The following is excerpted from Snow & Ice Control Operations published by the California Department of Transportation.
Jet-Roofs
The "jet roof" alters the wind patterns that normally blow across the ridge area creating dangerous snow cornices.
GAZ-EX*
Caltrans 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.
LoCAT**
LoCAT 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 The LoCAT units are replacements for the outdated U.S.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.
Avalauncher***
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.