Freeze/Thaw Weight Restrictions & Road Closures

What happens during a sudden freeze-thaw event on 

Whatcom County Roads?

Sudden Freeze Thaw Events

Some roads are constructed to handle freeze-thaw events, while others are prone to significant damage during such events. During the warming spell that follows a freeze, roads thaw out from the top down. Water becomes trapped between the road surface and the frozen ground below, causing the roadways to 'float' on a layer of water. As a result, heavy wheel loads can break through the pavement and destroy the road surface and subsurface, requiring costly repairs. To prevent this, some roads may be restricted for heavy wheel loads until the entire roadway thaws, allowing the water to drain out of the roadway.

Monitoring Freeze Thaw Events

Public Works monitors up to 15 frost sensors throughout the County to determine if a freeze-thaw event may occur. These sensors measure the soil temperature to a depth of 36 inches and are actively monitored from November 1 to April 1. If these sensors show that a freeze-thaw event is expected, the County Engineer may establish road restrictions to limit vehicle loads to protect the County’s roadways.

Stages of Road Restrictions

Stages of road restrictions are established according to County code, Chapter 12.06. The 1st stage is "Emergency," when there are no bus travel restrictions unless otherwise determined necessary by the County Engineer. When restrictions are elevated to "Severe Emergency" (2nd stage), the number of roads that buses are allowed to travel is reduced.

See the 'Related Documents' section below for a bus route map showing the roads that buses can travel on during "Severe Emergency" restrictions (2nd stage) and two lists of roads corresponding to the map.