scope:

Purpose

The Rock Slope Hazard Index (RSHI) is used to objectively assess and score the level of hazard presented to the railway by a rock slope.

The RSHI is based on observations of surface visible features collected during a systematic examination of the rock slope, carried out in accordance with NR/L3/CIV/065.

The RSHI uses the recorded parameters from an examination, either to determine weighed scores from detailed lookup tables, or to inform logic choices within the scoring algorithm.

By applying the individual observations within a set of lookup tables to determine weighting factors, these are combined through a series of algorithms to determine an overall RSHI score for each rock slope.

The range of possible RSHI scores is segmented into five categories, designated A to E, and termed the Earthworks Hazard Category (EHC).

The EHC can be related to the statistical likelihood that the rock slope may fail.

Although, in most cases, the rock slope is a cutting, RSHI is also applied to in-situ rock slopes exposed below track level in areas of sidelong ground.