Sonoma-Marin Area Rail Transit officials intend to buy a used drawbridge in Galveston, Texas, to replace the 109-year-old swing bridge over the Petaluma River.

Rather than launch a $20 million rehab of the aging structure at Haystack Landing, and then perhaps spending $30 million to replace it in 20 years, SMART says that for $20 million it can buy and install the used bridge and have it last 75 to 80 years.

"I was looking for a different solution than retrofitting it," said Farhad Mansourian, SMART's general manager.

SMART says it will have daily commute rail service on the line within four years.

The Texas bridge is on the BSFN Railway line linking the Texas mainland to Galveston Island. It was built in 1985 and is being replaced by a new vertical lift bridge to increase the channel width.

"It is a really solid bridge," said Bill Gamlen, SMART chief engineer. "We will have to do some mechanical upgrades, but it is a very stout bridge. The BNSF doesn't want to get rid of it, but the Coast Guard is driving the replacement."

It is called a bascule drawbridge, meaning it uses a counterweight to lift the "leaf," or rail bed, into an almost vertical position. It is on the historic vehicle causeway that was converted to a rail line.

Gamlen said the new bridge would open or close in about 90 seconds, instead of the 2? to 3 minutes needed for the swing bridge.

It also is long enough to allow the Petaluma River channel to be widened from 56 feet to 87 feet, and allow SMART trains to cross at higher speeds.

The bridge over the Petaluma River was built in 1903. It uses a 5-horsepower electric motor, fabric belts and bevel gears to pivot slowly on a turntable that is 10 feet in diameter.

"One of the problems with the swing bridge is the reliability," Gamlen said. "I have been out there and have seen it take three or four tries to get it closed."

SMART's long-range plan was to rebuild the bridge knowing it would need to be replaced within 20 years.

The 26-year-old bridge in Galveston can be purchased for $4.2 million and shipped to Petaluma by rail, then refurbished and reassembled on new supports for an additional $14 million to $16 million.

That would create a crossing good for about 80 years, district officials said.

Parts of old swing could be used in other areas on the SMART line, primarily at creek crossings and to replace existing wooden trestles.

"We have a consultant looking at where it might fit and what opportunities we might have," Gamlen said. "We would hate to spend money to dispose of it, and it is a historic element, we would like to keep it in the corridor."

Mansourian said SMART needs to move quickly because the Galveston bridge is being dismantled this week. The SMART board is being asked to waive the competitive bidding process to buy the bridge, and then seek bids from BSNF Railway Co. and Union Pacific Railroad to transport it by rail to Petaluma.

The board is meeting at 1:30 p.m. Wednesday at San Rafael City Hall.

You can reach Staff Writer Bob Norberg at 521-5206 or bob.norberg@