Piles and Piers

< Construction Begins on the Detour | Building the New Bridge | Installing the Piles >

The piles had a long journey. They were shipped from the manufacturer in China to Vancouver, B.C., and from there were trucked to a subcontractor to be painted with a special anticorrosion coating to help protect the piles from salt water. After painting, they were then loaded onto the American Construction Company's barge in Tacoma, Washington, for delivery to the job site.

The steel piles that are being used for our bridge were originally designed to be 30 inches in diameter with a 3/4-inch wall thickness. During the engineering phases, it was determined by Geo-Technical analysis that our soil is extremely hard and requires additional wall thickness to drive the piles to the design depth. A determination was made to increase the wall thickness of the piles from 3/4 of an inch to 1 inch to ensure the piles could be driven into the hard Treasure Island soil. A secondary benefit: the expected life of the piles is increased. Because of the additional steel wall thickness, our bridge piles (which are exposed to salt water) may last for well over 120 years with proper care and maintenance.

Our new bridge will consist of 17 piers. Pier 1 is the west abutment on the mainland side and Pier 17 is the east abutment on the Island side. The remaining 15 piers (in the water) will each be supported by 3 piles and a concrete pile cap. There are a total of 45 piles with 15 pile caps supporting our bridge. Our old bridge has 137 piles.

< Construction Begins on the Detour | Building the New Bridge | Installing the Piles >