On January 8, 2000, at 1230 mountain standard time, a Cessna 172P, N65710, was substantially damaged during a precautionary landing on a road near Huntsville, Utah. The flight instructor and his student were not injured. The airplane was being operated by Utah State University, Logan, Utah, under Title 14 CFR Part 91. Instrument meteorological conditions prevailed for the cross-country flight which originated from Heber, Utah, approximately 45 minutes before the accident. A school VFR flight plan had been filed. A witness reported that a snow storm "came in real fast," and conditions deteriorated in 5 minutes. The flight instructor said that they were surrounded by mountains and the "flight conditions became instrument meteorological in a matter of minutes." He said he could see a road below him and he landed. During the landing rollout, the instructor pilot discovered that the road was covered with ice. The road curved to the left, and the airplane exited the road to the right, and impacted a ditch, damaging the engine firewall and engine mounts.