Chip seal on Highway 35

Last Friday, SVBC hosted a meeting with local advocates and Caltrans representatives to discuss the recent chip seal maintenance job on Highway 35. SVBC heard from a number of our members that the riding experience on Highway 35 had been significantly degraded as a result of the recent chip seal–and we responded.

Our invitation to Caltrans resulted in eight of their staff members meeting with us on site to discuss the issues that cyclists face on Highway 35, and how those have been affected by the recent resurfacing.

Part of this issue is that environmental regulations have compelled the agency to utilize a rubberized binder for the chip seal, and this is still undergoing experimentation. Caltrans is undertaking a study with UC Davis to determine how to improve the chip seal road condition for cyclists (see http://www.dot.ca.gov/dist05/projects/chip_seal/index.htm). Caltrans plans on testing the study's various options on Highway 1 in central California. One of SVBC's goals is to have Caltrans also study the road surfaces in Silicon Valley. Caltrans staff admitted that the success of the application of chip seal varies depending on weather and other environmental factors, so we'd like to see the study options demonstrated on Highway 35 in addition to Highway 1 down south.

Bicycle advocates had marked a number of trouble areas (emerging potholes) on Highway 35 in advance of the meeting. Caltrans maintenance representatives assured us that they would mitigate the issues, but that it may take several months due to funding constraints.

The chip seal used on Highway 35 was consistent with a specification that is now out of date–that of a 1/2″ aggregate treatment. The Caltrans District 4 Bicycle Advisory Committee commented, at our February meeting, on the specification for aggregate size, among other things. The current spec is for 3/8″, but many advocates feel that 5/16″ max aggregate is more appropriate for roadways that have high volumes of cyclists. The County of San Mateo uses 5/16″ max aggregate for their chip seal as a matter of routine.

In short, SVBC's goals in the matter are as follows:

  • Bring more of road resurfacing jobs to the District 4 Bicycle Advisory Committee for input.
  • Have Caltrans do part of its testing for the UC Davis road surface study on Highway 35 (they currently just have it planned for down south).
  • Fix the current issue areas (potholes, etc) on Highway 35.
  • In the future, after the results of UC Davis study are available, determine what other road surface mitigation we would like to see, such as resurfacing or re-rolling the affected stretch of Highway 35.

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