The goal of ADOT&PF Snow Avalanche Programs is to improve safety for highway users by reducing the avalanche hazard in areas susceptible to snow avalanches while concurrently minimizing avalanche related traffic delays and road closures.
Avalanches cannot be prevented in all avalanche paths that affect the highway, but the encounter risk can be reduced. To help forecast avalanche hazard and the necessity for temporary traffic delays for avalanche work, ADOT&PF regularly monitors weather, terrain, and snowpack conditions. When conditions are appropriate, specially trained maintenance crews use military artillery and other methods to artificially trigger avalanches on the: Seward Highway, Richardson Highway and Dalton Highway, as well as Thane Road in Juneau. Additionally, ADOT&PF crews near Skagway have begun using an Avalauncher to reduce avalanche hazard.
The potential for avalanches changes constantly, sometimes in a matter of minutes. Not all snowstorms create avalanches, nor are all sunny days free of avalanche occurrences.
Avoiding highway avalanche areas and/or postponing your travel during the times described above will greatly reduce the probability of encountering an avalanche or being delayed for avalanche work on ADOT&PF highways.
The frequency, extent, and severity of avalanches vary depending on snowpack, weather and terrain. Many of the avalanche areas that affect the highway are marked with signs, please do not stop or step outside of your vehicle in these areas. Most of the avalanches that affect ADOT&PF highways occur between December and March, but they can also hit the highway as early as September and as late as June.There are many inherent challenges of forecasting exactly where and when avalanches may occur, what size they may be, and how far they may run. Avalanches may affect a highway before traffic can be diverted away from the avalanche hazard area.
If a naturally triggered avalanche blocks the highway while it is open to traffic, good practices include, but are not limited to, the following:
When ADOT&PF conducts avalanche hazard reduction, messages will be posted as “Alerts” on the ADOT&PF 511 system to notify highway users about potential traffic delays. Motorists can visit the website or call 511 for current road and weather information and updates on avalanche work. Electronic sign boards will also be used in some locations to display avalanche notifications.
Since it is difficult to predict how much snow will be brought down during avalanche hazard reduction work, ADOT&PF cannot estimate how long each traffic delay will take. Typically, these intermittent delays last about 45 minutes; however, longer delays are possible. The Seward Highway between Anchorage and Girdwood has been closed for 4 consecutive days due to avalanches. Always travel with extra supplies in the winter in case an avalanche blocks a highway for an extended amount of time. ADOT&PF will re-open the highway to traffic as soon as maintenance crews can safely remove the debris from the highway.
ADOT&PF avalanche hazard reduction work can also impact air traffic. During active artillery work, the FAA will issue Temporary Flight Restrictions. More detailed information for pilots about avalanche blasting can be found in the FAA Supplement for Alaska or by visiting the following website: FAA's Temporary Flight Restrictions.
Off-highway users may also be affected. If traveling off the road system near highway avalanche areas, please remember:
Occasionally artillery ordnance does not explode upon impact. Unexploded artillery ammunition or “duds” occur infrequently; but, they do pose a potential risk to hikers and others that might stumble upon them in the mountains where avalanche blasting occurs (see maps for locations). If you find any unexploded ordnance, DO NOT TOUCH IT. Mark its location from a safe distance away with a GPS, rock pile, or bright cloth. It also helps to take a photo of the ammo from a safe distance showing its surrounding area so that it may be found quickly and safely destroyed by Explosive Ordnance Disposal personnel. Report the location of the unexploded ordnance immediately to ADOT&PF at the numbers listed below or to an employee listed in the Contact Information at the bottom of the page:
Seward Highway Snow Avalanche Maps
*Note-the maps below show most but not all avalanche paths that affect the roadway
ADOT&PF is committed to improving the effectiveness of its Snow Avalanche Operations. In addition to being a member of the Avalanche Artillery Users of North America Committee, ADOT&PF has also been an active participant with the International Snow Science Workshop (ISSW). ISSW has been the ongoing forum for state of the art avalanche research since 1976. A database of all ISSW Papers and Abstracts are available online thanks to: Montana State University, the ISSW Steering Committee, Canadian Avalanche Association, and the American Avalanche Association.
General Questions about the Statewide Avalanche Program or contacts for Seward Highway Avalanche Program
Thane Road/Klondike Highway Avalanche Program
Richardson Highway Avalanche Program
Dalton Highway Avalanche Program
Statewide Artillery Program Manager