traffic highway 29 and Napa Junction Road American Canyon

Traffic piles up at the intersection of Highway 29 and Napa Junction Road in American Canyon, a problem that may only grow in coming years due to development projects near the highway.

Noel Brinkerhoff, Eagle

Commuting through south Napa County already is an unpleasant experience for drivers, due to congestion on Highway 29.

Guess what? It’s only going to get worse because of new projects in and just north of American Canyon.

Commercial development is humming south of the city of Napa, specifically off Airport Boulevard and Devlin Road.

Businesses aren’t the only ones flocking to the area.

The Napa Valley Transportation Authority is planning to relocate its bus maintenance yard to Sheehy Court, just off Devlin Road, from its present location in Napa.

Before it goes through with this move, NVTA conducted a traffic study to gauge what the automobile load will be like at its new location.

It did this because the agency won’t be the only new kid on the block, so to speak.

As Barry Eberling at the Napa Valley Register reported earlier this month, the Devlin/Airport Boulevard region may see the arrival of the Montalcino hotel and golf course, Napa Gateway Plaza phases one and two, Napa Bottling Center, Zapolski Rudd Winery, Gateway Winery, Napa Executive Management and Turnkey Technologies.

Citing the NVTA traffic analysis, Eberling wrote these projects individually won’t generate much traffic.

But collectively they will have a serious impact on Highway 29 at key intersections.

For example, the intersection of Highways 29 and 221 — Soscol Junction — has an evening rushhour traffic bottleneck causing motorists to wait an average of 67.8 seconds at the signal.

“Add all of the approved airport industrial area projects,” Eberling wrote, “and the delay will top 80 seconds,” according to the study.

The increase in congestion would be even worse at the unsignalized intersection of Devlin and Soscol Ferry roads, which many commuters use to avoid taking Highway 29.

There, morning commuters could see their wait of 37.5 seconds soar to an average of 80 seconds or more if the planned airport industrial area projects are built. The average evening commute waits already top 80 seconds.

At Highway 29 and Airport Boulevard/Highway 12, the morning rush-hour wait could go from 51.9 seconds to 70.7 seconds.

This intersection isn’t far from the northern reaches of American Canyon. In fact, Airport Boulevard/Highway 12’s meeting with Highway 29 is less than a mile north from the connection of Highway 29 and South Kelly Road.

Highway 29 and South Kelly Road is where traffic will be coming on and going off from two large commercial developments in American Canyon: Napa Logistics Park and the Napa Airport Corporate Center.

These projects were not part of the NVTA study. But it’s not difficult to imagine how Napa Logistics Park and the Napa Airport Corporate Center will adversely impact the traffic flow on Highway 29, both at South Kelly Road and to the north.

American Canyon’s traffic study for Napa Logistics Park concluded the project would generate 1,310 vehicles during peak morning commute time and 1,243 vehicles during the afternoon peak.

Those totals could drop to 780 in the morning and 704 in the afternoon, if the developer makes sure the tenants of Napa Logistics Park stagger their work shifts to distribute the traffic flows throughout the day.

But even if the second set of traffic projections is accurate for Napa Logistics Park, the traffic generated from Napa Airport Corporate Center will also be using the same interchange at Highway 29 and South Kelly Road.

The environmental impact report for Napa Airport Corporate Center said this project could produce 562 vehicle trips in the morning and 536 in the afternoon.

Then, there’s the biggest development project of them all — Watson Ranch — which would add 1,250 residential units and a new commercial center to American Canyon just east of Wal-Mart.

The EIR for Watson Ranch identified significant traffic impacts along Highway 29, not just in American Canyon, but at intersections north of the city, including those with Highways 12 and 221 and Soscol Ferry Road, and Highway 12 and Airport Boulevard.

A traffic study of Watson Ranch released by the city in March estimated more than 16,000 vehicle trips would arise daily if the project is fully built by 2030. Not all of these automobiles would head north on Highway 29, but a significant share would.

Add up all of this new traffic, from three large American Canyon projects plus the smaller ones near the airport, and you have to wonder what Highway 29 will look like in another decade during morning and afternoon commutes.

There are plans to improve traffic flows at key spots on the highway.

Eberling reported NVTA and Caltrans have talked about building either a flyover or a series of roundabouts at Soscol Junction. The key word here is “talked” — the project would cost $40 million. The money still must be raised.

Further south, American Canyon wants to expand Highway 29 from four lanes to six. Again, this project will be costly, and the funding is not yet secured.

Realistically, these highway improvements are years, if not a decade or more away. But many of the development projects will be built sooner than that, raising the specter of even greater gridlock in south county.