The California Transportation Commission on Thursday allocated $135.5 million for the Highway 101 Willits bypass project, setting the stage for construction on a project more than 50 years in the making.

"I'm having increasing optimism" it will materialize, said Willits Mayor Bruce Burton.

Opponents vowed to continue fighting the project, which runs through wetlands east of the city. "We have to decide what to do next," said David Drell of the Willits Environmental Center. "It's not over."

The 5.9 mile bypass is expected to be completed in 2016, said Caltrans spokesman Phil Frisbie. It would eliminate the only stoplights remaining on Highway 101 between San Francisco and Eureka.

Caltrans will begin seeking bids May 1. Land clearing could begin by winter, Frisbie said.

The cost of the project, including impact reports, permits, land purchases and mitigations for the loss of wetlands is expected to be about $210 million, he said.

The bypass has been on the drawing board for decades and many Willits residents were doubtful it would ever be built. Some remain unconvinced.

"I'll believe it when I start getting complaints from the community about the noise of the pile drivers," Burton said. He said there are news articles from the 1950s discussing the bypass as though it were imminent.

The bypass is aimed at reducing the traffic jams created when Highway 101 narrows to two lanes as it runs through Willits. Traffic stalls as cars and big rigs crawl through town. Congestion is worst in the high-travel summer months.

Funding, planning and environmental issues have stalled the project over the years. Most recently, a dearth of transportation funding most recently reduced the number of bypass lanes from four to two. Caltrans plans to eventually add additional lanes.

Despite the reduction in lanes, funding includes construction of high interchanges just north and south of the city.

Over the years, there has been opposition to the project, including from local environmentalists and business owners.

Drell said the project is unnecessary, oversized and backward. "It's a dinosaur," he said. He advocated what he called more progressive alternatives, including public transportation.

Some downtown business owners worry about losing customers if tourists end up skirting the city, said Willits Chamber of Commerce Executive Director Lynn Kennelly. But they also want something done about the traffic jams, she said.

Burton said there are things that can be done to create an atmosphere that nourishes business in the historic downtown district.

"I think it's going to give the city back its downtown," he said.