Posting Weight Limits During Mud Season

Municipalities have authority under RSA 231:191 to set maximum weight limits upon the Class IV, V or VI highways under their regulatory control, and often use that authority in the months of April and May. The winter is coming to an end, and the soils and pavements of highways freeze during the cooler overnight hours and then thaw during the relatively warm daylight hours. This “freeze-thaw cycle" can cause pavement to crack or break, and potholes to open. Once the pavement is open to infiltration of surface water from rain and melting snow, the overnight freezing and expansion of the underlying soil creates frost heaves (also called “tenting") and leads to permanent failure of the surface. On an unpaved highway, the surface materials absorb water during the day, and turn to mud when the water can’t infiltrate into the frozen layers below. Heavy vehicle movement in the mud causes rutting, which traps even more water in the next cycle. If heavy vehicles can be kept off the roads until the freezing weather has passed, it is possible to avoid significant and expensive damage to the road.

The statute allows governing bodies to respond and close roads to vehicle movements until the roads dry and the likelihood of damage is reduced. The fact of the closure must be posted on signs that will advise drivers of the closure before they enter the area. If a person violates the restriction, the law allows for both criminal penalties and civil liability to pay for restoration of the damaged area. The cost of restoration could be substantial.

A highway closure may cause hardships for homeowners who need to receive fuel deliveries, or for businesses located on a closed section. The law permits the governing body to try to reduce these hardships either by granting an exemption to a particular user, or by imposing restrictions on use. For example, an oil delivery truck could be required to use the road prior to 10:00 a.m., when it is more likely that the surface is still somewhat frozen from the overnight drop in temperature, or deliveries could be based on a weather forecast when the temperatures are as low as possible. An impacted business has the right to request a public hearing to show that the weight limit significantly interferes with business and to offer up a bond for the estimated cost of restoration of the road. This shifts the risk of damage over to the business, and away from the taxpayer.

Municipalities typically lift the restrictions once the weather of “mud season" has passed, but extended closure may be justified. If a road has been seriously damaged, there may be a real need to keep the restriction in place until repairs can be achieved. In these difficult times, this may take longer than it has in the past. Thus, quick action early in the season may cause temporary inconvenience but save a great deal of expense and major inconvenience in the future.

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