Stopping is prohibited on long stretches due to rock or snow avalanche dangers, and the road is often closed in winter, with the carrying of snow chains mandatory during snow conditions. Helicopters are used during winter to drop explosives onto snow buildup zones above the road in order to cause controlled avalanches, and the avalanche control programme is world-renowned. However even this does not absolutely eliminate the danger that road traffic may be hit by an uncontrolled event, especially in the area of the Homer Tunnel portals. The last known fatality from an avalanche on the road was in 1983.