scope:

This module details the process to prepare for and carry out a geohazard assessment and report the results into Network Rail's earthworks database.

A geohazard assessment is carried out:

• when the evaluation of an earthworks examination identifies there is a risk of failure from earthworks and outside party natural slopes which warrants further investigation and analysis; or

• where the railway has been identified to be at risk from a natural slope.

This document applies to outside party natural slopes adjacent to the Network Rail boundary, where failure could pose a risk to the safe operation or performance of the railway infrastructure.

This includes:

a) outside party natural slopes (such as mountainsides);

b) coastal cliffs.

This business process does not apply to:

a) mapping of vegetation other than factors affecting slope stability;

NOTE: See NR/L2/OTK/5201 or NR/L2/TRK/5201 for mapping of vegetation

b) earthworks and natural slope drainage other than factors affecting slope stability of outside party earthworks;

NOTE: See NR/L2/CIV/005.

c) the assessment of ground movements resulting from, for example, natural cavities formed by dissolution of susceptible geologies, mineral extraction including tipping and stockpiling, landfill operations or subterranean fire.

NOTE: See NR/L3/CIV/037 and NR/L3/CIV/038.

Purpose

This module details the geohazard assessment process which is part of Network Rail's earthworks management process.

A geohazard assessment relates to:

a) Identification of hazards from natural slopes;

b) Assessment of the consequence of a natural slope failure.