We shouldn't stop at mere "footbridges". These crossings should all be constructed with both pedestrians and cyclists in mind, with dedicated "lanes" for each, and tying directly into the City's cycling network. Looking at that map... it seems obvious that Somerset and Donald Streets should have dedicated bike lanes built on them, to allow riders better access to the City core via an east-west cycling route. There are very few good routes for a cyclist to take to cross the Rideau River and the Canal.
The problem? Take a look at the Corkstown Bridge:
http://www.bing.com/maps/?v=2&cp=rk32m78psptr&scene=32821442&lvl=2&sty=b
Does that look like it integrates well into an east-west cycling network? Not to me. Just how do cyclists get across the U of O campus efficiently? What awkward ramps that just dump cyclists onto a pedestrian only campus access point.