Horner & Shifrin designed a replacement structure for a 370-ft long bridge over the Big River in St. Francois County.  The existing bridge featured a 150-ft truss over the river and five concrete t-beam approach spans.  We streamlined design to cut the number of bents, resulting in a three span concrete bulb-tee replacement bridge.  The structure was widened to accommodate two 12-ft lanes of traffic with 2-ft shoulders.  Intermediate bents were founded on two 54” diameter drilled shafts which eliminated the need for a cofferdam.  The presence of a rock bluff required the use of a semi-integral abutment with steel h-piles set and concreted into drilled shafts in the rock.  The other abutment was integral and founded on steel h-piles.