Blast doors and bunker walls

[Unexpected]

This idea will probably not appeal to all of you, but for those of a turtling disposition I'm sure you've thought of something similar.

Now, I like to turtle when I play Rimworld. I like to find a big mountain and excavate an underground colony.
I may start with a settlement outside at first but I usually end up with a big bunker deep inside a mountain. Like a Vault from Fallout.
The problem is that the powered door is not much of a bunker door, it doesn't quite offer up the protection that I seek.
I want a Blast door, the kind you find in those secret military command centers hiding in the mountains (http://upload.wikimedia.org/wikipedia/commons/thumb/1/19/NORADBlast-Doors.jpg/1280px-NORADBlast-Doors.jpg).
And to complement that, a bunker wall. For added security, a max-security prison, a panic room or whatever you want to keep extra safe.

This is for those times when a massive raid breaks your killbox, blows up your turrets and you're utterly outgunned. You choose to abandon the outside and seek protection in the shelter and hope for the best. As most of your colonists make their way inside you toggle the door. It slowly rotates towards closed as your last colonist dives through the opening. A few raiders manage to get in before the door slams shut, but your defenders take care of them.
The door slams shut and the lights turn off as the outside power is disconnected. A few seconds later the backup batteries inside kick in and emergency lights come on. You hear faint sounds as the raiders are hitting the door, but you know that they can't break it down.
As the relief of being out of harm's way fades you start to wonder how long you'll be shut inside, if the power will last, if your food reserves are past their expiration dates, if that psycopathic new colonist will cope with the cabin fever and if you'll make it out alive.
Outside the raiders take out their frustration on whatever is left standing, before making off with your stored resources.



First, I'd like to make concrete a researchable item, project available from start.
Concrete should also, in my opinion, be made from ground up stone, not metal. The stonecutter table could be used to grind stone into cement, which is needed to make all things concrete.
Both the wall and the blast door need to be researched to be built.
Research progression:
1: Cement/concrete
2: Bunker wall
3: Blast door

The bunker wall should be made from cement and metal and look like a concrete wall. 2-3 times the amount of hp of a stone wall and immune to fire, small arms and melee.
The defensive bonus would be levied by a big resource cost. I'm thinking maybe 200 metal (rebar) and 400 cement per tile, or at least enough to make it a very expensive wall.
It should be so expensive that you should not be able to encase a big colony in this wall; it's for those areas where it really counts. Choke points, entrances etc.

I picture the door as being 1x3 tiles opening up to a 1 tile opening. It should be made from a lot of metal and concrete (a few thousand of each) and look like a massive metal door (1 tile) encased by concrete (on right and left  (C-D-C)) .
Unlike normal doors it doesn't open or close every time someone wants to walk through, it stays open for most of the time and you can toggle it to close. Closing should take some time (30 sec. to 1 minute maybe).
When open it conducts electricity through the opening, but when closed you break the connection and nothing gets through. The door should have a lot of hit points and be immune to small arms and melee combat (it isn't much of a blast door if you can kick it down). Mortar fire will do damage to it, as should the inferno cannon. Maybe at later stages the raiders can construct bunker busters outside the door and start wearing it down. The door should have a huge amount of hp to withstand this for a while.


Like I said in the start of the post, I know this way to play is not for everyone. It is something I'd like to see though, and I have a feeling I'm not the only one.
Any thoughts or comments?