Here's one that's a little bit different - the destruction of a larger bridge and replacement by a more modest structure. The North Channel Bridge of the Seaway International Bridge in Cornwall, Ontario is being replaced. The high level structure will be demolished and replaced with a low level crossing. The cost of the project is $75 million and the new bridge will open for traffic in 2013 (entire project will be finished by 2016). A toll booth will be located on the canal lands.
Existing Bridge

by deanspic @ flickr
http://www.flickr.com/photos/deanspic/4745884674/

by deanspic @ flickr
http://www.flickr.com/photos/deanspic/2669050263/
The new project will be much more integrated into the Cornwall waterfront and will help faciliatate redevelopment of industrial properties on Brookdale Avenue, the arterial running along the approach to the bridge. The locks shown in the pictures were part of the Cornwall Canal, which became obsolete and was mostly flooded once the St. Lawrence Seaway was constructed. Large ships use the south channel on the other side of Cornwall Island and locks in New York to get around the Moses Saunders Power Dam.
pics from:
http://www.pontcornwallbridge.ca/eng
New Bridge
August 2012 construction