ALPENA The Michigan Department of Transportation and county road managers are getting ready to set frost laws as spring gets closer.
According to the County Road Association of Michigan website, these restrictions are starting to go into effect downstate, and limit the weight of vehicles on pavement as the ground is thawing out.
Washtenaw and Livingston counties posted their frost laws March 1, and Genesee, Lenawee and Monroe County restrictions went into effect Friday.
When the ground thaws under the surface of a roadway, the pavement becomes more vulnerable to damage, such as potholes and cracks, said Eric Precord, transportation maintenance coordinator for MDOT's North Region Transportation Service Center in Alpena.
"Roads that are mediocre get worse and we can't do much," he said.
So heavily-loaded vehicles are restricted until conditions improve.
Crews will be out filling potholes as needed, he said. Other problems, such as heaving pavement joints, bumps and dips can recover naturally as the ground dries out.
To measure the depth of the frost in the ground, MDOT has installed sophisticated sensors, called Road Weather Information Systems, across the state. One is located at the intersection of M-65 and M-32 near Cramer's Truck Stop in Lachine.
"It looks like a TV tower off a house, but with a few more attachments and cameras," Precord said.
A short distance away, embedded in the pavement is a puck designed to provide information on road ice, the temperature, moisture, even the amount of salt that has been applied, he said. A second sensor is an electronic frost probe that measures subsurface temperatures and conditions.
All of the data can be downloaded remotely and examined, and provide highway workers with information they need to maintain the roads as economically as possible. The data also can be used to warn motorists about dangerous conditions ahead.
On Friday, the probe indicated the frost is five feet deep under the wheel track where tires hit the pavement, Precord said. When frost laws go into effect, they could last a week or two longer than normal, because of this depth, which resulted from an unusually harsh winter.
The speed at which frost comes out of the ground is affected by sunshine, periods of high or low temperatures, rain, snow and other weather situations, he said. The restrictions prevent more damage from taking place, and once the pavement settles back down, they are canceled.
For current pavement conditions and frost laws, go to www.micountyroads.org/weight.php
Betsy Lehndorff can be reached via email at firstname.lastname@example.org or by phone at 358-5693. Follow Betsy on Twitter @bl_alpenanews.