|
Key Facts |
Bridge Name | Type | Road | Location | City | Crossing |
|
Monroe Street Bridge |
Bascule (Truss) |
Monroe Street |
Cook County, IL |
Chicago |
Chicago River South Branch |
|
Technical Facts |
|
Construction Date |
Structure Length | Roadway Width | Approach Spans | Navigational Vertical Clearance |
| 1919 | 271 Feet | 36 Feet | 3 Steel Stringers | 18.7 Feet |
This bridge was the first of this smooth-curved pony truss design for a movable bridge, and was the generation of trunnion bascule bridges that succeeded the bridge design seen on bridges such as Grand Avenue. I don't think they had quite figured out how to refine the ends of the bridge, however. The ends of this bridge have been modified heavilly and without respect to the original design, but it looks to me like the ends would have looked like the Grand Avenue Bridge, although the main central parts of the trusses feature the smooth curve seen in bridges like on Franklin Street. This bridge is also unique however because the engineers had to do some very special technical and mechanical design to get this bridge to fit near to Union Station which was under construction at the time. To save space, the counterweight, which is under the road on this type of bridge, was changed at one end only. At the west end, engineers used a smaller counterweight using heavier cast iron instead of concrete. The east end however had the standard concrete sized counterweight. There is a more technical description of this available in the HAER entry for this bridge.
