Reliable, effective, safe and simple: Wyssen Avalanche Tower LS12-5.

System setup and function

Sprengmasten beschriftet und Englisch

To trigger an avalanche, a coded command is sent from the control centre WAC.3 to the control system of the deployment box to initiate blasting. The deployment box contains 12 prepared explosive charges, which can be individually deployed by remote control. When the explosive charge is dropped, two igniters are pulled and the explosion is set off after a time delay. The charge remains hanging from a cord at a pre-set height above the snow cover, which is completely dropped after blasting. To reload explosive charges the complete deployment box is lifted from the tower by helicopter and brought to a station building or warehouse respectively.

Deployment Box

The solar panels, antenna and a flashing lamp are mounted on the outside of the deployment boxes. The dropping mechanism, the electronics and 12 prepared explosive charges are on the inside of the box and protected against the elements. The compact and sealed design means that maximum system reliability is attained.

Magazinkasten

Charge Containers

The explosive charge consists of two orange half-shells with pre-mounted SZ 83 percussion fuse, which are assembled with 5kg of explosives. The charges are assembled by the operator on-site. We deliver the charge containers and the canvas bag for the retaining cable (7.5m) Explosives and other pyrotechnical elements are purchased directly by customers from the appropriate suppliers.

Ladungsbehälter-Magazin

Effect

The greatest degree of success for controlled release of avalanches is achieved by a remote-controlled detonation of an efficient explosive at the right time and in the right place.

From the operator’s point of view, a blasting installation must be extremely reliable and effective as well as being simple to operate and maintain. The installation in the terrain must be as simple as possible and the interference of the installation must have a low impact on this sensitive environment. The Wyssen avalanche tower fulfils these requirements ideally.

Smallest residual risk thanks to the largest effective range

  • blasting above the snow with bigger charges (5kg) gives the maximum effective range up to 260m in diameter
  • explosives with high detonation speeds produce N-shaped pressure waves which has been proven to lead to the best release effect, particularly at a greater distance from the detonation point
  • the possibility of positioning the installation in higher locations in addition to suspending the charge higher enables the effect to be reached in locations of pressure shadow (in couloirs, behind terrain ribs)
  • release of smallest quantities of snow possible, thanks to the greatest effectiveness
  • very good stability test for assessment of the local avalanche danger

Maximum reliability

  • no critical or moving parts are exposed to the weather, thanks to its intelligent concept
  • the solar power supply or wind generator avoids the necessity of vulnerable supply lines in the terrain

Reduced closure times thanks to rapid release, around the clock and in all weathers

  • remote-controlled installations allow operation around the clock
  • very rapid operation possible
  • closure times are reduced in the rule to a maximum of 30 minutes
  • clearing away avalanche snow is usually dispensed with, since the avalanche run-outs are short due to the release of smaller portions

Highest cost-effectiveness

  • low investment and operating cost in comparison with permanent constructional protective measures
  • lowest operational costs thanks to its ingenious system concept
  • damage to the infrastructure is avoided by the release of smaller portions
  • economic benefits thanks to reduced closure times

Highest degree of safety for the operating staff

  • no staff in the danger area thanks to remote-controlled release
  • preparation of the charges takes place in protected areas
  • the mobility of the deployment boxes means that no maintenance is necessary in the terrain

The smallest interference in nature is very environmentally friendly

  • foundation only uses 1m2
  • short construction times in the terrain simplify planning and implementation
  • blasting over the ground prevents damage to the vegetation cover
  • dismantling after operating life possible without any problems

Technical Data

General Information

Wyssen Avalanche Tower LS12-5
Weight deployment box complete incl. charges approx. 600 kg
Dimensions Deplyment box (l x b x h) 1600 mm x 1050 mm x 1200 mm
Dimensions of tower (h x ø) 8000 mm x 300 mm
Inclination of tower 15° in direction of slope
towards the valley

Loading capacity

Number charges per launcher 12 pcs.
Amount of explosives per charge max. 5 kg

Mechanism in the deployment box

Drive unit DC motor
Time for rotating one position approx. 13 s
Transmission Gearbox gear motor
Transmission Karussell Ritzel-Zahnkranz

Power supply

Battery in deployment box supplied by solar panlsl 12 V

Operating software Wyssen Avalanche Control Centre WAC.3

The latest software generation including new hardware for operating, monitoring and data storage of the well-proven Wyssen Avalanche Tower LS12-5.

  • intuitive web based operating interface
  • extensive additional features (e.g. outside temp., snow height)
  • operation independent of location
  • multiple release from Avalanche Towers possible
  • monitoring of systems 24/7
  • automatic documentation and archiving of activities and system status

Data connection via mobile network or radio

Transportation by Helicopter

The deployment box is transported by helicopter to the towers in the terrain. Thanks to the guiding system the pilot is able to perform the placement on the tower on his own without a flight assistant.

The deployment box orientates itself automatically in the correct position. A safety switch detects the correct position, after which the system becomes operational. The operation can verify the placement of the deployment box on the correct tower on the operating interface immediately thanks to the GPS receiver installed. The system will not be activated if placement is incorrect.

When all charges are used or after end of season the deployment box is being retrieved from the tower by helicopter. Thanks to the special Wyssen Heli link no flight assistance is needed in the terrain.

Hubschrauber-mit-Magazin

Tower in the Winter with Deployment Box

Mast-Winter

Tower in the Winter without Deployment Box

Mast-Sommer 2

Safety Regulations

Transport

The helicopter company must have an authorisation in order to carry loaded deployment boxes. Depending on the country, the intended flight routes with loaded deployment boxes must be approved by the flight authorities.

Flight routes

The helicopter routes taken by which avalanche tower deployment boxes are transported must be so chosen that from the loading place to the avalanche tower a distance of at least 500m is maintained at all times and in all directions away from any persons not involved in the operation. Flying directly over populated areas, open roads as well as people, technical installations (e.g. mountain cableways, mountain restaurants and relay stations) and open ski runs is prohibited.

Personnel

Only those persons are permitted to operate and handle the installation who are in possession of a valid certificate for the artificial release of avalanches with explosives and who have attended a certified course by Wyssen Avalanche Control AG. Furthermore, it is very important that the operating staff have the corresponding training and experience for risk assessment, planning of measures, implementation of measures as well being able to assess secondary avalanches and avalanches that could be larger than expected.

Storage

Approval for storing explosives: for each tower location authorisation must be requested by the customer from the responsible authorities for storing explosives in the avalanche tower deployment boxes during the period of operation.

Basic Principles of Controlled Avalanche Release

It is known from practical experience and from the theory of avalanche release in deep winter, that the effect of a detonation above the snow cover leads to the best results with respect to residual risk of unpredictable avalanches. The explosives used should produce a high detonation speed and a large volume of gas with a high work factor. Tests with numerous experiments show that explosives with the above-mentioned properties and charging positions above the snow cover give the highest effective ranges.
The following table from the WSL Institute for Snow and Avalanche Research SLF Davos Report no. 53/1996 shows the approximate effective ranges for dry new snow of various explosive charge sizes in different positions with respect to the snow surface.

In order to test and to safeguard the avalanche release zone, the whole of the potential release area must be subjected to an additional stress (e.g. by a detonation). This is necessary, because the location of the so-called “hotspots” (super weaknesses) are not known in advance. An acceptable residual risk after blasting operations is only then reached if these “hotspots” have been subjected to a sufficiently high additional stress by high strain rates at the weak layers within the snow cover.

For more information:

Height of detonation point Charge size Radius of effective range
to prevent a natural release
Radius of effective range
to prevent a release by a single skier
Blasting above the snow (+3 bis 3.5 m) 4 to 5 kg 120 to 130 m 70 m
Blasting above the snow  (+2 bis 2.5 m) 1.5 to 2.5 kg 80 to 90 m 50 m
Blasting above the snow  (ca. +1 m) 4 to 5 kg 80 to 90 m 50 m
Blasting above the snow  (ca. +1 m) 1.5 to 2.5 kg 60 to 70 m 35 to 40 m
Surface blasting 4 to 5 kg 50 to 60 m 30 to 35 m
Surface blasting 1.5 to 2.5 kg 35 to 40 m 20 to 25 m
Blasting in snow (ca. -0.2 m) 4 to 5 kg 40 m 25 m
Blasting in snow (ca. -0.2 m) 1.5 to 2.5 kg 25 m 15 m
Blasting in snow (-0.7 m) 1.5 to 5 kg 10 m 5 to 10 m
Mortar 12 cm (0 m) 3 kg 40 m
RPG 8.3 cm (0 m) 0.7 kg 20 to 25 m 10 to 15 m
Mortar 8.1 cm (0 m) 0.6 kg 15 to 20 m 10 m

Source: SLF Mitteilung Nr. 53

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