Cornerstone Structural Engineering Group provided structure design and construction administration services for the HBP funded seismic retrofit/rehabilitation of the historic Healdsburg Avenue Bridge over the Russian River.  In order to address concerns regarding the eligibility of the existing 1921 through-truss bridge for the National Register of Historic Places and a desire by the community to preserve the existing bridge, Cornerstone and the design team proposed several project concepts including a retrofit and rehabilitation of the existing bridge and construction of a new bridge while retaining the old bridge as a pedestrian walkway.  Cornerstone worked with Caltrans to determine funding eligibility of the proposed project concepts under the Federal HBP program. 

The Healdsburg City Council elected to retrofit and rehabilitate the existing bridge in place.  While the retrofitted bridge would remain functionally obsolete following rehabilitation, it was still able to receive approval of HBP funding because of its historic status.  Cornerstone incorporated several innovative features into the design including installation of lead-rubber base isolation bearings, outboard 8-foot diameter “super-bent” piles, and truss member strengthening and painting.  The project included obtaining regulatory approval and permits from agencies including SHPBO, USFW, CDFW, USACOE, NMFS, RWQCB, and the Sonoma County Permit and Resource Management Department.