|
Dokken Engineering evaluated the seismic stability of Walnut Grove Bridge over the Sacramento River and prepared the plans, specifications and estimates. Built in 1952 by Sacramento County, this bridge carries a two-lane roadway that connects Walnut Grove and Grand Island. Since it is a historical landmark, any retrofit that affects the appearance was minimized.
|
The evaluation found the main bearings supporting the bascule and the vertical members of the tower truss to have insufficient strength to withstand a major seismic event. Dokken Engineering recommended retrofitting bearings by adding pier extensions and links, retrofitting the tower frame columns by adding new braces, and installing cast-in-steel-shell piles at both end of the bridge. To protect the slope in front of the abutments, rock slope protection will be used at both abutments. Dokken Engineering also worked with Sacramento County to finalize the PS&E package and respond to bidders questions.
|
