Sonoma County Transportation & Land Use Coalition




A heritage road

Sonoma County has many miles of beautiful tree-lined rural roads. Most are quite narrow, with minimal or no paved shoulders and deep ditches close by.

Widening is seldom feasible. The County doesn't even have enough money to maintain them adequately. Even if money were not an obstacle, there would be resident opposition to widening because of expected increases in traffic volumes and speeds, as well as loss of the trees that line the roadways. Many residents don't even want potholes filled, preferring to take the bumps themselves than to encourage other drivers to drive fast.

While these roads are not inherently dangerous, they become so due to the often excessive vehicle speeds. Even the posted speeds are well beyond prudence. With the application of the 85th percentile rule, posted limits have been ratcheted up over the years as people have chosen to go ever faster, and the signs have been changed to reflect what people do.

But leaving roads to deteriorate is a poor option. Once they degrade to a critical point they must be rebuilt at great expense. In the long run, roads cost less if properly constructed and then maintained well.

The engineers understand this all too well, and one would expect them to want to do the job right if given the funds to do it. However, many of them believe that "doing it right" includes bringing the roads up to more modern geometric standards - widening lanes and shoulders, gentling the curves, lengthening sight lines. It is this part of the "standards" that brings them into conflict with the people that live nearby, because it results in higher speeds and loss of trees. To defend their choice, the engineers frequently fall back on the "necessity" of conforming to certain standards in order to obtain federal or state funds, or to avoid lawsuits over safety deficiencies. Yet recent studies have demonstrated that extra efforts to accommodate errant drivers have had negative effects on safety overall.

Faced with this reluctance of engineers to offer high construction quality while retaining historic geometrics, how can this conflict be resolved? There is a growing body of thought that those same geometrics look a lot like emerging practices of traffic calming. And the pioneering steps have already been taken to provide greater flexibility in design standards. Vermont, a state only 35% larger in population than Sonoma County, has many similarities: ruralism, beautiful rolling countryside, sprawl endangered, and narrow rural roads. It has established standards for local streets and roads that make use of the new flexibility in Federal Highway Administration (FHWA) guidelines.

With this as background, the SCTLC is proposing a System of Heritage Roads for Sonoma County. The concept is to maintain designated low volume rural roads in their historical configurations. The designation would be applied for by the local residents. In the application, they would accept certain (yet to be defined) speed standards, and fair sharing of the facilities by motorists, cyclists, pedestrians and other legitimate users of the road. In return, as funds become available, their Heritage Road would be improved without significantly changing geometrics, and user requirements would be enforced.

Although the source of funds to do this is currently unknown, it seems reasonable that a Countywide funding package would include a provision for Heritage Roads in the rural areas to balance off the transit and non-motorized facilities it would provide in urban areas.


The Vermont road standards are available at VTrans, the website of Vermont's Agency of Transportation. (Scroll down to 6.0 Local Roads and Streets.)

Clallam County, Washington has similar problems with its rural roads. Its Commissioners (supervisors) In 1999 its County Commissioners appointed citizen members to the Clallam County Rural Roads Design Standards Advisory Committee and charged it with two tasks:

Task 1. Formulate recommendations for appropriate levels of community involvement during road project development.

Task 2. Formulate recommendations for design standards used in road construction and reconstruction in rura lroad construction and reconstruction in rural areas.

The reports that came from the citizen effort could be a model for how to proceed in Sonoma County. They are available at the Safe Rural Roads website.

An excellent paper relating lane widths to safety was "Accident Relationships of Roadway Width on Low-Volume Roads" by Zegeer, Stewart, Council and Neuman.

Download Zegeer et al PDF file. (448 KB)

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