Preparation and maintenance of pistes A review of state-of-the-art knowledge & methods

Fabian Wolfsperger, Hansueli Rhyner and Martin Schneebeli

WSL-Institute of Snow and Avalanche Research SLF, Davos, Switzerland

Introduction We present the new handbook of piste preparation, which is the only source of information that provides ski resort operators with methods and knowledge for quality assurance of the central product of a winter sports destination - the ski slopes, cross-country ski runs and snow parks. The new edition contains a completely new chapter, which also makes the layman understand the physical processes and the resulting properties of the snow. For the first time, current snow production technologies are compared. The completely revised book bridges the gap between research

findings and day-to-day practical application on ski slopes. It provides important know-how to meet the increasing Weitere Informationen zum neuen Handbuch Pistenpräparation und demands on snow sports offers, while the climatological conditions are becoming increasingly unfavorable. Pistenpflege

Porous ice Firn Old snow New snow

915–830 kg/m3 830–550 kg/m3 550–250 kg/m3 250–50 kg/m3 snow strengthening from sintering

3 3 3 3 3 4.0

805 kg/m 784 kg/m 577 kg/m 424 kg/m 104 kg/m ]

Science of Snow - • Basic structural properties 3.5 • Thermal properties 3.0 • Snow processes 2.5 • Mechanical properties 2.0 • Formation of natural snow • Machine-made snow 1.5 Grain size

rel. strength increase [ increase strength rel. 1 mm 2 mm 4 mm 1.0 0 3 6 9 12 15 18 21 24 Microscopy and micro CT images DH WC DH WC DH WC DH WC Natural snow time [h] van Herwijenen et al., 2013 of machine made snow of Meteorological factors different grain size and wetness , Lake Louise Beaver Creek Are, SWE Lake Louise Davos CH affecting snow SLF. • Atmosphere

• Thermal balance on the snow surface 25

]

3

Preparing and maintaining ski pistes 20 [kg/dm • The optimal ski piste 15 • Principles of snow consolidation

10 strength • Snow preparation in accordance with snow and weather conditions • Machines and their optimal use 5 with temperature gradient shear without temparature gradient without temparature gradient fine-grained 0 0 50 100 150 200 Preparing and maintaining a ski racing track time [h] Guily et al., 1991 • Goals of racing track preparations water input vs. percolation depth • Preparatory work 90

80 • Watering a ski racing track ] 70 • Chemical snow hardening kalter Race piste watering using an on-board 60 Schnee water injection system • Snow clearing 50 warmer Penetration of a piste machine on new snow and after 3 preparation runs 40 Schnee 30 20

Preparing and maintaining cross country ski tracks [cm depth percolation 10 • Goals of racing track preparations 0 0 20 40 60 • Preparatory work Watering experiments on snow of 2 • Watering a ski racing track different grain sizes and densities water input [l/m ] • Chemical snow hardening Attractions • Snow clearing Cross tracks Freestyle parks Halfpipes parks XC track quality increase due to high pressure and low speed preparation • Airbag Jump Ski-/Bordercross Slopestyle Superpipe • Photo Jump (professional) (professional) (professional) Constructing and maintaining a snow park • Speed Track Freestyle Park • Toboggan/- • Large Medium Pipe Freeridecross • Freestyle Parks Tube Track • Medium • Wall < 4 m Fleece cover on a XC WC track (Korea) to • Snow • Small • Cross tracks prevent melting and softening Playground Small Pipe Funline Kids Park • Halfpipes … • Wall < 1.5 m Energy Water Ecology Socio- Micro economics Snowfarming climate Technical Snow Snow management snow accumulation Natural Snow Innovative • Standardized workflows and snow management Earth technologies management system Piste tools works «Snow condition Trained • Technical snow and micro climate How» staff • Piste preparation Piste Piste stress preparation Weather • Snowfarming Climate change forecasts Customer • Further measures Adaption strategies needs Quality • Climate change and snow guarantee Efficient use of Cost Customer Construction, maintainance and terrain adaptions for a halfpipe resources reduction & improvement satisfaction Snow height loss in a snow farming depot due to thermal radiation of concrete walls Measuring methods and equipment (Krämer et al. 2017) • Snow measurements • Meteorological parameters • Snow cover models • Snowmaking app Terrain adaptions for ski pistes followed by successful re-vegetation Simple explanation of the ALPINE 3D model chain • Tools for snow park constructions SLF snow meter to quantify ICE CUBE device to quantify the (Bernhard Krautzer) snow density and wetness microstructure of snow (SSA)