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0008439Dwarf FortressDwarf Mode -- Tradepublic2014-10-17 13:432014-11-04 18:57
0008439: Caravan wagons can use unusable ramps
Normally, ramps can only be traversed when they are braced against a wall and the direction of movement is toward said wall when moving up (or away from the wall when moving downward) - any ramp which does not satisfy this is labeled as "Unusable".

However, caravan wagons are still capable of traversing such ramps, while pack animals cannot.
This behavior dates back to at least, possibly earlier.

Back in version (the last 2D version), there was no logic to require ramp support during movement, and normal units were able to traverse such "unusable" ramps just fine in both directions (though wagons could not traverse ramp tiles at all); perhaps wagons were given the ability to traverse ramps before normal units were updated to require properly supported ramps, and their movement code still remains separate (as evidenced by the fact that the "turbo speed" debug flag* does not affect them).

(* of the 12 debug flags that still exist in the current version: disabling Pause, disabling Strange Moods [which dates back to before ARTIFACTS:NO], affecting combat in some what, disabling wildlife invasions, disabling hunger/thirst/drowsiness, showing ambushers, speeding up mining, disabling thoughts, disabling Berserk insanity, and speeding up everything; please do not feel compelled to remove these, since the DFHack community finds them quite useful)
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related to 0011029confirmed lethosor wagons stuck in walls after riding down the ramps 
Issue History
2014-10-17 13:43QuietustNew Issue
2014-10-26 11:47LociNote Added: 0030740
2014-10-26 12:38QuietustNote Added: 0030741
2014-10-26 12:55QuietustNote Edited: 0030741bug_revision_view_page.php?bugnote_id=0030741#r12118
2014-10-26 13:18LociNote Added: 0030742
2014-11-04 18:57FootkerchiefAssigned To => Footkerchief
2014-11-04 18:57FootkerchiefStatusnew => confirmed
2019-02-15 09:51lethosorRelationship addedrelated to 0011029

2014-10-26 11:47   
If you actually observed this behavior in v0.40.13 I would like to hear your test procedure.

This was a well-known bug in older versions, but it was fixed early in the v0.40 branch. Testing v0.40.13 specifically:

a) unusable ramps are shown as vertically unnavigable on the 'D'epot Access view
b) wagons are capable of moving through (not up) an unusable ramp tile
c) wagons will not travel up an unusable ramp, choosing a longer detour around it
d) if wagons in a depot could only exit the map via an unusable ramp, they will remain in the depot, refusing to use the unusable ramp

In short, wagons appear to handle unusable ramps just like every other creature.
2014-10-26 12:38   
(edited on: 2014-10-26 12:55)
I actually did test it in version 0.40.13 just now, using the following steps:

1. build a pillar a few blocks away from a hill edge
2. build a 5x5 floor over it
3. build a trade depot on the platform
4. remove all access to the platform - Shift+D now reports the depot as Inaccessible, and caravan wagons bypass the site
5. construct a row of 3 (unusable) ramps next to the platform - Shift+D now reports the depot as Accessible, and caravan wagons are able to climb up it (but pack animals cannot)

2014-10-26 13:18   
Interesting. My problem was apparently that I neglected to build floors behind the ramps, which prevented the wagons from moving into the ramp tile and using the ramp. Adding those floors made the unusable ramps usable by wagons.