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View from the Valley: 11/15/2018

Traffic on Highway 12 – Where are we headed?



By Kathy Pons, Valley of the Moon Alliance

Have you ever sat in your car waiting for a chance to get on the highway wondering, “Where did all these cars and trucks come from? Where are they going? How many more cars, trucks and vans can fit within our two-lane highway?”

Valley of The Moon Alliance (VOTMA) has wondered about this, too, especially as we see applications submitted through the county for projects that will add more traffic by their operations. Highway 12 is a state highway intended to operate at a Level of Service (LOS) “C.” According to Caltrans, LOS “C” on two-lane highways have a “greater than 50-65% Time-Spent-Following” and “greater than 45-50 mph Average Travel Speed.” That sounds familiar.

VOTMA is awaiting completion of a Sonoma Valley Traffic Study that the county has been working on for well over a year. It is supposed to look at the effects of visitors at events and provide updated, accurate traffic counts. Completion of this study seems to be put on hold; it is not clear when it will be finished and made available to the public. The only other model that is available now is a residence-based model at the Sonoma County Transit Authority (SCTA). It uses the parcel zoning to determine where people live and then have to go to work or school. It covers only Tuesday through Thursday trip movements, which is the traffic industry standard, but obviously not appropriate for our tourism-intensive economy.

This SCTA model is also used to forecast impacts of future development. It does factor in projects already approved but not built yet, if they are reported to SCTA by the cities and county approving them, but this reporting does not always routinely occur. VOTMA found that The Resort at Sonoma Country Inn was not included in the model and we are not sure how many more could be missing. This calls into question the reliability of Traffic Impact Studies that repeatedly estimate minimal impacts on local roads, including Highway 12. We need to develop some confidence that an accurate picture is being presented.

When a Traffic Impact Study is required with project applications, a traffic analysis is developed. It states assumptions made from the project description, looks at existing and future traffic volumes, determines the number of trips generated by the project and then determines whether there will be a “significant impact,” which most studies determine either doesn’t exist or can be mitigated.

Traffic Impact Studies do generally take traffic counts around the immediate vicinity of a project, but they are usually counted only on one mid-week day and one weekend day. They don’t track the whole day – just what are presumed to be the peak periods. The studies also are calculated using transportation industry general trip-generation guidelines that may not be reflective of the kinds of wine tasting concentration areas that exist in Sonoma County. Finally, the counts are not rechecked or trued up after the project begins operation to see if the estimated impacts bear any reasonable relationship to the actual traffic and visitor counts.

Each project is considered largely independent of others in the broader area and of changes in overall traffic patterns, so there is no uniform assessment of how all the projects approved or pending along a major corridor will realistically impact traffic flow.

There is a perspective in Sonoma County traffic planning that wine tasters don’t just go to one winery; they go to three or more wineries for tasting. Under this view, new tasting rooms are not generating much new traffic but simply tapping into traffic already going through on the highway. That may be understandable for industry-wide events where you pre-pay to go to a number of participating tasting rooms over a weekend. Absent more definitive evidence, it simply is not valid to assume that only one-third of traffic coming to a tasting room can be counted as its incremental “burden” on Highway 12. Two thoughts on this: 1) if visitors really are going to three or more tasting rooms within the seven to eight hour span they are open, I hope there is a designated driver; and, 2) we need clearer data on the actual numbers of cars and people that are visiting the valley.

The State of California is in the process of developing guidelines for an alternative to the residence-based congestion traffic model, instead using “Vehicle Miles Traveled” (VMT). This takes into account where the trips start (including outside a local area), and mileage to their destination. It looks at the whole trip to calculate green house gas emissions. This method takes into account the vehicles moving through from San Francisco to Santa Rosa, for example. The obvious point is that the VMT framework enables inclusion of tourist traffic in estimating local road impacts. VOTMA believes that the County should retain the congestion-based traffic impact approach and add in the VMT assessment in order to get a complete picture of the traffic effects of the growing wine industry event culture.

Back at the intersection waiting in your car, you may wonder where everyone is going. There are so many scenarios as to why that green Honda is driving by you. They might be going home or to work or to pick up the kids from school or going shopping. Fire victims may be commuting from temporary locations, along with all the trucks and workers needed to rebuild. It could be workers who have to commute a good distance because they can’t afford to live closer to their jobs. The traffic is not only visitors coming to taste wine, but it would be prudent to consider use permit activities accurately. The state of the highway is at stake.

If you have shared these pains and questions as a Highway 12 driver, we encourage you to check out www.dot.ca.gov/hq/tpp/sb743.html where you can read about SB743 Vehicle Miles Traveled and contact your state officials. We also encourage you to express your perspective to Supervisor Susan Gorin, Susan.Gorin@sonoma.county.gov, so she can have a clear understanding of District One input on this matter.

Have a wonderful Thanksgiving. We do have so much to be grateful for here in Valley of The Moon.

The Valley of the Moon Alliance was formed to promote the preservation, protection and maintenance of the agricultural character, natural resources and rural beauty of Sonoma Valley. We are committed to providing a forum for research, information, education and recommendations on projects that affect the environmental qualities of the valley communities.
Email: votma@kenwoodpress.com

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