The problem
In cold regions the ground freezes deeply over winter. When it thaws, it thaws from the top down: the upper layers turn wet while the soil below is still frozen and water cannot drain away. Until the frost has gone and the layers have drained, the pavement is at its weakest and heavy axles do far more damage than usual.
Many agencies therefore restrict heavy loads on vulnerable roads each spring. The start and end dates are often fixed in advance or set by experience. Lifting too early damages the road. Lifting too late holds up local freight, farming and construction.
What to measure
- Temperature by depth with a string of temperature sensors, to follow the frost and thaw fronts through the pavement and subgrade.
- Pavement strain under passing trucks, to see the structure weaken and stiffen again.
- Air and surface temperature, to relate the thaw to the weather.
- Optionally, soil moisture sensors on RS-485.
How MT-16 is set up
One MT-16 at the roadside carries the temperature string, a few strain probes in the wheel path and a weather sensor. Temperatures are logged on a schedule; truck passes are captured as events. Every morning the data arrives by cellular network, so the thaw can be followed from the office through the whole restriction period.
What you get
- A daily view of frost depth and thaw progress at each monitored site.
- Evidence for the start and end of restrictions, site by site.
- A record that builds up year after year and helps calibrate thaw models for your network.