CGRG Bibliography of Canadian Geomorphology
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Author : Bunce, C.M.
Date : 1994
Title : Risk analysis for rock fall on highways
Publication : Unpublished M.Sc. thesis. University of Alberta, Edmonton
Issue :
Page(s) :
Abstract
Transportation corridors through mountainous terrain are often susceptible to rock fall hazards. In 1982 a rock fell on a vehicle killing a woman and disabling her father on B.C. Highway 99. The father successfully sued the provincial Ministry of Transportation and Highways. The Supreme Court of Canada and subsequently the British Columbia Supreme Court decided that the Ministry was at fault for not preventing a readily foreseeable event that might harm users of the highway. This research demonstrates a method of rock fall impact mark mapping supplemented by documented rock fall records, to establish a rock fall frequency. A methodology for assessing the risk of loss of life due to rock fall is also developed. This methodology is applied to the above case and the results compared with accepted societal risks. The Rockfall Hazard Analysis System, developed by the U.S. Federal Highways Administration, is also correlated with the risk analysis results at this site. The risk analysis indicates that the risk posed by rock fall is comparable to other risks in society and may be within levels proposed for other types of slope instabilities. On a route like B.C.'s Highway 99, there are a large number and wide distribution of potential rock falls. Due to the expense of remediating each one, it is not considered practical to control all the potential rock falls. As a result, society must accept some level of risk. In finding the Ministry at fault in the Just case, the British Columbia Supreme Court may have set the acceptable level of risk for injury or death due to rock fall below a level that is economically achievable or considered reasonable compared with other accepted risks.
Bibliography of Canadian Geomorphology