Description: During construction of the new 5 mile long elevated section of the Leroy Selmon Crosstown Expressway it was discovered that the drilled shaft foundations that had been installed did not have sufficient capacity to carry the construction loads. This deficiency was not discovered until about half of the segmental bridge was constructed and a failure occurred at the leading edge of construction. Upon further geotechnical investigation it was determined that 27 of the bents that had already been built on needed remediation with additional drilled shaft foundations. 2-48” diameter sister shafts with depths of up to 90’ where installed at each deficient bent. The sister shafts had to be installed under the existing bridge with as little as 18’ of head room and in the 45’ median between the existing at grade lanes of the toll road. Due to BECK’s limited access drilling capabilities they were contracted to do the remediation foundations. Temporary casings had to be installed down to limestone then drilling fluid was used to stabilize the remainder of the excavation. A casing oscillator designed by BECK was used to advance the casing, then a low clearance drill rig designed and manufactured by BECK was used to excavate the foundations. After the excavation was completed the shafts where cleaned and SID tested. The reinforcing cages and CSL tubes had to be spliced over the excavation and then concrete was placed with a pump that is also designed and built by BECK.

General Contractor: PCL Civil Constructors Greg Fullington, Project Manager

Engineering and Inspection: Jacobs Engineering Scott Case, Project Engineer

Owner: Tampa-Hillsborough Expressway Authority