0007976: Minecarts suddenly 'inaccessible' while being guided

Dwarf Fortress Bug Tracker - Dwarf Fortress

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Date Submitted

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0007976

Dwarf Fortress

Dwarf Mode -- Transport/Hauling

public

2014-08-12 12:03

2015-03-29 07:56

Reporter

corvusikander

Assigned To

Priority

normal

Severity

minor

Reproducibility

sometimes

Status

new

Resolution

open

Platform

Linux

Arch Linux

OS Version

x86_64

Product Version

0.40.08

Target Version

Fixed in Version

Summary

0007976: Minecarts suddenly 'inaccessible' while being guided

Description

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.

Steps To Reproduce

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 [^]

Additional Information

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 [^]