SONOMA COUNTY (KPIX 5) – In the works for more than two decades, the Marin-Sonoma Narrows project to widen Highway 101 through the North Bay finally has light at the end of the tunnel.

Not since the construction of the new eastern span of the Bay Bridge has a road construction project in the Bay Area lasted as long as this one.

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The project been in the works for more than 20 years: 16 miles composing of 13 separate sections. Each complicated, each separately funded.

“We had to start one, finish it, start another one, and move along. Sort of like climbing a rope that’s slowly burning at the bottom,” said Caltrans spokesperson Jeff Weiss.

“Eventually you get to the top, but if you didn’t start climbing you would never have reached the top. And we’re almost there,” Weiss went on to say.

Construction on the Marin-Sonoma Narrows project to widen Highway 101 through the North Bay. (CBS)

Construction on the Marin-Sonoma Narrows project to widen Highway 101 through the North Bay. (CBS)

Marin has a small section near Novato to complete but this is the last big project making the corridor safer.

Sonoma County Supervisor David Rabbitt, who is also a commissioner on the Sonoma County Transportation Authority, told KPIX 5 about the old highway.

“When we first moved here, not that many years ago, we actually had a highway with dozens and dozens of crossings and driveways,” Rabbitt recalled. “And we had a lot of traffic and we had some horrific accidents.”

The final Sonoma section should be completed by 2022.

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Ashley Stephens said freeway construction has been a part of her whole life.

“Considering that I grew up here, I remember construction ever since I started driving,” Stephens said.

Stephens has a front row seat to the final chapter. Part of her backyard is right up against the freeway wall.

“We’ll be happy to have our yard to use back,” she said.

Rabbit says projects of this magnitude all have one thing in common.

“Unfortunately it takes longer than we like, usually costs more than we would like. But again, it’s built for generations to come,” he said.

Stephens remains optimistic. “Soon it’ll be over, maybe. We’ll see,” she said, laughing.

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The estimated cost of the entire project is nearly $1 billion.