Last week?s release of a draft environmental impact report on the Marin-Sonoma Narrows highway widening is seen as a major step in completing the $800 million project.
It also raises the question of just how extensive that widening should be, with the report examining two alternatives for improving the 16-mile stretch of highway between north Petaluma and south Novato.
Many of the improvements ? new intersections, frontage roads and extra lanes ? are identical under both options. But in the eight-mile ?Novato Narrows? corridor between Petaluma Boulevard South and Atherton Avenue, the report explores two different configurations.
The first alternative is the traditional third lane in each direction, a carpool lane added to each side of the highway in the median.
The second option is what?s called a ?reversible? carpool lane ? a single lane in the median, protected by new shoulders and barriers, that is open to southbound traffic in the mornings and northbound drivers in the afternoon.
While such a plan would allow flexibility for Caltrans in managing traffic flow in the Narrows, it is not without its drawbacks, the draft EIR states.
There would only be one entrance and exit point for drivers in the reversible lane ? no merging back and forth between lanes to pass a slow driver or exit onto a side road, such as San Antonio Road.
It would also require more manpower to open and close the reversible lane, and possibly electronic signs to let drivers know which direction the lane is flowing.
Finally, the lane wouldn?t do much for drivers headed in the opposite direction of peak traffic flow ? they would still be faced with a two-lane highway with no carpool lane in their direction, the report states.
The use of a reversible lane would create bottlenecks outside of the Novato Narrows, specifically along southbound Highway 101 in Petaluma in the afternoon and along northbound 101 in Novato.
The report also forecasts that future job growth in the North Bay could impact commute patterns, with more drivers headed northbound in the mornings. If the reversible lane was created and northbound morning traffic increased, the highway would likely have to be widened again to accommodate the new traffic, the report says.
The EIR also highlights specific improvements to be made in Petaluma to accommodate the widening project, including new freeway ramps and soundwalls.
In addition to a new northbound on-ramp being built behind the Petaluma Plaza shopping center at East Washington Street as part of a separate project, wider on-ramps with metering lights are planned.
The freeway?s rise over the railroad tracks in central Petaluma would also be rebuilt, in part to allow room for a Rainier Avenue cross-town extension underneath.
The longest soundwall in the Narrows project ? about one mile long ? would be built on the east side of Highway 101 between Lakeville Street and East Washington, to shield homes on Cedarwood Lane, Ramona Lane, Kresky Way and others nearby from freeway noise and light.
New interchanges would be built at Petaluma Boulevard South and San Antonio Road, along with a ?curve correction? to the highway at San Antonio.
Those projects are part of $200 million in Narrows work that will begin in 2010 before the widening of the entire highway, a plan put together by local, regional and state leaders earlier this year.
The draft EIR is available for review at the Petaluma Community Center and the Petaluma Library, and can be found online at www.dot.ca.gov/dist4/msn.
The public comment period on the EIR is open until Dec. 16. A public hearing will be held in Petaluma at 5:30 p.m. on Nov. 6 at the Sonoma-Marin Fairground?s Beverly C. Wilson Hall.
A second hearing will follow on Nov. 14 in Novato.
(Contact Corey Young at corey.young@arguscourier.com)
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