Fundamental design problem #1 in airports is where the security is done. At present it is usually done as early as possible, just after the check-in desks. This leads to a range of problems; a huge sterile area, difficulties with connecting pasengers, duplicated catering and shops either side of the divide, need for double security checks at some airports, meeters and greeters no longer allowed down to the gate, etc, etc.

Move it right down to the gate, one at each gate, and do it as late as possible in the process, opening up for each flight either into a gate holding area or straight into the aircraft. Many of the difficulties then go away. It is not difficult to move security staff up and down between gates.

In case you have never seen this there are a couple of airports round the world where this is done. Kuala Lumpur is one, there are others. The difference is amazing.