Hog's Back Bridge

The Hog's Back Bridge is an asymmetrical swing bridge over the Rideau Canal in Ottawa, Ontario. It carries 3 lanes of Hog's Back Road and a sidewalk. The bridge still swings in the summer when boats exceeding 9 feet (2.7 m) in height need to pass.

The bridge is hydraulically controlled. 2 wedge cylinders lock the bridge and raise the overhanging edge in place at road level. When the bridge is to be opened, from the control box up at bridge deck level, the bridge operator, who is with Parks Canada, lowers all 4 gates to block traffic from entering the bridge deck. The operator withdraws the 2 wedge cylinders which brings the bridge down a few inches and balanced onto a circular rail track. This movement also takes the weight of the bridge off the West side bridge bearings. Once the limit switches sense the wedge cylinders are fully retracted the operator can swing the bridge which is performed by 2 large hydraulic cylinders below the bridge on either side of the main bridge spindle. The hydraulic power unit has 2 main pumps which can be run independently or together, and one small backup pump to be run off a generator if need be.