So, after great success with my 1 tile wide "bridge o' dodge to yer death", I'm curious...
How well will a 3-tile wide bridge filled with weapon traps (bCw) work out? Obviously, if they're dodging a trap in the middle, it won't, unless I load the traps with multiple weapons. And instead of a 6/8 chance of falling to their death there's now only a 3/8 chance if they're already along an edge.
In my last fort with the 1 tile wide bridge, no enemy made it more then 6 tiles across before falling to their death. So my current plan is to string a few 3x11 bridges between floating islands (with fortified kittens as bait to draw them onward). There's a 2x11, 8Z deep, pit on both sides of the 3x11 path sections.
[entrance] -- 3x11 path -- [kitten] -- 3x11 -- [kitten] -- 3x11 -- [kitten] -- 3x11 -- [fort]
If they fall during the first section, they come up the stairs at the first kitten (they advance a section). If they fall in the last 3 sections, they come back up the stairs at the middle kitten (which puts them back 1-3 sections). So I'll get them coming or going. If I don't like what is happening, I have dwarven atom smasher drawbridges covering any square that isn't trapped that can be cycled.
The major downside is that I need 3x as many traps and four sections of 3x11 pathway to ensure that they have good odds of falling off in a particular section. Plus I have to allow for weapon trap reset time. On the other hand, my entrance is now compatible with wagon traffic (even though there aren't any in .18).