San Mateo County will begin repairing cracked and rough pavement along a series of roads between Highways 1 and 35 ‒Skyline Boulevard‒ beginning Monday, August 29.
Ultimately, the project will improve road surfaces in San Mateo County, but will cause short-term delays and inconveniences for bicyclists. This is the 15th year of the county’s “chip seal” road maintenance program, a proven, cost-effective method that improves surfaces and causes less disruption to the traveling public than other treatments.
The project involves 50 miles of county-maintained roads. Beginning Monday, August 29, work will begin on Sunshine Valley Road, then move to Higgins Canyon Road and Purisima Creek Road.
While work in specific areas may vary, the project typically involves laying a layer of oil emulsion over the existing roadway and applying a layer of crushed rock over the emulsion, a process known as “chip sealing” because of the small rocks, or chips, placed on the surface.
After that, sweep the roads immediately after placing the chip seal, repeat a week later and again after 90 days.
“It is important that we continue to invest in these roads, as we have been doing for several years, to maintain the condition of these roads and minimize deterioration over time,” said Ann Stillman, director of the Department of Public Works.
“Chip seals have a lower impact to the public since vehicles can drive over them immediately after the rocks are placed and rolled. There is no curing time or lengthy road closures,” Stillman noted. “Another reason to use a chip seal is that it allows some of the work to be completed by in-house personnel, resulting in additional savings for the county.”
Pros and Cons
San Mateo County detailed in a statement that it understands chip seals have advantages and disadvantages. Cyclists have expressed concerns during a community input process that loose chips that can remain on the roadway can pose a safety hazard.
Public Works crews will monitor the work to determine if additional street sweeping would be beneficial.
Additionally, he said Public Works will install signs along San Mateo County roads scheduled for maintenance. The signs will alert motorists and bicyclists about the project so they can take extra care when using the roads.
The signs will also include the Department of Public Works' Highway Division number to request sweeping or report problems once the project begins: 650-363-4103.
All roads scheduled for work have previously received gravel seals.
On the “pro” side, Public Works is committed to extending pavement life and maintaining the county’s 316 miles of road network in the most cost-effective manner. The current approach for many coastal roads allows each road to receive a surface treatment—sealing—roughly every 5 to 7 years.
Gravel seals are a widely used, cost-effective treatment for rural and low-traffic roads, and the past 15 years of gravel seal projects have greatly improved the condition and reliability of the road network in the county's coast.
Next steps
The San Mateo County road maintenance project is scheduled to begin on Monday, August 29, 2022, and will take approximately four weeks to complete the 50 miles of roadway.
Project updates with a schedule of affected roads will be posted on the site. Project website.
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