Alberta Frost Laws, Seasonal Load Weight and Speed Restrictions – 2025

2025 FROST LAWS UPDATE.

The Alberta Ministry of Transportation offers a subscription service on its website to drivers who wish to stay up-to-date with road ban orders and seasonal weight changes. According to the website, seasonal weights for heavy haul are set according to the following schedule:

Spring is weather-dependent and subject to thaw depth reading. It begins at the same time as Period 1 (weather dependent and subject to thaw readings of at least 25 c)m.

Seasonal weights

Seasonal weights for heavy haul are set according to the following schedule:

• Spring: weather dependant, subject to thaw depth readings of at least 25 cm, and begins at the same time as Period 1 weights for service rigs
• Post-Thaw: June 16 (may begin one week earlier or one week later)
• Summer: July 1
• Fall: September 1
• Winter: weather-dependent, subject to frost depth readings of 75 cm or more.

Seasonal weights for service rigs are set according to the following schedule:

• Period 1: weather dependant, subject to thaw depth readings of at least 25 cm, and begins at the same time as Spring weights for heavy haul
• Period 2: June 16 (may begin one week earlier or one week later)
• Period 3: July 16
• Period 4: September 1

Commercial Vehicle Weight and Dimension Specification: Historical Seasonal Weight Changes.

Frost and thaw depths are monitored from a network of 70 frost probe stations throughout the province. The data are used to determine the start of the Spring/Period 1 and Winter/Period 4 seasons and the placement of the thaw or frost line.

See the current frost or thaw line placement in the Frost/Thaw Contour Map.

Winter: weather dependent, subject to one meter or more frost depth readings. Trucking weights can be more significant in winter because the pavement is less vulnerable when the ground beneath is frozen, providing support.

Alberta also publishes a "Road Ban List" of major highways. Typically, the document lists weight restrictions of 90% of 75% of permitted axle weights. The bans list (a PDF file) can be accessed from: http://www.transportation.alberta.ca/522.htm.

Current frost or thaw line:

Thaw/Contour Map (pdf)