z=60 the dwarf has suddenly let go of the minecart as described above, and both times there has been a kitten in the same tile as the minecart, although an adult cat was passed further down with no problem.
I have also uploaded another save from just after the moment the event occurred on one of those reloads, in case there are some random numbers involved and it doesn't happen after a few attempts loading the first save.

first save: http://dffd.wimbli.com/file.php?id=9365 [^]
second save: http://dffd.wimbli.com/file.php?id=9368 [^]

There is also a save of a world genned in 0.40.08 specifically to explore this issue. There is a small spiral ramp, with a minecart moving up and down constantly, and 10 animals (plus a dwarf) trapped there by a forbidden door. The save is shortly after a collision has occurred, after multiple (lots) of movement without any issue. In this case, the minecart did not keep rolling to the bottom (although for me it did so shortly after loading the save, causing some more injuries).

I've also let the animals all out and let the dwarf carry on, and at least once the minecart has been 'inaccessible' with no other creature present.

I figured it would be useful to have a nice, high fps environment to reproduce the issue, but it's a lot harder to get as convenient saves as the original fort, hence uploading those anyway.

bugtest save: http://dffd.wimbli.com/file.php?id=9366 [^]
I have found previous mention (from DF2012) of this issue, or at least something similar, using the forum search but can't find a bug report (if there ever was one).
see this forum thread: http://www.bay12forums.com/smf/index.php?topic=111691.0 [^]
creature swap
related to 0008253new  Dwarf removing construction gets "creature swapped" onto construction tile, removes floor beneath his feet 
Issue History
2014-08-12 12:03corvusikanderNew Issue
2014-08-12 12:40corvusikanderIssue Monitored: corvusikander
2014-08-12 12:40corvusikanderIssue End Monitor: corvusikander
2014-08-12 13:19LociNote Added: 0028896
2015-03-26 12:35LociTag Attached: creature swap
2015-03-29 07:56FootkerchiefRelationship addedrelated to 0008253

2014-08-12 13:19   
Possibly another creature-swap bug: animal swaps with a dwarf while the minecart is on a ramp, minecart accelerates before the dwarf recovers, moving minecart is no longer "accessible" for guiding. If the swap happens when the minecart is not on a ramp, presumably the dwarf would flash a question mark then resume guiding the (still accessible) cart; have you seen any behavior like that?

It's also been suggested that a guiding dwarf who becomes too hungry, thirsty, or tired might abandon his cart, which, if it happens to be on a ramp, could lead to fun.