I think the best way to make 1000 floors elevator is to have manual and automatic controls. For manual control nowadays we use its best as user perspective or to make range selector like we use in android mobile for number selection like for selecting calendar we just use that navigation interface for elevator. If some new member arrive so he/she will easily navigate elevator. And for automatic process I think the fastest and best way is to use face recognition system similar to Window Hello. Before entering to lift the camera above the elevator will scan the face of persons that he/she is the owner, employee or someone else related to the plot or floor. That way restricted floor will be secure and no one can access except the owner / employee / worker (or others new person for limited period).

You don’t as there are too many floors. Elevator should travel in one direction only. Traditional call box used to open doors on required floors only.

Firstly I am assuming that there won’t be any budget problem. Ok there are two options and we have to test which one is the user preferred yes I mean user preferred, with real user testing. a)It has to be touch screen (sleek user interface with LCD screen). The interface can be like calculator (not exactly like calculator just the key part) were user can punch the key in and the output will be seen on LCD touch screen. b)Second option > the idea inspiration comes from Apple, yes iPhone were you slide and select the fore (just like how we set date or time in iPhone) Yes of course both the interface has to be tested, when I say tested; tested with real users. Note: There has to be some big/or small LCD displaying on each floor (not sure about each floor) to display were the lift is going to stop. Both inside and outside the lift. Putting LCD outside the lift in a proper location will be easy but not inside. It has to be placed in L shape were the door open. on top of the door ( \ like this) so each one can see the LCD no matter where they are standing or tall or short one ;) To see more interview question please visit my blog. https://nadimkhan.wordpress.com/2012/08/24/ux-user-experience-interview-questions/