Assessment of the hazard from rock fall on a highway

Abstract

Rock falls can cause delays, damage, injury, and death to highway users. In 1982, a rock fell on a vehicle in the Argillite Cut on British Columbia (B.C.) Highway 99 killing a woman and disabling her father. The father successfully sued the provincial Ministry of Transportation and Highways for damages. The Supreme Court of Canada found that the Ministry could readily foresee the risk that harm might befall users of the highway if it were not reasonably maintained and that maintenance could be found to extend to the prevention of injury from falling rock. A risk analysis methodology can assess the probability of loss of life due to rock fall. Rock fall impact-mark mapping supplemented by documented rock fall records was used to establish a rock fall frequency. The risk of rock fall on this highway in 1982 can be compared with accepted societal risks. For the Argillite Cut, the probabilities of death of a one time user and a daily commuter on the highway were 6 × 10 -8 and 3 × 10 -5 per year, respectively. The annual probability of a rock fall causing a death in the exposed population was 8 × 10 -2 in the Argillite Cut. This was higher than the level of risk now commonly accepted in some industries and large engineering projects.Résumé : Les chutes de roches peuvent causer des retards, dommages, blessures et pertes de vie aux usagers des routes. En 1982, une roche est tombée sur un véhicule dans l'Argillite Cut sur la route 99 en Colombie-Britannique, tuant une femme et invalidant son père. Le père a poursuivi avec succès pour dommages le ministère des transports et des routes de la province. La Cour suprême du Canada a trouvé que le ministère pouvait facilement prévoir que les usagers encourraient des risques si la route n'était pas raisonnablement bien entretenue, et que l'entretien devrait s'étendre à la prévention de blessures résultant de la chute d'une roche. Une méthodologie d'analyse de risques peut évaluer la probabilité de perte de vie résultant de la chute d'une roche. Une cartographie des points d'impacts de chutes de roches avec comme ajout les dossiers des chutes de roches documentées a été utilisée pour établir une fréquence des chutes de roches. Le risque de chute de roche sur cette route en 1982 peut être comparé aux risques acceptables par la société. Pour l'Argillite Cut, les probabilités de décès pour un seul passage d'un usager et pour un passage journalier d'un banlieusard sur cette route étaient de 6 × 10 -8 et 3 ×10 -5 par année. La probabilité annuelle qu'une chute de roche cause un décès dans la population exposée était de 8 × 10 -2 dans l'Argillite Cut. Ceci était plus élevé que le niveau de risque présentement accepté dans certaines industries et dans de grands projets d'ingénierie.

Quantitative assessment of the residual risk in a rockfall protected area

“…This observation is in agreement with what has been found elsewhere for rockfalls (i.e. Bunce et al 1997;Corominas 2000;Chau et al 2003).…”

Rockfall risk assessment for pilgrims along the circumambulatory pathway, Saptashrungi Gad Temple, Vani, Nashik Maharashtra, India

“…The quantitative risk assessment for the life loss of the pilgrims performing the parikrama along the two parikrama path at the Saptashrungi Gad Temple, Vani, Nashik is based on method proposed by Bunce et al (1997) and Fell et al (2005). Three important conditions were considered for the risk assessment which is as follows (figure 5); Condition-1: direct impact of rockmass blocks against walking pilgrims, Condition-2: impact of walking pilgrims on fallen rockmass blocks, and Condition-3: impact of falling rockmass block on standing pilgrims.…”

“…After the calculation of normalized frequencies for every rockfall classes, the temporal spatial probability and the vulnerability of the pilgrims has been calculated according to condition-1 using below equation (Bunce et al 1997;Fell et al 2005);…”

“…Keeping vulnerability and risk of rockfall in the area; a systematic risk analysis has been performed based on highly used approaches proposed by various researchers (Bunce et al 1997;Fell et al 2005;Roberds 2005). Simple slope stability studies have been carried out by various researchers in hill slope but very few risk analysis are reported (Singh et al 1990(Singh et al , 2009Singh 2008, 2011;Vishal et al 2010;Umrao et al 2011;Verma et al 2011).…”

Comparison between qualitative rockfall risk rating systems for a road affected by high traffic intensity

“…Transportation corridors in a great deal of regions are often liable to undergo rockfalls, which cause a major hazard for motorists as well as a large amount of damage and injuries (Bunce et al, 1997;Hungr et al, 1999;Budetta et al, 2005). Over the last two decades, several qualitative risk rating systems (QRSs) have been proposed in order to reduce the potential consequences of rockfalls, and information technology systems (involving the use of electronic data sets, video images, lidar-based technologies, and GIS) have been implemented by several authors and transportation agencies in the USA, Canada, Australia and elsewhere (Pierson et al, 1990;Franklin and Senior, 1997;Bateman, 2003;Rose, 2005;Drumm et al, 2005;Liang et al, 2006;Pack et al, 2007;Youssef and Maerz, 2012;Russell et al, 2008;Mekni et al, 2008;Ferrero et al, 2011;Lato et al, 2012;Mignelli et al, 2012).…”