H2R performed CEI services on the Atkins CEI Team for the construction of the Tampa Hillsborough Expressway Authority (THEA) Selmon Extension in Hillsborough County. H2R worked seamlessly with the owner and Contractor (Kiewit/AECOM) this design build performing Geotechnical and Construction Engineering and Inspection Services. H2R also provide geotechnical support to the CEI Team in addition to materials testing services on behalf of the Owner.
The Selmon Extension provides a direct connection the Lee Roy Selmon Expressway (which H2R provided CEI services when the firm was known as Williams Earth Sciences and Gannett Fleming), Dale Mabry Highway and the Gandy Bridge. The main project feature is a 1.6-mile elevated toll lane in the median of Gandy Blvd founded on non-redundant drilled shafts (dual 42-in diameter per cap and as deep as 180 feet). Due to limited space in the median, much of the construction effort occurred at night.
The elevation of the viaduct is 30 feet high to maintain sightlines for business along the lower Gandy and the signature bridge is both aesthetically pleasing and took into consideration public preferences, including artwork. The foundations, due to karst activity and a historic failure of a drilled shaft n the adjacent Crosstown Connector, were designed to carrying loads completely with skin friction.