So, I made a rapid cart deployment system, for when you need ridiculously small numbers of cats packed into a corridor NOW. Essentially, carts are driven into the top and each is caught by a door at a different point (note: there will be issues if you try to load carts faster than the delay time in the logic unit) then, at the pull of a single lever, all of the doors open, allowing all of the minecarts to fall, accelerating all the way, to the output track at the bottom. It's pretty dense, with one cart every four squares (plus a few for the edges, whatever you're using as a loading structure and 14 in the logic unit), and tiles in two dimensions (can be placed immediately next to each other and every four squares behind/below). As the logic units only move when something happens, there shouldn't be any significant lag except in loading (and in launching, but I don't think you'll notice it behind the lag from the carts themselves). It isn't combat tested yet, but it will be whenever I finish producing enough iron minecarts and weapons to fill them with to attract some goblins to come a-visiting.
Overall structure (side view):
RDWWRDWWRDWWRDWWRD
WRDWWRDWWRDWWRDWWR
WWRDWWRDWWRDWWRDWW
WWWRDWWRDWWRDWWRDW
RDWWRDWWRDWWRDWWRD
WRDWWRDWWRDWWRDWWR
WWRDWWRDWWRDWWRDWW
WWWRDWWRDWWRDWWRDW
RDWWRDWWRDWWRDWWRD
WRDWWRDWWRDWWRDWWR
WWRDWWRDWWRDWWRDWW
WWWRDWWRDWWRDWWRDW
TTTTTTTTTTTTTTTTTT
Legend (Above only):
R = ramp
D = door
W = wall
T = track
Basic unit:
HOLDING SYSTEM (side view):
TTTTTTiTR2WW
WWWWWWWWWR1W
WWWWWWWWWWRX
WWWWWWWWWWWR
CONTROL (top view):
WWWWWWWWWWWW
WATER->I1aXW
WATER->WWWWWW
WATER->IA2bXW
WATER->WWWWWW
WATER->IB3cXW
WWWWWWWWWWWWW
Legend (Basic Unit):
W = wall
R = ramp
T = track
A,B,... = door linked to plate a,b,... and also to release lever in holding system
I = door linked to plate i
1,2,... = bridge linked to plate a,b,...
X = door linked to release lever