BAscule bridge

History of Bascule/ Draw Bridge
A bridge over a waterway must allow boats or ships to cross under, usually by being tall enough to allow them to sail underneath it. Sometimes it is really hard to build a bridge high enough it may rise too steeply or block the view of an important landmark. In such cases, the bridge can be designed so it can be easily moved out of the way for the boats/ ships that are too large to sail under it.

The Robert Street Bridge is located in downtown St. Paul, Minnesota, where it carries Robert Street over the Mississippi River. The bridge links the downtown St. Paul business and commercial district at Kellogg Avenue with the city's west side neighborhood and the city of South St. Paul The dead load of the concrete roadway and the live loads are carried by the composite concrete and structural steel arch. The arch ribs have heavy steel cross-bracing below the roadway.

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• Grand Avenue Bridge in Chicago
• Washington Street Bridge in Chicago
• Blagoveshchensk Bridge in St.Petersburg
• Clearwater Memorial Causeway in Florida

credits

• http://www.drawbridgeahead.com/photosmain.html
• http://www.mnhs.org/places/nationalregister/bridges/nrrarsb/desc.php