Various improvements to operations will add a higher level of depth, progression and customisation.
Security
Instead of having small and large security objects it should be split up into basic equipment of metal detectors and bag scanners of low security but faster speed and advanced equipment like body scanners and ID checks which are slower but more secure. This would add more depth to a simple part of the game.
Gates
The sizes for gates are great but customisation and choices can be made by choosing from stairs and jetways. Stairs would be cheaper and lower satisfaction and jetways are more expensive and higher satisfaction. And option can be made to have a front and back stairway at the front door and back door to speed up boarding. This would allow more options creating choices like a stairway for 1 door, jetway for front door and stairway for the back and 2 jetways at the front for a larger aircraft.
Roads should be more realistic with options for rounded corners and one way roads. This last addition would make roads look better and force cars and trucks in certain directions making roads more realistic and helpful.
These improvements will be able to add depth and allow the player customise their airport in a cool and new way.