First Street detours

This map shows detours for westbound First Street and northbound and southbound California Boulevard. 

A new phase of the triple roundabout project will require major detours for thousands of motorists who use the First Street/California Boulevard intersection daily.

The “essential shutdown” of First at California will begin after Labor Day, with the goal of having the first of the new roundabouts operating by Christmas, said Eric Whan, the city of Napa’s deputy public works director.

“We understand there will be frustration by drivers. There will be inconveniences,” Whan said. Unfortunately, “this is a little bit of pain we have to go through.”

Major disruptions include:

— Westbound First Street traffic leaving downtown will be forced to detour onto side streets. Caltrans is recommending a right turn on Walnut Street, left at Clay Street, left at California and finally a right on First to go over Highway 29.

Motorists may choose to take Clay from Jefferson to California, or avoid the area altogether, taking Lincoln Avenue or Old Sonoma Road to get across the freeway, Whan said.

— Southbound California traffic will still be able to turn right onto westbound First, but it will not be able to continue south. Caltrans is recommending detouring left onto Clay, right on Seymour Street, then right at Third Street.

— Northbound California traffic won’t be able to connect to First. Motorists will have to turn right at Second, left at Seymour, then left at Clay to reconnect to California.

This next phase of the roundabout project, which is being coordinated by Caltrans, will be more disruptive to the 15,000 motorists who typically travel east-west daily than current construction, Whan said.

During the first phase that started June 19, traffic lanes were shifted on First and California, but the only closure was First’s northbound freeway on-ramp.

There were lengthy backups during the early days, but “people have figured it out,” Whan said. “Things have calmed down. Things are functioning.”

One reason traffic flows have improved is that many motorists are now avoiding this freeway crossing, he noted.

First at California is “ground zero” for roundabout construction, he said. “A lot of traffic goes through this intersection, but in order to get the roundabouts built, this is what you have to do.”

Both Caltrans and the city, who are partners in this project, will be monitoring traffic conditions to tweak the detours as necessary, Whan said. “If we have to add some flaggers, we may do that.” The date for the First Street closure later this month has not yet been announced.

Caltrans is working on an expedited schedule to finish all three roundabouts in 12 months, not the original 18. If workers can beat major rains this fall, the first of them at First should be working in December, Whan said.

When this roundabout opens, one-way traffic on First and Second will be flipped, with First now leading visitors into the heart of downtown.

The northbound freeway on-ramp, closed since mid-June, should re-open in the fall, Caltrans said in a news release.

John Ferons, a senior civil engineer with the city, said building roundabouts is a lot less disruptive, and less expensive, than if the city had opted to replace the two-lane First Street overpass, the conventional solution to increasing traffic capacity at the entry to downtown.

An overpass would have cost more than $60 million, compared to the $11.4 million contract to construct the roundabouts, he said.

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City Editor

Kevin has been city editor since September 2010. He joined the Register in 1973 as a reporter. He covered Napa City Hall and assorted other beats over the years. Kevin has been writing his Napa Journal column on Sundays since 1989.