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Crews chip seal a road.

King County Road Services - Chip sealing

What is chip seal?

Chip seal is one of the oldest and most successful road-resurfacing methods, designed to extend the life of a road's driving surface. The chip seal process involves applying a layer of asphalt emulsion and aggregate rock over the road. The process consists of liquid asphalt, immediately followed by rock chips (ranging in size from 3/8 to 1/2 of an inch).

The chip seal application helps restore the road’s skid resistance, smoothes irregularities and other damage, and prevents further deterioration of the road. Here's an example of what a chip sealed surface looks like.

Chip seal features

  • Prolongs the life of the road
  • Prevents further deterioration
  • Enhances skid resistance
  • Provides a moisture barrier
  • Corrects existing pavement damage
  • Saves money

How does the chip seal process work?

There are several steps in the chip seal process - follow them below. Please note that chip seal is only applied under ideal weather conditions.

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Why chip seal the roads?

The Road Services Division provides safe travel by maintaining more than 1,750 centerline miles of roadways and over 180 bridges in King County. We are committed to preventative maintenance and preservation of roadways in unincorporated King County.

With limited available funds, chip sealing is a short-term, cost-effective surface treatment solution that helps preserve the overall condition of the roads.

Due to the effects of weather, axle loads, average daily traffic and utility work, asphalt deteriorates over time. As part of our maintenance program, roads are chip sealed to provide added protection. A chip seal surface provides a coat that seals the road and enhances skid and weather resistance.

How does chip sealing affect motorists?

We appreciate your patience while the chip seal work is underway. Crews will make every attempt to work efficiently and effectively.

After a roadway has received a chip seal application, motorists are advised to obey the 20 mile-per-hour speed limit for a few days. Driving slowly ensures that the rock chips adhere to the roadway. Higher speeds can cause rock chips to fly and fresh asphalt to splatter. Street parking will be affected during the application process.

Contact information

If you have questions or concerns about chip sealing, please contact the King County Department of Transportation, Community Relations, at 206-684-1142.

Information from the Road Services Division's website is available to people with disabilities in alternate formats upon request by calling 206-263-6482 or 711 for the TTY relay service.

External link = External link
Related info
• Asphalt overlay
• Chip sealing
• Pothole repair
• King County 24/7 Road Helpline
• Concrete Road Preservation Pilot Project

Chip seal brochure
Chip aeal brochure
Download the chip seal brochure (169KB .pdf)

If your road is going to be chip sealed...

• Parking will be restricted on roads that will be chip sealed. "No parking" signs will be placed at each end of the road prior to work so you can move your vehicle from the street or shoulder. Parking restrictions will be removed as soon as we're done with the chip seal application, which typically occurs within a day.

• Access to your driveway may be disrupted for a few minutes but King County crews will work to minimize delays. The new surface can be driven on almost immediately, but slow speeds are required.

• High speeds can cause newly-applied rocks to fly and fresh asphalt to splatter. When driving on fresh chip seal keep your speed to under 20 mph.

• Bicyclists and motorcyclists should use extra caution due to loose rock.

• On the day of chip sealing, please keep your pets indoors or fenced in for their safety, and to avoid their tracking any chip seal residue into your home.

• Expect some loose rock immediately following the chip sealing. The roadway surface will improve over several weeks as the surface stabilizes, resulting in a stronger, more durable roadway.

• We ask for your patience as there are many factors involved with chip sealing, including good weather.