Implementation of a Pile Load Test Program in the Design Phase: Marquette Interchange Project

Abstract

The $810 Million Marquette Interchange Project is a reconstruction of an interchange located in the heart of downtown Milwaukee, which connects 3 major interstates: I-43, I-94, and I-794. The Milwaukee Transportation Partners Geotechnical team for the Marquette Interchange Project was tasked with providing foundation design recommendations at 260 pier locations for 22 mainline and high level ramp bridges. The original interchange was supported by various 420-kN to 800-kN pipe and H-piles. However, for the new interchange the MTP Geotechnical Team recommended using soil set-up in order to achieve higher capacity piles up to 2225 kN with shorter pile lengths for a greater economy. The recommended foundation types were 1335-kN 324 mm, 1780-kN 356 mm, and 2225-kN 406 mm closed ended pipe piles. As a means to better define the potential cost savings to the project in foundation design, the MTP design team conducted a design phase pile load test program and has projected a project savings for the 2005 to 2008 construction to be as much as $11 Million less the difference between the pile load test program and the original geotechnical investigation cost. MTP determined from a value engineering analysis that if a similar foundation system of a highway project had at least a $2.5 Million construction fee, the project would likely receive a net benefit from performing a design phase pile load test program. This paper not only evaluates the advantages of performing pile load test during the design phase, as opposed to performing verification pile testing during the construction phase, but also addressed the process and implementation of the data obtained in the pile load test program into the final design and specifications.