Ice Control Technology with 20 Percent Brine on Highways

Abstract

Saturated brine (20 percent) is used for ice clearing to decrease the use of salt (NaCl) but at the same time maintain or increase the level of drivability and safety. A new technique makes it possible to spread brine from a truck traveling 70 km/h (45 mph) in one lane onto the neighboring lanes. The possibility of decreasing the use of salt by changing the spreading method was studied. In Funen County, 20 percent saturated brine has been used successfully to combat icy roads with frost, ice formation on wet lanes, glaze, and snow. In winter 1998–1999, the residual salt from the spreading of brine and prewet salt was measured in 1,800 places. Results showed that saturated brine is spread more evenly across the road than prewet salt, and more salt from the brine is still present on the road 2 h after spreading as compared with prewet salt. Several statistical analyses were carried out, giving a useful picture of the amount of residual salt on the roadway and indicating that more salt from brine than from prewet salt is active on the roadway and that degradation of residual salt is crucially affected by high traffic intensity. In practice, spreading of saturated brine takes effect immediately if there is frost or ice on the road, whereas dry or prewet salt takes time to become effective. Likewise, it has been shown in practice that saturated brine is effective in glaze and snow conditions, but 20 mL (4.6 g/m2 NaCl) normally is not enough. Use of saturated brine has produced such good results that within the next 10 years Funen County is expected to convert to the sole use of this method of ice clearing. The most common application is expected to be 20 mL/m2 or less, but in special cases it might be necessary to use 40 mL/m2.