DBA is working with Parsons Transportation Group and Kiewit-Clyde (a joint venture of Kiewit and W.W. Clyde & Co.) on part of the I-15 Express Link project in Salt Lake City, Utah. DBA is working only on one bridge within the project: the Beck Street Bridge replacement. An existing 6-lane bridge will be replaced and widened to 8 or more lanes utilizing two bridge structures. The southbound bridge is being constructed first adjacent to the existing bridge. Once completed and traffic has been shifted, the existing bridge will be demolished and the new northbound structure will be built.
The abutments are going to be supported by 12.75” diameter, closed-end, concrete-filled pipe piles. The interior bents will be supported by 9.2’ diameter drilled shafts, heavily reinforced for seismic loads. The new approach embankments will include MSE walls and have deep soil mixing under the area adjacent to the abutment to mitigate ground vibration issues. The approach embankments were designed by others.
In addition to liquefaction issues, the bridge spans several railroad tracks that include Union Pacific lines and one commuter rail line. There are also several pipelines in and around the planned foundation locations. The pipeline service an adjacent oil refinery.
I (Robert) was on site recently to observe the excavation of the first shaft. Malcom Drilling Company, Inc. is performing the shaft excavations using a temporary segmental casing advance ahead of the excavation with an oscillator. This method is well suited for the soil conditions that consist of layers of sand, clay, silt, and gravel from both the Great Salt Lake when hit was higher in the past, as well as glacial outwash and alluvial deposits from the Wasatch Mountains adjacent to the site.
I have embedded a slide show and some video below.
You can see all of our project photos on Picasa Web Albums.
You can see all of our project videos on YouTube.