Study says Napa Pipe homes project would add 1,600 cars to congested rush hour

By JILLIAN JONES
Register Staff Writer

The proposed development at Napa Pipe will put 1,600 new cars on the road during morning rush-hour traffic, according to a preliminary traffic study released Wednesday by Napa County officials.

During evening peak hours, 1,300 cars would drive to and from the south county site where developers are proposing 2,580 homes and a host of commercial and industrial activity.

Eleven intersections would be clogged if the project is built, 10 of which would be congested regardless of whether the Napa Pipe project is approved, according to the report. The nearby interchanges at Kaiser Road and Highway 221, and 221 at Streblow Drive would feel the greatest pain as a result of the development.

About half of the traffic from Napa Pipe would flow in and out of the city of Napa.

Because the estimates are based on a traditional traffic models, the figures may be high, according to Chris Mitchell, the San Francisco-based traffic consultant who unveiled the study Wednesday night. Final figures will be included in the environmental impact review of the project, scheduled for release later this year.

Mitchell explained that a more nuanced model would take into account additional project elements, such as density, design and proximity to public transit. While not yet considered mainstream, this innovative approach would project 15 percent fewer cars on the road than the traditional model and would show five fewer intersections feeling the crunch.                                    .

In the formal environmental review, however, consultants are going with the conservative projections “to make sure we’re not missing anything,” Mitchell said.

Napa County Planning Director Hillary Gitelman, who helped lead the special Planning Commission meeting Wednesday night at the Napa Pipe site, said it will be up to the public and to policy makers to decide which model is best.

Traffic consultants from Fehr & Peers, the firm preparing the traffic study, are also trying to predict what alternative uses of the Napa Pipe site would do to traffic.

The study shows that the most dramatic increase would occur if the site is developed industrially, a use for which it is currently zoned. If the project has access to rail — a possibility that has been proposed by developers — this would significantly reduce traffic on nearby roads.

The likelihood that rail may alleviate traffic at Napa Pipe remains an open question.

“The financial feasibility (of rail) is not something we’ve really gotten into,” Gitelman said. Instead, conservative figures assume that there is no access to rail at Napa Pipe.

Smaller versions of the Napa Pipe project would generate less traffic than the 2,580 homes currently proposed, according to the report.

While not presented Wednesday night, the final environmental report on the project will also analyze the potential effects of locating housing in other areas of the county instead the Napa Pipe site.

Gitelman said those calculations are “something we are struggling with right now. … It’s hard to say where those other sites are.”

Meanwhile, traffic consultants are putting together a list of measures designed to relieve traffic at intersections that would be congested if the project were to be built. These measures include the installation of several new traffic signals and lanes, a flyover at highways 29 and 221, and the reconfiguration of some nearby intersections.

The feasibility of these mitigation measures have not yet been studied, but will be analyzed in the environmental review, Mitchell said.

Some of these measures would be necessary without Napa Pipe, according to Mitchell. Gitelman said developers will negotiate with the county on estimating their fair share of the cost of implementing the mitigation measures.

Congested intersections, proposed solutions

First Street and Soscol Avenue: Add lane on First

Third Street/Silverado Trail/East Avenue/Coombsville Road: Reconstruct intersection

Highway 29 northbound/Imola Avenue: Install traffic signal

Imola at Soscol: Add lane on all approaches

Imola at Jefferson Street: Add lane on Jefferson

Highway 221 at Streblow Drive: Add lane on 221

Highway 221 at Kaiser Road: Add lane on 221

Soscol Ferry Road and Devlin Road: Reconfigure

Highway 12-29 at Highway 29-221: Southbound flyover

Highway 12/Airport Boulevard/Highway 29: Construct interchange

Highway 29 in American Canyon: Add lanes

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