Frost boundary measurement
VTI has developed a measuring system, "Tjälstav 2004", for measurement of the frost boundary in soil. The system is a modern variant of the Gandahl frost gauge technique.
The system enables measurement of the bearing capacity of roads during the spring thaw. The system can also be used for automatic monitoring of the freezing risk in, e.g. water pipes and sewage lines.
In the standard technique, the temperature is measured at each 5 centimetres down to a depth of 2 meters. The system allows automatic recording of the temperatures, and can furnish real-time information on when the roads are passable during spring thaw periods to interested parties such as road maintenance providers and forest transport firms.
Measurement data are transferred wirelessly from the test site via a GSM modem to an Internet server, or directly to a PC, where updated temperature profiles can be read. Compared to Gandahl devices, the indicator fluid is replaced with electronic temperature sensors which record the current temperature profile in the soil.