By Heather Brown

MINNEAPOLIS (WCCO) — We are officially in road construction season — also known as spring and summer in Minnesota.

Many of the biggest projects will include fixing the pavement. That could mean simple patching, a new layer on top or tearing it all up and starting new.

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So, how long are our roads supposed to last? Good Question.

“Well, we have two different types of road surfaces that we use, asphalt and concrete,” said Kevin Gutknecht of the Minnesota Department of Transportation. “We design the asphalt to last about 20 years and the concrete to last 35 years.”

Concrete lasts longer, but it’s more expensive. The interstates generally start out as concrete, but then get an asphalt layer on top.

Within that 20 to 35 years, how often are the roads getting patched up?

“It depends, depends on the road, depends on how much it’s deteriorated, what kind of problems there are and how much funding we have,” said Gutknecht.

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About half of our roads are more than 50 years old. Their lifespan has been expanded through rehab and repair.

How much time will an overlay buy you?

“It varies. It can be as little as five to seven years, it can be 10 to 12, again, depending on the traffic,” said Gutknecht. “We design them to last that long, but there are a lot of factors that affect it, there’s the traffic. Salt can be a factor, salt is tough on concrete. It’s not tough on asphalt.”

Whether it’s new pavement, or just a new surface on top, depends.

“We measure the quality of the ride, we figure out how much traffic is on there, and then yes, we do kind of look back and say ‘How long has it been since we’ve done something here, and if we do something now can we make it last longer, or do we wait until it’s degraded more and then we have to do a bigger fix,” Gutknecht said.

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Minnesota does a lot of research on what mixes, bases and construction methods work best in our environment.

Heather Brown