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Avalanche Control

The following is excerpted from Snow & Ice Control Operations published by the California Department of Transportation.


Photo of jet roofsThe "jet roof" alters the wind patterns that normally blow across the ridge area creating dangerous snow cornices.



Photo of GAZ-EXCaltrans uses the GAZ-EX system developed by Schippers, S.A. of Le Touvet, France for the majority of its avalanche control. The GAZ-EX utilizes stored propane and oxygen piped into a fixed cannon located in an avalanche starting zone, directing a blast toward the ground. The system is remote controlled and is considered to be more effective and have a higher factor of safety than any other currently available system. These units have been placed throughout the state [California] to control areas that have had historical avalanche problems.



Photo of LoCATLoCAT commercially made artillery guns are available as a back up to the GAZ-EX system. The LoCAT units are replacements for the outdated U.S. military 75 mm recoilless rifles that were retired from active duty with Caltrans in 1997. The LoCAT system utilizes compressed air to propel a seven-pound explosive payload to the target area.



In some parts of the state, for close range avalanche control work, a low-pressure inert gas propelled projectile is fired from the Avalauncher. This device has limited range, but is simple to operate at a relatively low cost.

Hand Charges

The last resort in the CalTrans avalanche control arsenal is the deployment of explosive hand charges. This operation is very time consuming and requires trained and certified personnel. These handcharging operations often take place during the most extreme conditions on the snow laden cornice areas over looking the highway.

* GAZ-EX is a trademark of Schipper S.A.
** LoCAT is a trademark of SSE, Inc.
*** Avalauncher is a trademark of Avalanche Control Systems.