Spring thaw, also known as thaw weakening, occurs in early spring when the temperatures are beginning to rise, and the snow begins to melt. Spring thaw is also the time when the most damage to asphalt pavements can occur. During the winter, water within the pavement and aggregate base freezes from the surface of the pavement down to the subgrade. Spring thaw occurs as the frozen pavement begins to thaw from the surface of the pavement down to the subgrade. While the subgrade is still frozen, water from the thawing pavement is trapped in the materials below the pavement. These saturated materials are significantly weaker, allowing heavy loads to easily damage the pavement. This is why many states implement spring load restrictions. The Minnesota state DOT (MnDOT) has estimated over $10,000,000 in savings each year, due to the implementation of the spring load restriction program.

How does spring thaw affect my parking lot?
Passenger cars will likely not cause too much damage during the spring thaw, but heavier vehicles such as freight vehicles, utility vehicles, school buses, and recycling or garbage vehicles, can cause significantly more damage than usual. MnDOT estimates that vehicle loads cause five times more damage during the spring thaw than during the summer months, meaning these heavier vehicles can severely damage your parking lot in a relatively short amount of time.

What can I do to protect my parking lot?
Preventative maintenance is a good start to protecting your pavement. Sealing cracks, and filling potholes will prevent some water from infiltrating below your pavement. Also, consider the routes taken by freight vehicles, garbage vehicles, and school buses. Have a discussion with your garbage collector or bus drivers and designate a specific route for them to take through your parking lot. If you are reconstructing your pavement, consider making these designated routes, or loading dock areas, “Heavy Duty” sections. “Heavy Duty” sections will be a thicker (stronger) pavement section that is more likely to resist these heavy loads and last longer.


Finally, consider a policy for snow removal next winter. Head out to your parking lot and check out the melting snow piles. Where is all of that water going? Is it seeping into the cracks of the pavement, or is it making its way to a storm sewer? Water is a natural enemy of asphalt pavements, and it is best to make sure the drainage around your snow piles is sufficient to quickly get the water off of the pavement.

Bituminous Roadways, Inc. is the Twin Cities’ most respected and sought-after pavement company. With more than 70 years in the industry, we provide dependable service and the highest level of quality asphalt paving anywhere. Call us today at 651-686-7001 or request a consultation. We proudly serve the Twin Cities metro and surrounding area.