Community Corner
How Safe are Half Moon Bay Bridges?
Nearly 24 percent of bridges in San Mateo County are structurally deficient or functionally obsolete, experts say.
Written by Jennifer Squires and Jacob Bourne:
One in nine California bridges are structurally deficient, including 8 percent of those in San Mateo 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 92 in San Mateo 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 49 of San Mateo County's 598 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 some of the bridges in the county and notes which ones have structural deficiencies or are considered obsolete. In Half Moon Bay, one bridge is listed structurally deficient and one is functionally obsolete.
Structurally deficient bridges in Half Moon Bay:
- Main Street at Pilarcitos Creek, 0.25 miles south of 92
- Miramontes Street at Arroyo Leon Creek, 0.3 miles east of Main Street
"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.
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