Michigan counties are activating annual frost laws to protect roads

Weight restrictions and reduced speed limits for heavy vehicles help protect roads from damage during spring thaw.

Most Michigan drivers can testify that the harsh weather this winter has certainly impacted many roads. Pothole dodging is a daily experience for many drivers throughout the state now that the weather has started to warm and snow cover on roads has receded.

Frost laws, otherwise known as seasonal restrictions on traffic weight limits and speeds on roads subject to thaw weakening, is one method that the state and local jurisdictions have at their disposal to protect local roads during the annual spring cycle of freezing and thawing.

Generally, these conditions most often occur during March, April and May. This is the time period in Michigan when frost is still in the ground. The ground intermittently warms and cools as warmer, spring weather varies with colder, more winter-like weather conditions. This up and down weather pattern often results in pavement buckling and heaving. Road surfaces can crack and develop stress fractures from too much weight during this critical time. At other times, the base structures of roads can be weakened when surface thawing results in water building up and damaging pavement. The date frost laws go into effect annually is determined by local road officials based on the current conditions. Often, in the Michigan county in which I reside, this occurs on March 1. This year, with our prolonged winter, county frost laws did not go into effect until March 17. The length the frost laws are in effect is also determined locally and is once again dependent on weather conditions.

By law, when conditions merit, the Michigan Department of Transportation (MDOT) and county road commission can enact weight restrictions on any roads not designated as all-season routes. Section 257.722 of the Michigan Vehicle Code, Act 300 of 1949, provides details of the seasonal restrictions. There are some special exemptions allowed for those hauling agricultural commodities and public utility vehicles.

Technically, Michigan’s weight laws apply to all vehicles, but commercial haulers are those most impacted as their vehicles most typically are of the size and weight being restricted by these laws. Depending on the design and materials used in constructing a particular road, the legal axle weight can be reduced by either 25 percent or 35 percent on that road until officials ascertain conditions are once again safe for use by heavier vehicles. On certain roads, heavy vehicles may also be limited to driving no faster than 35 mph regardless of the posted limit that still applies to lighter vehicles.

Michigan certainly is not the only state in this predicament. Many other states as well as Canadian provinces experience very low winter temperatures and enact similar laws to protect their roads.

The County Road Association of Michigan provides an online update of the current weight restrictions for every Michigan county. For up-to-date information on reduced-weight restrictions on state roads, visit Michigan Department of Transportation (MDOT) for their latest online bulletins or call their 24-hour phone line at 800-787-8960. Truckers can consult an online map of Michigan to determine routes that are legal for their size vehicle during the annual seasonal weight restriction period.

Obeying frost laws in your area will help protect roads from deterioration. This year’s very cold, snowy, prolonged winter has been especially hard on roads, municipal water systems and roofs on many structures. Planting may be delayed this spring for both farmers and home owners. Orchards, vineyards and homeowner trees and plants may have suffered more winter damage than usual.

For more information about when to plant this spring, or if you have concerns about plants that seem to have not over-wintered well, visit the Michigan State University Extension website. If you cannot find the information you are looking for, you may contact your local Extension office, or submit your question to an Extension expert in Michigan or Extension universities in other states. 

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