What do spring load restrictions have to do with asphalt?

Written by Bit Roads on . Posted in Uncategorized

What are Spring Load Restrictions?

Since 1937, Minnesota has enforced spring load restrictions each year as temperatures begin to rise. These spring load restrictions are determined for each state, county and city road, and they restrict the weight of a single axle to less than 5-10 tons. This restriction will not affect any commuter vehicles, but it does have a big impact on commercial vehicles. Freight vehicles, dump trucks, and large construction equipment will be severely limited by the number of roadways that they are allowed to drive on.

Why Spring Load Restrictions?
During winter, water beneath the pavement freezes from the top down. The frozen ground will actually strengthen the soils supporting the pavement, allowing winter load increases! Similarly, during spring, the frozen soils thaw from the top down. This creates a problem because the thawed water is trapped beneath the pavement by the layers of still frozen soil. This trapped water will saturate and weaken the soils that are supporting the pavement above. Due to the weaker support, the overall strength of the pavement structure is compromised. Therefore, by restricting heavy vehicles from using certain roads, the state, county and city DOT’s can prevent these roads from failing early. 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 do Spring Load Restrictions affect my parking lot?
The spring load restrictions do not apply to utility vehicles, school busses, and recycling or garbage vehicles (also vehicles transporting milk, but that likely doesn’t affect you). This means that these vehicles can legally be overweight during the spring thaw. MnDOT estimates that vehicle loads cause five times more damage during the spring thaw than during the summer months, meaning these overweight 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 garbage vehicles or school busses. 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 “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.

With more than 70 years experience in the Twin Cities metro area, Bituminous Roadways is the expert in everything asphalt; Call 651-686-7001 for a free estimate or pavement consultation.

Information Source: http://dotapp7.dot.state.mn.us/research/seasonal_load_limits/thawindex/tfs_slr.asp
MnDOT Seasonal Load Limits:
http://dotapp7.dot.state.mn.us/research/seasonal_load_limits/sllindex.asp

Bituminous Roadways, Inc.
(651) 686-7001
1520 Commerce Drive
Mendota Heights, MN 55120

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