How Safe Are Sonoma County's Bridges?

One in nine California bridges are structurally deficient, including 15 percent of those in Sonoma County, according to a national report card on American infrastructure.

Commuters and travelers are thinking more about the possible risks of crossing of America's aging bridges following the collapse of the I-5 bridge in Washington State last week. 

In California, 4,178 out of 24,812 total bridges were deemed functionally obsolete according to the 2013 Report Card for America's Infrastructure, including 94 in Sonoma County. "Functionally obsolete" indicates the bridge's configuration fails to meet current demands for lane width, shoulder width or "doesn’t have enough vertical clearance for large trucks to pass under, causing repeat hits and damage to the bridge," according to transportation officials.

Another 106 of Sonoma County's 670 bridges were classified as structurally deficient, meaning a certain component needs repair or replacement. A bridge deemed structurally deficient is not necessarily in danger of collapse, according to transportation officials. There are 2,978 structurally deficient bridges in the state.

A May 2 database released by Caltrans lists all the bridges in the county and notes which ones have structural deficiencies or are considered obsolete. 

In Healdsburg, the bridge of concern is clearly the Memorial Bridge, where Healdsburg Ave. crosses over the Russian River at Veterans Memorial County Park. After several years of discussion, planning and public input, the current plan is for work to begin on the rehabilitation of the bridge – not its replacement or retrofit – to begin "sometime later this year,” according to Public Works Director Mike Kirn.

“We’re relying on CalTrans for funding, so we’ve got to play by their rules,” said Kirn. The two sticking points at present are securing right-of-way easements for the year-plus project, and final engineering plans for the rehabilitation itself.

An alternative means for pedestrians and bicyclists to avoid a 10-mile detour is also being actively pursued, with a shuttle of some sort currently being studied. The obvious alternative  - to temporarily detour foot traffic over the unused Railroad Bridge - has run into the figurative brick wall of the Northwestern Pacific Railroad Co., which says they plan to resume freight service to Healdsburg next year.

While the start date is uncertain, the duration of the Memorial Bridge project is expected to be 14-15 months, so a fall start would mean only one summer season would be impacted by the road’s closure, with completion by Spring 2015. More about the Memorial Bridge Project on the City of Healdsburg website.

Clarke Barrineau, spokesperson for the American Society of Engineers, which compiled the infrastructure report card, told the Huffington Post that while designations of "structurally deficient" and "functionally obsolete" sound scary, motorists aren't in imminent danger when they cross the spans. 

"If a bridge isn't safe to drive on, it'll be closed to traffic," Barrineau explained in this Huffington Post story. "If a bridge is rated as deficient, it just means that it has to be inspected on a much more regular basis due to risks coming from structural damage or regular wear and tear. Functionally obsolete bridges just aren't built to current standards."

It's important to note that the I-5 bridget that collapsed in Washington State was not structurally deficient. Rather, the bridge was functionally obsolete. Built in 1955, it was designed to be "fracture critical" meaning the entire structure can fail in the event of serious impact. There are about 18,000 similarly-designed spans in the U.S., including the Minneapolis I-35W bridge that spontaneously crumbled in 2007.