It’s that time of year again when town public works directors determine what local roads are susceptible to frost heave damage and try to protect them by limiting large trucks traveling on them.
![]() |
| Windham and Raymond road postings have been announced to limit damage caused by frost heaves over the winter as the ground begins to thaw this spring. COURTESY PHOTO |
“The main cause is the formation of ice lenses in the soil, rather than just the simple 9 percent expansion of water freezing in place, though that contributes a minor amount.” Nappi said. “As temperatures drop below freezing, a freezing front moves downward through the soil. In certain soils, water is drawn upward toward this freezing front through capillary action like how a sponge soaks up water. This happens because fine soil particles create tiny pores that allow unfrozen water to migrate toward the colder zone where ice is already forming. At the freezing front this migrating water freezes onto existing ice crystals, forming thin, lens-shaped layers of nearly pure ice (ice lenses) that grow over time. These lenses can become quite thick as more water is supplied, pushing the soil above them upward – often by several inches or more in severe cases.
Nappi said that frost heaves are particularly damaging to roads because they exert powerful upward forces from below the pavement surface, often unevenly, which the rigid or semi-rigid pavement layers like asphalt or concrete aren't designed to withstand without deforming or breaking.
According to Nappi, there are several effective ways to prevent or significantly mitigate frost heave damage.
“Since frost heave requires all three conditions – freezing temperatures, frost-susceptible soil, and a source of water – to occur, prevention strategies target one or more of these, most commonly by controlling moisture, replacing or improving soil, insulating to limit freezing depth, or using other engineering techniques,” he said. “These methods vary by application, for example roads and highways, building foundations, sidewalks, or landscapes, cost, and site conditions. Complete elimination is possible in many cases with proper design, but mitigation reducing severity is more common and cost-effective for existing structures.”
He said ways to limit damage from frost heaves include improving drainage; replacing frost-susceptible subgrade materials; adding granular base or rock caps; using geotextiles or geo-composites; and other innovative treatments.
“Frost heaves can affect many things besides roads, essentially any structure, surface, or object in or on frost-susceptible soil where freezing temperatures, moisture, and poor drainage allow ice lenses to form and exert upward pressure, Nappi said. “The damage often shows as uneven lifting, cracking, tilting, bowing, or displacement, and it's especially common for shallow or lightly loaded elements.”
Besides roads, frost heaves can affect building foundations and slabs for homes, garages, commercial buildings, driveways, sidewalks, patios, concrete slabs and railroad tracks, he said.
In Windham, the Public Works Department generally post roads in late February for heavy load limits. Once these roads are posted they remain as such until the postings are removed, generally no later than May 15. The maximum registered weight of a vehicle allowed on posted roads is 23,000 pounds or less. A list of 128 posted roads in Windham this year can be found on the Town of Windham website at https://www.windhammaine.us/
Typically, a road that can easily handle a 15-ton weight truck in summer or winter months may only be able to handle a 5-ton load during the spring thawing season. The costs of repairing or rebuilding a road damaged by a frost heave can be substantial, running into $10,000 per mile in some cases and causing potholes, cracking, and roadway and pavement bumps.
In Raymond, 49 different roads are posted for frost heaves this year. That list of roads is available online at the Town of Raymond website at https://www.raymondmaine.gov/
Raymond Public Works Director Nathan White said that Routes 85, 121, 302 and Egypt Road will be exempt from this posting because they are roads that are maintained by the state of Maine. <
To learn more about frost heaves and Maine’s independent meterologist Jason Nappi, visit https://jasonnappiweather.com/ <















