Vine Trail Crossing Signals (copy)

Crews installed crossing signals at Wine Country and Solano avenues in May as part of work on the Napa Valley Vine Trail. Since then, motorists have reported greater traffic backups in the area. The city and Caltrans are trying to do a better job of synchronizing signals.

J.L. Sousa, Register file photo

Frustrated motorists may find driving in coming weeks a little more bearable along the Highway 29 traffic signal gauntlet of Salvador, Wine Country and Trower avenues.

Changes came earlier this year with a new Napa Valley Vine Trail segment sandwiched between Highway 29 and adjacent Solano Avenue. Trail users cross Salvador, Wine Country and Trower avenues and traffic lights were added to help them do so safely.

The result: drivers complained that the new signal timing regime caused them more rush-hour delays on both Highway 29 and Solano Avenue.

Noting that Caltrans controls the traffic signal timing along this highway stretch, city officials agreed to work with Caltrans and a traffic consultant to see if something could be done.

Caltrans discovered some of the vehicle detection loops in the pavement needed repairs, city Deputy Public Works Director Eric Whan said. Those loops are being fixed.

“That’s a step in the right direction,” Whan said this week.

Vehicle detection loops allow traffic signals to work on demand. Otherwise, signals can go through green light cycles even though no cars are waiting to pass through an intersection.

Such a situation could be observed along this Highway 29 section recently. An empty southbound Highway 29 left turn lane onto Trower Avenue had a green light, causing northbound Highway 29 traffic to sit at a red light for no apparent reason.

The detection loops need to be working for the traffic signals to function properly, Whan said.

The next step is trying out an adjusted timing pattern for the traffic signals based on simulations and traffic modeling. The goal is to create the optimum traffic flow and avoid undue delays for any one direction.

Whan said that this tryout could happen during December.

“We’re going to take a look at that and see what that does,” Whan said.

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This section of Highway 29 handles about 48,000 autos on an average day, according to Caltrans. Salvador, Wine Country and Trower avenues cross the highway within just over a half-mile. Six signals – three along Highway 29 and three along the Solano Avenue frontage road – must be in sync.

A wildcard to traffic signal timing is when the Napa Valley Wine Train passes by, forcing Trower, Salvador and Wine Country cross-traffic to sit longer than usual. The new Vine Trail crossings are yet another twist.

“It’s an extremely complicated timing,” Whan said. “That’s what we’re working through. We’re working through all the factors and working with Caltrans and seeing what we can do to make things work better.”

Napa Mayor Jill Techel acknowledged the problem at a recent Napa Valley Transportation Authority meeting. She said making crossings safer for the Vine Trail users had an unintended consequence.

The next few weeks could bring some relief, though to what degree remains to be seen.

“The big message is, ‘We get it,’” Whan said. “There’s an element of frustration (among drivers). We understand the importance of trying to fix the problem and trying to make it the best we can.”

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Napa County Reporter

Barry Eberling covers Napa County government, transportation, the environment and general assignments. He was worked for the Napa Valley Register since fall 2014 and previously worked 27 years for the Daily Republic of Fairfield. He is a graduate of UC Sa