Report No. : GEO Report No. 68

Report Title : The New Priority Classification Systems for Slopes and Retaining Walls (1998), 117 p. (Reprinted, 2002)

Author : C.K.L. Wong

Abstract

This report documents the New Priority Classification Systems (NPCSs) for slopes and retaining walls developed as part of the GEO Slope Information System. Since different types of slope features are affected by different factors to different degrees, separate priority classification systems have been developed for soil cut slopes, rock cut slopes, fill slopes and retaining walls.

Under each system, a Total Score is calculated for each feature, reflecting the relative risk of landslide involving the feature. The Total Score is obtained from the multiplication of an Instability Score and a Consequence Score. The Instability Score is calculated based on an assessment of a number of key parameters that affect the likelihood of failure. The Consequence Score reflects the likely consequence of failure. The higher the Total Score, the higher is the priority for follow-up action on the feature generally.

Details of the scoring scheme and guidance notes for data collection and score calculation for the NPCSs, together with worked examples, are given in this report.

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