Item: SYSTEMATIC EVALUATION OF THE LOCAL CRITICALITY OF RECENT OVERLOADS AND TEMPERATURE EFFECTS TO MITIGATE AVALANCHE RISK FOR TRAFFIC ROADS
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Title: SYSTEMATIC EVALUATION OF THE LOCAL CRITICALITY OF RECENT OVERLOADS AND TEMPERATURE EFFECTS TO MITIGATE AVALANCHE RISK FOR TRAFFIC ROADS
Proceedings: Proceedings, International Snow Science Workshop, Whistler, BC, Canada, 2026
Authors:
- Camille Ligneau [ LISTIC – University Savoie Mont Blanc, Annecy, France ]
- Frédéric Pourraz [ LISTIC – University Savoie Mont Blanc, Annecy, France ]
- Alain Duclos [ ALEA (Avalanches: Location, Research and Action), Aussois, France ] [ data-avalanche.org association, Aussois, France ]
- Jill Chevalier [ LISTIC – University Savoie Mont Blanc, Annecy, France ]
- Gilles Mauris [ LISTIC – University Savoie Mont Blanc, Annecy, France ]
Date: 2026-09-28
Abstract: The closing of roads due to snow avalanches is a common issue in mountainous regions during winter. The decision to temporarily restrict traffic access to avalanche-exposed roads often relies on human expertise, fed by a large variety of parameters. The diversity of information nature and sometimes the scarce availability of local data can therefore induce a very complex decision-making process, prone to oversights. Developed and practiced for about two decades, a decision-making support process called CRISTAL (ISSW 2023) is now subject to research studies. This approach is based on the criticality of five criteria: topography, current avalanche activity, weak layer properties, recent overloads and temperature effects. It has recently been upgraded to a hierarchical expert system (involving multiple levels of aggregation) based on fuzzy logic, which properly handles the approximate truth coming from scattered field measurements and observations. The system outputs a vigilance mode (relaxed / suspicious / alert / gamble) depending on the criticality of the five criteria. So far, the evaluation of each criterion is done manually by the user, who must personally seek information about the current conditions. To make the system more operational in three French alpine departments (Savoie, Isère, Hautes-Alpes), we aim to automatically gather all available information and process them to assess criticalities in real time for specific slopes. We present here a part of the up-to-date expert system that deals with the meteorological data available in the French Alps. This subsystem, part of the first aggregation level, delivers a level of criticality for the criteria of recent overloads and temperature effects (the parts concerning the other criteria will be treated in separate works). First, the subsystem estimates weather-related variables at the slope scale, such as snow surface temperature, thawing, and recent overloads due to fresh snow, wind-blown snow or rain. Once the local variables are assessed, they are each assigned a fuzzy value (e.g. the amount of fresh snow can be none / low / moderate / high) and processed through a set of fuzzy rules to deliver a level of criticality (e.g. a leeward slope after a strong wind-transport event raises a high criticality for the recent overload criterion).
Object ID: ISSW2026_O2.2.pdf
DOI: https://doi.org/10.15788/1790098551
Language of Article: English
Presenter(s): Camille Ligneau
Keywords: Avalanches, Traffic roads, Criticality, Expert system, Fuzzy logic.
Page Number(s): 785 - 792
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