Snow and ice
Winter weather brings challenges for transportation in King County. The county’s resources to plow and sand roads have been significantly reduced since the region’s last major snow storm in 2010. Many roads in unincorporated King County that were plowed or sanded then are no longer primary snow routes. There is a greater chance you could become snowbound or disconnected from the road network.
- Find closed and restricted roads
- View traffic cameras in unincorporated King County
- Road Services preparing for snow and ice video
- Check your snow route and be ready!
- Learn why there are fewer snow routes
- Get emergency preparedness resources
- Find answers to frequently asked questions about snow & ice response
Check your snow route
Will your route be clear this winter?
Primary routes for plowing and sanding in a countywide snow and ice event
Why are there fewer snow routes?
King County crews respond to weather events that affect the bridges and roads of unincorporated areas – the network that keeps communities connected. In past years, the county was able to plow and sand critical snow routes. But the county is no longer funded to plow and sand as much as it used to.
Unfortunately, nearly three decades of annexations, declines in gas tax revenues, and the effects of voter initiatives have led to the chronic underfunding of the local bridge and road system. Fewer resources means fewer staff to perform work during inclement weather as well as year round, resulting in significantly reduced service levels for maintaining roads and bridges in unincorporated areas including plowing and sanding services. Key transportation routes for public safety will be plowed, however, in the past we were able to open secondary routes. The county used to plow and treat 30 percent of county-managed roads, but this year there are only resources to plow 15 percent of the county's 1,500 miles of roads.
Resources for emergency preparedness
The following websites provide emergency preparedness tips:
- Take Winter by Storm
- Office of Emergency Management preparedness
- Public Health emergency preparedness
- Metro Transit snow, ice and flood alerts
- Washington State Department of Health cold weather tips
- Federal Emergency Management Agency (FEMA) basic protective actions
- American Red Cross preparedness tips for seniors
The following links are to .pdf files from the Washington State Department of Health:
Frequently-asked questions about snow and ice response
Plowing public roads is dangerous work. Crews need to be proficient in avoiding a variety of hazards, including extreme weather conditions, out-of-control vehicles on slippery roads, abandoned vehicles, children playing near or in the road and steep terrain. With fewer resources, there are only half as many crew members available to provide snow response as the last time there was a major winter storm.
Second, there are a very limited number of individuals in the region who are licensed and trained to drive snowplows on county roads under dangerous conditions. The employees who do this work are intimately familiar with county road conditions, hazards, and snow routes, and are experienced in driving graders or 10-yard trucks with plows, sanders, and ice treatment equipment attached. The unpredictable nature of winter storms, the scarcity of licensed and trained workers, and the limited nature of this work combine to make hiring a seasonal workforce challenging.
Communities should not expect that roads other than primary snow routes will be plowed and sanded in a countywide snow and ice event. The county works with first responders to clear routes when there are extraordinary public safety issues, but otherwise the county is not likely to have the resources to get to additional roads. Travelers are advised to plan ahead before venturing out during a storm.
Anti-icing is the application of liquid chemicals to the road surface before the snow begins to fall. Anti-icing is used to help prevent ice from forming. Anti-icing chemicals can be applied to the road prior to a winter storm to help prevent a bond from forming and reduce the amount of time required to restore the roads to a clear, dry state.
De-icing is the process of applying liquid chemicals to the surface of the road after snow and ice has already compacted to it. The application of de-icing chemicals can have the effect of making roadway surfaces slick once they are applied. For this reason, King County crews utilize anti-icing (pretreatment) methods rather than de-icing chemicals.
Pre-wetting involves treating a salt and sand mixture with liquids before they are applied to the roadway. Pre-wetting these materials allows them to better stick to the icy road surface and helps to jump start the ice melting process.
Sodium Chloride (salt) is applied directly to the roadway surfaces once a snow and ice event begins. Salt is sometimes mixed with sand before it is applied to the road. Dry salt is most effective after the snow has accumulated about an inch and the temperature is 20 degrees Fahrenheit or higher. If the temperature is below 20 degrees, salt may not melt enough snow and ice to form a barrier between the pavement and the snow and could even produce more ice as melted snow refreezes. At these temperatures, a mixture of pre-wetted salt and sand are put down to break up ice and increase traction.
Calcium chloride is the chemical used to anti-ice and remove snow and ice from unincorporated King County roadways. Calcium Chloride is able to melt ice at lower temperatures than salt is.
King County may anti-ice when a snow or an ice storm is predicted, when roads are dry and when pavement temperatures are above 20 degrees Fahrenheit. The anticipated temperature and type of precipitation at the start of a storm will also help determine if anti-icing should be used.
Black ice, also known as “glare ice” or “clear ice,” is a thin coating of glazed ice on road. Black ice is not actually black. Instead, it is transparent, allowing you to see the asphalt road surface through it. Black ice often occurs along with wet roads, making it hard to see and especially hazardous for driving or walking.
Ice can form sooner on the decks of bridges and overpasses before it does on the roadway because air can circulate both above and below the surface of the elevated roadway, causing the pavement temperature to drop more rapidly. Ice can also form in shaded areas. Motorists should always use caution and expect slippery conditions when driving during winter weather.