As announced last month, San Mateo County Public Works has finally found funding for the dangerous underpass at Alpine Road and Highway 280. Unfortunately, the design the County will move forward with was not SVBC's preferred option. This has created some worry in the cycling community that the redesign will not hold up to safety concerns.

Our voiced preference for redesigning the underpass had been drawing D-2 for the last 2 years (see drawings here Our members voiced support for both D-2 and D-3, although the majority preferred D-2.

For the last two years, we have worked diligently with the County of San Mateo and the Transportation Authority, with help and leadership from local members, to locate funding for the project. After several different rounds of being turned down for funding, recently the County was able to determine funding sources that could be used for the project. The big catch: the project has to be implemented before March.

Highway crossings are in Caltrans' right of way. This means that in order to restripe the underpass, the County needs an encroachment permit from Caltrans. Their efforts to get this permit for drawing D-2 led Caltrans to state that they would not give a permit for D-2 without an operational study on how it affected motor vehicle flow through the intersection. Caltrans doesn't move fast–meaning that if the operational study was performed, the March implementation deadline would be missed, and we would again be left with a project concept and no funding for actual design, much less implementation.

D-2 was not the design that we had asked for. However, after deliberation with numerous stakeholders, including our own Policy Advisory Committee, Bob Ward, and several bicyclists familiar with the situation, we decided that D-3 would certainly be much better than nothing–and furthermore, that it could be enhanced during the design phase to mitigate most of the concerns currently raised by some Portola Valley cyclists. D-3 very closely resembles the recommendation for a highway crossing treatment found in the VTA Bicycle Technical Guidelines, a manual that SVBC has officially endorsed.

As the County enters into the design phase for option D-3, we have made it clear that our support for this project is given only with the understanding that the County will work with SVBC and local advocates, including neighboring bicycle advisory committees, during design finalization, and that the following factors will be explored:

  • Make sure the area where cars merge to the right for 280 S is before the shadow line of the overpass (to enhance visibility of people on bikes in that area).
  • Add 1-2 ft cross-hatch buffers on either side of the bike lane to allow more comfortable riding for people on bikes, and so that motorists will be heavily discouraged from merging after the appropriate point. Also consider flexible stanchions to avoid cars merging across the bike lane after the appropriate point.
  • Add better lighting in the underpass area.
  • Reduce the minimum acceptable travel lane widths in the design to encourage slower vehicle speeds overall.
  • Treat conflict areas with green paint or slurry-seal for heightened visibility.

If you have ideas for further improvements to option D-3 (PDF, 24 KB), please let us know.