Remove ramp from z+1 layer

Question

EDIT See my comment below, this question is solved. HOWEVER, please do read, as the reason I use this (cart-only entrance), doesn't seem to work. That is, I have the construction as defined in the image below (except for a ramp on z-1, x2, y0, with a floor above it), but using D to show trader routes, still shows the path as inaccessible. Any thoughts on this?

Can anyone explain to me how I can create the following picture (as shown on the DF Wiki):

z = -1  z = 0
▓▓▓▓▓  ▓+++▓ 
▓+++▓  ▓+++▓  
▓▲▲▲▓  ▓▼▼▼▓  
▓+++▓  ▓+++▓  
▓▓▓▓▓  ▓+++▓  

I am having troubles removing all but the middle ramps in the Z -1 layer, without getting any dwarfs trapped.

What I currently have:

z = -1  z = 0
▓▓▓▓▓  ▓+++▓ 
▓+▲+▓  ▓+▼+▓  
▓▲▲▲▓  ▓▼▼▼▓  
▓+++▓  ▓+++▓  
▓▓▓▓▓  ▓+++▓  

What I tried (0,0 = top left):

• build floor at z0, x2, y1, remove floor, ramp still there
• Channel z-1, x2, y1, build floor at z0, x2, y0+1, remove floor at z0, x2, y0, floor at z0, x2, y1 now collapses on ramp, but ramp still there.

I'd like to do it within the confines of the above axises, and I can't use z1 due to being close to other caves.

The ramp is natural (well, by Channeling), not by building a ramp manually.

Answer 1

The problem you're running into is exactly what this design is supposed to make happen. The bottom 3x3 area is supposed to be inaccessible to anything except mystical wagons, so if your dwarf is down there, there's no way out. To fix it:

Go to your z-1 layer, remove the northern ramp, so the z-1 looks like this:

z = -1 
▓▓▓▓▓  
▓+++▓  
▓▲▲▲▓  
▓+++▓   
▓▓▓▓▓  

For any ramps that disappear during the building/deconstruction/remove-ramps section, rebuild them as a construction.

Now dig (using the dwarf who removed the ramp) an escape path, then wall it in behind you. I'd recommend heading out the north or south way, as if you go out directly east or west it might remove the left or right ramp.

For future attempts at this design, I'd work with these steps.

1. Given a north-south 3-wide corridor
2. Dig a channel (d-h) 3-wide across the corridor
3. When that's done: dig two 3-wide channels north and south of the first one
   • The delay is to avoid an accidental cave-in if the center of the 3x3 is the last thing standing
4. In the z-1 layer build a ramp (b-C-r) in the center of the 3x3 dug-out area below
5. Remove the 6 ramps (d-z) on north and south walls of the z-1 layer
6. You're done. Let your sacrificial dwarf starve and die down there
   • Or, dig him an escape route out (anywhere other than the center east/west walls) and build a wall behind him