2021 Idaho winter frost/spring thaw laws and seasonal weight restrictions.
During the spring months when warmer temperatures cause the road surface to break up and generally deteriorate, the highways most affected are restricted to lower axle weights and speed restrictions.
The District will sign and mark affected state highways the day before the weight and/ or speed restrictions are in effect. The weight and/or
speed restrictions will be enforced the day after the Districts sign and mark the state highway.
On those sections of highways which are posted for legal weight, or to less than legal weight, trucks and buses weighing 10,000 pounds or
more will be restricted to 30 mph in critical areas. Speed zones will be marked with red and yellow markers. A red marker will mean speed
is restricted to 30 mph and a yellow marker will mean that legal speed can be resumed.
For information on operating restrictions for state highways posted for spring breakup limits or to check on a route of travel for construction
restrictions etc., go to 511.Idaho.gov and the trucking page.
It is important for the trucking industry to cooperate and comply with the load and speed limits. If compliance with the load and speed limits
are adhered to, the need for future, more restrictive, limits may be alleviated. Excessive violations may lead to implementation of more
This is a excellent reference and resource point for Idaho chain laws and basic seasonal weight restriction information.