Grand Conceptor Award – HDR Engineering, Inc. of St. Louis

Firm Name: HDR Engineering, Inc. of St. Louis

Project: Poplar Street Bridge Widening and Rehabilitation Project

Client: Missouri Department of Transportation

The MoDOT Poplar Street Bridge widening and rehabilitation project represents an engineering achievement that solved decades old problems in downtown St. Louis.  In lieu of a conventional widening, the 2165’ eastbound structure over the Mississippi River was slid 9’ to the south on its modified existing supports to widen the bridge for a critical 5th lane.  The eastbound and westbound superstructures were then connected together to transform the separate two girder bridges into a more redundant four girder structure.  The bridge slide was the 2nd longest ever in the United States and longest and heaviest for an existing bridge.  Also as part of the project, the existing overlay on the Poplar Street Bridge was replaced with an innovative 4” steel fiber reinforced lightweight concrete overlay mechanically connected to the steel deck plate via shear studs.  This new overlay not only provides a reliable low maintenance riding surface, but also increases the stiffness of the deck system making it less susceptible to fatigue cracking.