Iconic Placer County bridge is California’s tallest. See how inspectors make sure it’s safe

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Inspection work began this week using ultrasonic testing equipment to examine nearly 300 welds on California’s highest bridge to make sure the half-mile-long span remains safe for travelers in Placer County.

The Foresthill Bridge, just east of Interstate 80 near Auburn , is undergoing the tests to ensure its 282 welds are secure. A team of about 25 people, including Placer County employees, private consultants and Caltrans, will examine and double-check each weld on the steel cantilever bridge for quality and structural integrity.

County officials on Wednesday invited The Sacramento Bee and other news outlets to get an inside look at the inspection work that’s expected to continue for another six to nine months.

The Foresthill Bridge, which first opened to vehicle traffic in 1973, stands about 730 feet above the North Fork of the American River between Auburn and Foresthill. It’s the highest bridge in the state and the fourth-tallest in the nation.

Placer County Deputy Director of Public Works Matt Randall said Foresthill Bridge, like many others throughout the United States, is inspected at least once every two years; sometimes annually by Caltrans. The inspection work that started this week, mostly funded by the federal government, however, has never been done.

“There are things you can’t see with the naked eye,” Randall said.

The inspection work is being done with what’s called a “snooper truck” that is driven on the bridge. The truck has a large mechanical arm that reaches out over the side of the bridge, lowering inspectors to look at the structure underneath.

Ultrasonic testing is done by certified inspectors who use a single-element probe around welds to detect any flaws that might go unseen, according to the Federal Highway Administration . Randall said if any flaw is spotted, it’s likely repairs can be made on the spot during the project.

“That’s actually what we’re expecting, that any repairs will be simple,” Randall said.

If more extensive repairs are needed, Randall said additional work projects can be launched to complete the work.

“We want the bridge to be open and safe, not only for people driving between Auburn and Foresthill, but also for pedestrians who want to come out here,” Randall said. “The views are iconic.”

In December, authorities closed the Jennings Randolph Bridge over the Ohio River, connecting Ohio and West Virginia , because it had cracking welds that required four months to repair.

That bridge had similar welds and was built with the same T-1 steel as the Foresthill Bridge, which led to officials’ decision to test the bridge as preventative maintenance.

Randall has said the Federal Highway Administration issued a letter to Caltrans, saying that any bridge that used “butt-welds” constructed with T-1 steel would require ultrasonic testing. The Foresthill Bridge inspection work is part of a nationwide program to perform preventive maintenance for these types of bridges.

The project on the 51-year-old bridge, approved by the Placer County Board of Supervisors in late June, will cost $6.3 million, with 80% of the funding coming from the Federal Highway Bridge Program . The remaining 20% will be funded by California’s SB 1 Road Maintenance and Rehabilitation Program, a gas tax that was signed by Gov. Jerry Brown in 2017.

The inspection process is non-destructive, and the bridge remains safe and open during the inspection. Inspection work will be done weekdays, ending each afternoon before continuing the following morning.

Randall said they have no plans to conduct inspections on the bridge on the weekends, but it could be necessary if weather conditions or other issues create delays. While the inspection work is being done, authorities will close two lanes over the bridge, leaving two others open for vehicle traffic in both directions. One side of the pedestrian path over the bridge also will remain open.

The Foresthill Bridge has gained notoriety for the dangerous behavior of thrill-seekers. The Placer County Sheriff’s Office in 2015 began a crackdown on “girder hangers,” dozens of young people who illegally climbed the bridge’s narrow metal catwalk.

Despite the sheriff’s crackdown, people have continued to trespass and placed themselves in dangerous situations.

In 2017, a Sacramento woman was hospitalized after she fell about 60 feet while trying to get a selfie as she walked along the girders beneath the Foresthill Bridge. An Elk Grove woman in 2020 was rescued after falling off a girder. Last year, a 19-year-old man was being recorded on video swinging from the underside of the bridge , before his equipment failed and got stuck hanging about 30 feet underneath the catwalk.

“We ask that people let us do our work,” Randall said Wednesday, “and don’t do anything illegal or unsafe out here.”

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