A solution appears to be the one used by El Al, which is the same as is used to control access to many high security buildings and installations within insecure buildings, such as data processing and communications areas.
Double doors. Each is reinforced and the first must be closed and locked before the second can be opened. This creates what is known as a 'man trap' between the two and can be used to isolate low risk individuals, although in a/c that is less likely!
If the attacker breaches the first door, he will certainly have drawn attention to himself.
I understand that El Al also have toilet and food areas on their side of the double doors.
[ 09 October 2001: Message edited by: PAXboy ]