Chicago's Bridges

These are the four most popular bridge types in Chicago.

Bascule Trunnion

This bridge has a huge weight that counterbalances the bridge leaf at a pivot point (the trunnion). This makes opening and closing the bridge almost effortless.

Center Pier Swing Bridge

The bridge sits on a pier in the middle of the waterway and rotates to allow traffic to pass on each side. This bridge type was not maintained on the Chicago River, which is very narrow. But, a few remain on the Sanitary and Ship Canal.

Scherzer Rolling Lift Bridge

This bridge features a counterweight similar to the bascule trunnion. It rocks back and forth, almost like the legs of a rocking chair.

Vertical Lift Bridge

These bridges use counterweights to lift the bridge span into the air like an elevator.