ank, that is basically what I prototyped there.
The switch is connected to an under-floor wire (the panic line). A switch going HIGH anywhere along it's length will set it HIGH.
The dispenser is connected to an AND gate attached to both a pressure plate and the panic line
I then added a piston, to show how blast doors can be connected directly to the panic line. Unfortunately, it obscures the dispenser somewhat.
Making it "fail-deadly" (traps activate when panic line LOW) would require a lot of gates. With this, a simple AND per active trap works (passive traps eg. locks and blast doors don't need any triggering logic, a HIGH signal is enough) and a severed line is only a problem if there are not switches on both sides already pulled. Redundancy is as simple as laying the panic line out as a grid instead of a linear path.
Actually, simply shunting dirt/cobble/etc. into a few places in all corridors when the panic line goes HIGH would work great, as blasting every archway with stub cannons would be wasteful and time-consuming. Defenders could (assuming weak blocks) break and replace them to move around. The pistons don't even have to be sticky, making the trap only resetable by breaking blocks.
Also, all one-way doors need mouldings to be installed around them, preventing some 1337 HAXX0R from throwing a red torch or switch next to them.
Alternately, make them in "fail-deadly" style: doors installed sideways and held "open" (blocking passage) by redstone.