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Building a better bridge in Petaluma

More recently, the bridge project has been a lightning rod for conservationists who said that construction work trapped and killed protected birds.

A lawsuit forced Caltrans to change the methods it uses to keep birds out of the construction zone. Wildlife advocates say the new methods are safer for birds.

When the bridge project wraps up in two years, the new span will be wide enough to accommodate three lanes of traffic in each direction plus standard shoulders.

At 907 feet long with a 212-foot main span between pillars, it will be the longest bridge of its kind in the western United States.

It's what engineers call a precast, post-tension, spliced girder bridge, meaning the 10-foot-wide concrete girders were cast around steel cables that will be stretched to create tension once they are spliced together.

The arched girders, sleek fractured rib texturing and wave design along the pier caps and deck rails will make the bridge a landmark at Sonoma County's southern gateway, transportation officials say.

"This is a capstone project in the Marin-Sonoma Narrows," said Christopher Blunk, Caltrans senior construction engineer, referring to the 7-mile stretch of four-lane highway between Petaluma and northern Novato. "I think of this as Sonoma County's Bay Bridge."

The bridge sits between one highway section already widened from northern Petaluma to Windsor with a third lane for carpoolers, and another section stretching south from Petaluma to Novato, where widening remains in a funding limbo.

Besides the new Petaluma River Bridge, current construction in The Narrows is only to add frontage roads, improve interchanges and increase safety along the Highway 101 corridor. The work is not adding new lanes.

The highway construction has led to delays for commuters and factored in accidents, with curious motorists gawking at the activity.

"You see a lot of crashes from people staring at the construction. It really puts a damper on the commute," said Jen Jenson, a Windsor resident who drives over the Petaluma River Bridge each day on the way to work in Mill Valley.

CHP officers will help keep traffic flowing during the highly visible girder installation next week.

"Everything's going to be great when it's finally finished," Jenson said. "It will all be worth it."

But that could be a while, perhaps until the end of the decade.

When all of the current highway projects are finished in 2017, the bridge still will sit in the middle of a bottleneck as traffic merges from six to four lanes through The Narrows. The final widening project remains $225 million short, officials say.

The Sonoma County Transportation Authority has used money from Measure M, the quarter-cent local sales tax that voters approved in 2004, to attract regional, state and federal funds for the project. Authorities decided to do the preliminary work on The Narrows while continuing to look for the final funding pieces.

"As we have cobbled together numerous funding sources over the past decade or more, the (Transportation Authority's) approach has been to complete the most difficult and safety-related phases of work first," said Suzanne Smith, executive director of the agency. "These elements — frontage roads, interchanges, utility relocations — are now being completed and open the door to the widening work that comes next."

Smith said she doesn't foresee a funding source to complete the project until at least 2018. Construction could last two years after that, meaning the traffic bottleneck could persist until 2020.

Local funds from Measure M can't come to the rescue because they've all been committed, Smith said, and gas tax revenues, which pay for state and federal highway projects, are shrinking because of more fuel-efficient vehicles and inflation. Unlike most federal and state taxes, gas is taxed at a fixed cost per gallon, rather than a percentage of total sales.

The federal Highway Trust Fund, which has been tapped for some of the widening project, could be insolvent by late summer unless Congress acts, said Rep. Jared Huffman, D-San Rafael, whose North Coast district includes Petaluma.

Huffman has proposed replacing the gas tax with a carbon tax that would be assessed on producers of carbon-heavy fuels. The projected greater revenues would stabilize the trust fund and ensure the survival of one source of future highway widening money, he said.

"The problem is a gas tax that hasn't been modified since 1993," he said. "The revenue stream is woefully inadequate. If we fully funded the Highway Trust Fund, we could accelerate some of the (Highway 101) work."

Compounding the funding shortfall is the ban in Congress on earmarks, which dedicate funds for specific projects, Smith said.

"The federal transportation bill used to provide opportunity for projects like The Narrows in that we could receive earmarks to complete phases of work," Smith said. "In prior years this corridor received over $30 million in federal funds directly. Sadly, that opportunity is no longer available for good projects like this."

Once the wider Petaluma River Bridge is built, it won't be striped for six lanes until the rest of the highway is widened.

The Petaluma River Bridge is being built at the confluence of three major county transportation nodes, all of which are undergoing unprecedented transformation to improve road, rail and river traffic. This further complicates construction and requires close coordination with other agencies, said Kress, the Caltrans bridge engineer.

Besides the 43,000 cars that currently travel over the existing bridge each day, and barge and yacht traffic floating underneath the span, the Sonoma-Marin Area Rail Transit tracks also traverse the construction site.

Northwestern Pacific freight service currently uses the rail line, and, at the same time, SMART engineers are rebuilding the tracks to prepare for commuter train service to start in late 2016.

Later this year, 100 yards downstream from the Highway 101 bridge, SMART contractors will be replacing the aging swing-span Haystack Bridge with a drawbridge from Galveston, Texas.

Both new bridges will allow wider clearance for boat traffic, adding 33 feet at the rail bridge and 75 feet under the highway bridge. The highway bridge will maintain the current 70 feet of vertical clearance from the river.

The Coast Guard, which regulates traffic on the county's only commercial waterway, has required the widening of the bridges and the river. The spot where the bridges cross the river has been a major chokepoint for barge traffic.

After the two bridges are replaced, the Army Corps of Engineers will dredge the river, which has become clogged with silt after 11 years of without dredging. The Corps of Engineers recently received funding to plan the dredging project.

Petaluma tugboat and barge operator Jerico Products, which ships up to 1 million tons of sand, gravel and oyster shells per year on the river, has welcomed the wider passage.

"It will definitely be safer," said Christian Lind, Jerico general manager. "We will be able to get bigger barges up the river. It will be better for safety and efficiency."

The highway bridge will be built in stages in order to keep traffic flowing. So far, crews have built four concrete support piers, which are spaced farther apart than the current bridges' eight pillars.

Next week, the girders will arrive from Con-Fab California Corp. in Lathrop. The girders are so large that each one will be pulled by its own tractor-trailer.

A Manitowoc 2250 crane, a massive 300-ton machine, will lift 27 girders into place atop the pier caps in the median between the current bridge's twin spans.

The girders will actually sit on giant bearings that will allow the roadway to bend and flex on top of the columns during an earthquake, Kress said. Other safety features, including shear pipes, a deeper foundation and stronger columns, are designed to help the bridge withstand a 7.9-magnitude earthquake.

Caltrans will build a deck and a roadway on top of the girders in the median. This portion of the new bridge should be ready for traffic this summer.

Northbound traffic will shift onto the median and the old northbound bridge will be torn down, the chunks of concrete and steel placed in a barge to be recycled.

Then the new northbound bridge will be built and southbound traffic will shift onto the median. Finally, the southbound bridge will be demolished and rebuilt.

Caltrans plans show completion by 2016.

"It's absolutely challenging," Kress said. "We're building a bridge while there is traffic on the old bridge. We have to stage construction so that we can build a place for traffic to go."

Starting May 27, motorists can expect nighttime closures of the southbound bridge while the girders are lifted into place.

Sonoma County Supervisor David Rabbitt, an architect from Petaluma who sits on the Transportation Authority board, said he is excited to see the next phase of the bridge project.

"It is going to be a pain to put up with the construction, but the reward will be very worthwhile," he said. "We're building a bridge for the next generation and we should be proud of it."

You can reach Staff Writer Matt Brown at 521-5206 or matt.brown@pressdemocrat.com.