Purdon Crossing Bridge slated for substantial work
March 11, 2013
Nevada County's road system contains about 80 bridges or box culverts in various states of repair.
Recently, the county government put out to bid a project to repaint and rehabilitate one of the more iconic bridges that serves as a recreational focal point for many residents and visitors — Purdon Crossing Bridge.
The bridge, a rare surviving example of a pin-connected Pratt Half-Through Truss, which was built in 1889, has a number of functional and aesthetic problems, according to the latest bridge inspection performed by the California Department of Transportation in 2011.
The timber railing and rail posts are loose with sagging connecting points while the entire apparatus exhibits heavy distress, the inspection states. Many important bolstering elements of the truss are bent, loosed or warped.
“It will basically look like a large plastic sandwich.That’s what’s driving the cost.”
— Steve Castleberry, Nevada County Director of Public Works
Regarding the paint job, "moderate corrosion was observed throughout all the truss elements," the inspection states. "It is unknown if the truss was ever painted. If the truss was painted in the past, the paint system has failed."
Thus, the county has issued a request for proposals for a construction firm to replace certain structural elements of the bridge while painting the entire structure black, said Nevada County Director of Public Works Steve Castleberry.
The engineering estimate approaches a half-million dollars, according to the bid documents.
Castleberry said much of the expense can be attributed to the difficulties of the project, the foremost of which is the necessary sandblasting that must occur. Because certain parts of the bridge were covered in lead paint, the project manager must encase the entire bridge in plastic, thereby preventing any flakes from falling into the river, Castleberry said.
"It will basically look like a large plastic sandwich," Castleberry said. "That's what's driving the cost."
Other factors such as the remote location and difficult access exist, Castleberry said.
Chairman of the Board of Supervisors Hank Weston said Purdon Bridge is old and the county has considered outright replacement, but the project has repeatedly proved cost prohibitive.
"We are talking millions of dollars and a massive construction project, Weston said. "To get a brand new bridge you would have to go through CEQA studies and the entire process."
Weston, who served as Grass Valley Fire Department Chief from 1997 to 2006, said both Purdon and Edwards Crossing bridges are liabilities to the fire service.
"As long as I've been (in this community), fire trucks can't cross those bridges," Weston said.
The weight limit on Purdon Bridge is four tons, according to Caltrans.
While several firefighting trucks and firefighters are stationed at Station 84 — a mere seven miles away from Purdon Bridge — if a fire broke out just across the South Yuba River, firefighters would have to travel the 18-mile circuitous route via Highway 49 and Tyler Foote Road to battle the blaze, Weston said.
"When it comes to fire in this area, it is a matter of when, not if," Weston added.
The improvements proposed as part of the Purdon Bridge Painting and Rehabilitation project will not make the bridge accessible to fire vehicles but will attempt to prevent further corrosion and shore up stability, Castleberry said.
Funding for the project is funneled through the state by the federal government via the State Exchange Funds and Highway Bridge Program Funds and will have no impact on the county general fund, according to a staff report prepared by Castleberry.
In 2012, nonprofit organization SaveCaliforniaStreets.org inventoried about 11,800 bridges in California that were owned or administered by local agencies such as counties or cities.
Of those bridges, about 1,500 are 80 years or older with the largest number of bridges (2,300) falling in the 40- to 49-year-old range. A total of 1,887 bridges were deemed to be structurally deficient (16 percent), and 1,796 bridges are functionally obsolete (15 percent), according to the study.
The study further estimates that $4.3 billion will be expended over the next 10 years with $2.6 billion dedicated to actual replacement.
Currently, it is estimated that about $300 million a year is available for bridge repairs and replacement, but legislation and an emphasis on infrastructure projects could skew that number upwards, the study states.
The study concludes that "given existing funding levels, California's local streets and roads can be expected to deteriorate rapidly within the next 10 years."
Caltrans performs tests
Caltrans has come under intense scrutiny from local officials recently due to an $840,000 project overrun on the Highway 49 renovation near the intersection of La Barr Meadows Road.
"If any of us at the city or county level, if we were to blow something like this, we would get dragged down the street," Fouyer said. "The Caltrans folks won't feel that pain as much as we do."
Criticism directed toward the agency is not relegated to Nevada County, as the Sacramento Bee reported this week the agency was fudging data regarding the structural integrity of major bridges throughout the state.
The Bee article prompted a large-scale and comprehensive investigation (known as the GamDat Report) into Caltrans activities that found 11 significant instances of "data that may indicate potential inaccurate or inconsistent reported test results."
"These cases represent irregularities in test data collected over a four-year period from 2004 to 2008," the report states.
The Bee reported that Duane Wiles, a technician who confessed to falsifying data, retained unrestricted access to data archives long after his fraud was discovered.
The GamDat Report did not explicitly mention Wiles, or his supervisor Bill Liebich, who was fired from his position as the head of the Caltrans testing branch in 2011 after being accused of an alleged theft of federal construction materials and related abuse of pay rules regarding his employees.
Liebich has refuted the allegations and appealed his firing, the Bee reported.
While Nevada County administers all bridges on the county transportation network, Caltrans is responsible for testing the bridges and providing data to county public works, Castleberry said.
To contact Staff Writer Matthew Renda, email email@example.com or call 530-477-4239.
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