The proposed Soscol Junction flyover at Highway 29 and Highway 221 southeast of the grape crusher statue might become the proposed Soscol Junction roundabouts instead.
It’s only an idea. A $40 million flyover joining southbound Highway 221 to southbound Highway 29 remains the preferred option to unsnarl the rush-hour backups caused by traffic signal red lights at this key intersection.
But Caltrans will allow the Napa Valley Transportation Authority and city of Napa to spend a few month exploring whether a double-roundabout design could handle the traffic.
“Once we do that analysis, we’re going to sit down with Caltrans and they’re going to take a look at it and see if that’s even a viable alternative,” Napa Deputy Public Works Director Eric Whan said.
The two roundabouts wouldn’t be on Highway 29. Highway 29 would simply pass through this area with no traffic signals to slow down vehicles, unlike today.
Rather, the roundabouts would be on either side of Highway 29 and serve as the onramps and offramps. They would also allow traffic to take a road passing under or above Highway 29 as a link between Highway 221 and Soscol Ferry Road.
For example, morning rush hour traffic pours from southbound Highway 221 onto southbound Highway 29 to head toward Fairfield, American Canyon and Vallejo. Vehicles make the transition using a left-turn lane and traffic signal.
The roundabouts solution would have no traffic signal. Highway 221 traffic would go through half of one roundabout, go under Highway 29, go through three-quarters of another roundabout and merge onto Highway 29.
A similar double-roundabouts design already exists in some California locations. Among them is a Truckee roundabout that opened at Interstate 80 and Highway 89 in late 2005.
Some critics of the flyover proposal say this towering traffic structure would be an unworthy gateway feature to the Napa Valley. Others say a flyover would be difficult for cyclists to use and would cut off the connection between Highway 221 and Soscol Ferry Road.
Such complaints helped spark the roundabouts idea.
“We think we will be able to reduce the number of concerns the community has if we have a proposal like this,” NVTA Executive Director Kate Miller told her board on Wednesday.
Napa County Bicycle Coalition Executive Director Patrick Band said the flyover would be unsafe for cyclists. Cyclists would be in an emergency lane prone to having glass, pebbles and other debris with speeding traffic to one side and a concrete barrier to the other.
Then there’s the roundabouts proposal. Vehicles in roundabouts drive more slowly than at intersections, and that’s safer for cyclists, Band said. But cyclists in a roundabout must deal with the vehicles that are entering and leaving.
“It’s really a mixed bag and it’s so context-specific, it’s hard to say anything in general,” Band said.
Cyclists today traveling between Napa and American Canyon face challenges, he said. Many view the Highway 221-to-Highway 29 route as being dangerous and the alternate route along Devlin Road lacks shoulders in sections.
“It’s certainly not traveled significantly right now, and a large part of that is it’s not perceived as safe,” Band said.
NTVA will spend about $40,000 studying the roundabouts option, with the city of Napa providing the engineering work. Napa is also looking at building roundabouts at California Drive and First Street, California and Second Street and at the five-way intersection at Silverado Trail and Third Street.
NVTA Planning Manager Danielle Schmitz said one factor to consider with the roundabout option is how to build it while still keeping traffic running on Highway 29 and the adjacent roads.
Whan said Caltrans developed the flyover proposal several years ago at a time when it didn’t always look at roundabouts as an option.
But times have changed. Caltrans in 2013 issued a directive that includes considering roundabouts as a way to control traffic at intersections on state highways.
Once Caltrans settles on a design for Soscol Junction, a big barrier must still be overcome before the project begins construction. The money must be found to build it.