Road restrictions are a way to protect and preserve the taxpayer’s valuable investment in the County’s road system.This decision is made after taking several factors into consideration.

Example of road damage from heavy vehicle traffic during a freeze/thaw event. Courtesy of Mason Co. Public Works


WHY ARE RESTICTIONS PUT INTO PLACE? When the ground begins to thaw after a significant freeze it starts from the top down. The water has no where to go so it pools and builds up in the ground immediately below the pavement. The pavement is relatively thin and cannot support the weight of heavy vehicles and it soon begins to break up causing ruts and potholes.

HOW IS PAVEMENT DAMAGED BY A FREEZE/THAW EVENT? When the road base freezes below the asphalt surface, water is frozen in the road base. When thawing begins, the base thaws from the top down. Trapped water can’t drain through the frozen base below. The base, now full of water, can’t support heavy loads. Truck traffic deforms cracks or breaks up the asphalt road as water is pumped to the surface.

WHAT CAUSES THE PROBLEMS? The roads are restricted for a period of days to allow the water to absorb into the ground and the base of the road to restabilize. At first, the thawing ground is like a big bowl of pudding. Any weight on the road will just squish the substructure out of place. When this happens over and over, as on a highly travelled collector, the damage can be catastrophic, causing thousands, or even millions of dollars to mitigate. To repair the damage, we often have to dig down several feet to remove the compromised substructure and replace it with new. With over 1000 miles of road in the county, you can imagine how the costs of this could build up, causing the delay or abandonment of other projects.

HOW LONG WILL THE RESTRICTION LAST?  Road restrictions are in effect until the road base is thawed, and water has drained out of the road base. When this happens, the road base is stabilized. How long this process takes can vary greatly due to weather conditions.

IS THIS THE FIRST TIME YOU'VE DONE THIS? The last time Thurston County implemented county-wide restrictions was 10 years ago. It is not something we take lightly.

WHO MAKES THE DECISION? The calculations are made by Civil Engineers. We utilize weather reports and weather projections to calculate when restrictions should be placed and removed along with gathering field data on depth of freeze and thaw conditions. The proposal is then put before the Public Works Director and the Board of County Commissioners.

WHAT ABOUT MY FUEL DELIVERY FOR MY HOME HEATING? Delivery of life sustaining items such as propane or home fuel is still allowed under the restrictions. Companies delivering these and certain other perishable or critical products can continue deliveries, although they may have to carry reduced loads. If your vendor is telling you otherwise, you can ask them to call the county for clarification.

WHAT ABOUT TRASH PICKUP? Garbage pickup may be allowed, however trucks would not be able to run at full capacity, thereby requiring more trips. Because of this, carriers may opt to delay pickup. This decsion is up to the Waste contractor and not the County. Should you have questions about this, we refer you to your trash collection company.

WHAT COUNTY ROADS ARE AFFECTED? All roads in Thurston County that are not under the jurisdiction of another municipality, agency, or entity. We have produced a map that you can view HERE, with the included roads in PURPLE.


weight chart

WHERE CAN I GET MORE INFORMATION? You can call us at 360-867-2300.


ARE THERE STATE LAWS ABOUT THIS? Yes. The RCW (Revised Code of Washington)has statutes dealing with the implementation and fines for violation of the restriction. The Specific RCW granting this right is 46.44.080.

RCW 46.44.080 Local regulations — State highway regulations.--- Local authorities with respect to public highways under their jurisdiction may prohibit the operation thereon of motor trucks or other vehicles or may impose limits as to the weight thereof, or any other restrictions as may be deemed necessary, whenever any such public highway by reason of rain, snow, climatic or other conditions, will be seriously damaged or destroyed unless the operation of vehicles thereon be prohibited or restricted or the permissible weights thereof reduced: PROVIDED, That whenever a highway has been closed generally to vehicles or specified classes of vehicles, local authorities shall by general rule or by special permit authorize the operation thereon of school buses, emergency vehicles, and motor trucks transporting perishable commodities or commodities necessary for the health and welfare of local residents under such weight and speed restrictions as the local authorities deem necessary to protect the highway from undue damage: PROVIDED FURTHER, That the governing authorities of incorporated cities and towns shall not prohibit the use of any city street designated a part of the route of any primary state highway through any such incorporated city or town by vehicles or any class of vehicles or impose any restrictions or reductions in permissible weights unless such restriction, limitation, or prohibition, or reduction in permissible weights be first approved in writing by the department of transportation. The local authorities imposing any such restrictions or limitations, or prohibiting any use or reducing the permissible weights shall do so by proper ordinance or resolution and shall erect or cause to be erected and maintained signs designating the provisions of the ordinance or resolution in each end of the portion of any public highway affected thereby, and no such ordinance or resolution shall be effective unless and until such signs are erected and maintained. The department shall have the same authority as hereinabove granted to local authorities to prohibit or restrict the operation of vehicles upon state highways. The department shall give public notice of closure or restriction. The department may issue special permits for the operation of school buses and motor trucks transporting perishable commodities or commodities necessary for the health and welfare of local residents under specified weight and speed restrictions as may be necessary to protect any state highway from undue damage.