A crowd of Tomales Bay area residents showed up at West Marin School Thursday to look over Caltrans plan to replace the Green Bridge in Point Reyes Station. The bridge carries an average of 3,000 vehicles on Highway 1 over Papermill Creek daily.

Caltrans would like to spend approximately $5.8 million to replace the 100-foot-long bridge, beginning in 2018 or 2019 and finishing three or four years later.

A team of Caltrans representatives were on hand Thursday to explain diagrams of four alternative designs for the replacement: a short, steel-truss bridge; a long, steel-truss bridge; a precast, concrete girder bridge; and a suspension bridge.

The underside of the Green Bridge.

“The current bridge was determined to be seismically deficient, and retrofitting the bridge was deemed infeasible due to limitations caused by the nature of the original structure,” Caltrans reported earlier. The bridge was built in 1929.

The alternative designs differ in: how the piers will affect the creek channel, affect neighboring properties, and alter the approaches to the bridge. They also differ in bridge height and in the thickness of the deck.

The short-steel-truss design is “very similar” to the present bridge, Caltrans says. ________________________________________________________________

The long-steel-truss design would be taller than the existing bridge.

It would have overhead bracing, which would put a limit on the height of vehicles that could use it.

Approximately 120 of the vehicles that now cross the bridge each day are trucks.

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Under this alternative, the bridge deck would be two feet thicker than it presently is. It would also cover more land and water, and this would have “moderate impacts to adjacent properties,” Caltrans noted. _______________________________________________________________

The suspension-cable design under consideration would have towers at each end, anchoring the cables supporting the bridge deck.

There would be “no piers” in the creek and there would be “no change to the current road alignment,” according to the state.

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A spot check of residents attending Thursday’s meeting found many people skeptical of the need to replace the bridge but resigned to it.

The hot-button issue was what will happen to traffic on Highway 1 and the intersecting levee road during the estimated 18 to 24 months of rebuilding. Caltrans has two alternative proposals for a temporary bridge, but each would be able to accommodate only one direction of traffic at a time.

Provision would be made for bicycle and pedestrian traffic, and a stoplight would be installed to regulate vehicle traffic. Vehicle delays would be “about five minutes,” the highway department predicted. The traffic jams on a summer weekend would be huge, numerous people warned.

A bridge too far?

Coming in for virtually no discussion was a smaller bridge about 60 yards north of the Green Bridge. This Highway 1 bridge was also built in 1929, but no mention was made of its condition.

Another bridge too far?

Also left unmentioned was a second small bridge, which is about 50 yards south of the Green Bridge near Marin Sun Farms. What’s the condition of its piers? I wasn’t about to wade around in the muck to find out.

A “draft environmental document will be made available for public review and comment in mid-2016,” according to Caltrans. “The final environmental document is expected to be issued by early 2017, and design completion will be in late 2018.

“Construction is expected to begin in three to four years and last approximately two to three years.”

People wanting to have their concerns considered in Caltrans’ planning can write the state at: <lagunitas_bridge@dot.ca.gov>.