I'm not doing this project so I'm not 100% sure if I'll be of much help in regards to the actual project, but I am in 1st year photography at uni...
I find it helps to start with what the word means; passageway can be interpreted as a good or bad thing I think. Good, because it connects people and places. Bad, because it could symbolise there was/still could be a reason for those people and places to be connected in a way that could at times be easily cut off.
Could be a good idea to look into the idea of movement, a passageway is a go between? Marcel Duchamp's painting - Nude Descending and Staircase, Alexey Titarenko's project City of Shadows is an interesting one that mostly shows people coming/going (would be easy and fun enough to recreate if you find a busy area and use a long exposure with a tripod), Henri Cartier-Bresson's image of a man using a make shift passageway from a ladder to aid him jumping over a puddle in France (could get a friend to help you stage something similar rather than doing what Bresson did and wait for the person to come along for 'the decisive moment')...
Could also look at Architectural photography and then follow that style to document passages/corridors/things linking each other in your area?
Hope this helps :-)