A long-planned bike and pedestrian trail through Petaluma took another big step forward Thursday as a 142-foot arched steel bridge was maneuvered into place to span the Petaluma River.

The bridge, whose style mimics that of Balshaw Bridge over the Turning Basin downtown, plays a major role in connecting Petaluma's west side with the crosstown Lynch Creek Trail.

Midday Thursday, three 150-tall cranes hoisted the bridge in two equal sections over the river and into place on the already completed abutments along the riverbanks.

Crane operators cautiously maneuvered the segments over a large city sewer pipeline and a bank of AT&T electrical conduits that also span the river.

Called Copeland Crossing, the bridge at the north end of Water Street was the top priority for Petaluma Water Ways, a group of nonprofit and public agencies, property owners and individual volunteers working to increase recreational access to the river.

"This is a really big deal for cyclists and people who like to use the Lynch Creek Trail," said Susan Starbird, a volunteer with Petaluma Water Ways. "It's a great leap forward."

The bridge won't be usable until this summer because work, including a 10-foot-wide concrete deck walkway and ramps on either side, still needs to be finished. It is ADA-compliant with hand-rails nestled inside each of the two arches.

After each section was maneuvered into position, Ghilotti Construction workers bolted the halves together, then each end to the riverbank.

"It's amazing after all this work and then it's like four bolts and it's in," said Petaluma senior engineer Erica Ahmann Smithies, on hand Thursday to witness the installation.

The bridge cost $1.4 million, most of it from Measure M, a quarter-cent sales tax approved by county voters in 2004.

On the northeast side, the trail will continue along the river after the Army Corps of Engineers finishes a 30-foot section of flood-wall repair it has planned. On the downtown side, the trail will eventually connect to a riverside walkway along Water Street to the Washington Street Bridge.

The bridge is unpainted and is meant to have its rusty appearance. If it's tagged with graffiti, the damage can be sanded off, Ahmann Smithies said. It was prefabricated and trucked up from Southern California.

The bowstring-arch style is similar to that of Balshaw Bridge, the footbridge over the Turning Basin that links downtown to River Plaza.

"We were trying to get some continuity between this bridge and that one," said Gregg Grubin, a structural engineer with CSW/ST2, the designers. "We've been waiting a long time to get this in. It's going to look great."

You can reach Staff Writer Lori A. Carter at 762-7297 or lori.carter@pressdemocrat.com