NR NR/L2/CIV/086 ISSUE 10 PDF

This business process applies to all earthworks within the boundary of the Network Rail infrastructure (including approach embankments, approach cuttings, tunnel cuttings, slopes above tunnel portals, nailed or reinforced soil structures and any embankment that also acts as a coastal, estuarine or river defence – irrespective of its height).

NOTE 1: Approach embankments applies to overline bridges that are equal to or greater than 3 metres high, except those owned by a highway authority, roads authority or other competent authority.

NOTE 2: Reinforced soil structures applies to those whose face angle is less than or equal to 70 degrees to the horizontal.

It also covers outside party slopes which may impact the infrastructure, and can be examined using the Soil Cutting Hazard Index (SCHI), Soil Embankment Hazard Index (SEHI) and the Rock Slope Hazard Index (RSHI).

Where the outside party is unable to provide a satisfactory management policy for the slope, or demonstrate by other means that it is being managed in a satisfactory manner, the slope will, so far as is lawful, be subject to a cyclical examination.

This business process does not apply to:

a) examinations specifically carried out to assess ground movements resulting from mineral extraction, landfill operations or a subterranean fire (refer to NR/L3/CIV/037);

b) the examination of vegetation (other than the factors affecting slope stability) (refer to NR/L2/OTK/5201);

c) examinations specifically carried out to assess drainage condition and structural integrity (refer to NR/L3/CIV/005);

d) the examination of nailed or reinforced soil structures steeper than 70 degrees, retaining walls and gabion walls – other than the factors that may indicate instability of the slope (refer to NR/L3/CIV/006);

e) the examination of coastal, estuarine or river defence works that are not also embankments (refer to NR/L3/CIV/006);

This business process does not cover:

1. Emergency evacuation procedures;

2. Operational health and safety requirements but the safety of site operatives shall be taken into account when planning examinations, interventions and mitigations. In addition the provision of safe access for future maintenance and examination activities shall be considered during the design and construction of intervention and mitigation works;

3. The organisational or commercial responsibilities for delivering the requirements of this business process;

4. The examination of an earthwork: this is covered by NR/L3/CIV/065.

Purpose

This process outlines the procedures that manage the geotechnical controls mitigating the risks of:

a) loss of track support and/or track geometry;

b) Slope failure leading to loss of kinematic envelope and/or track geometry.

Threats that can lead to these risks are:

a) scour;

b) adverse/extreme weather;

c) inadequate legacy earthworks including long-term degradation;

d) impact of other Network Rail functions on earthworks asset;

e) surface water/groundwater;

f) impact of outside party activities and assets (including natural slopes);

g) vegetation (including on clay embankments);

h) increase in track loading;

i) geological solution features;

j) animal burrowing;

k) underlying ground conditions;

l) climate change including future weather patterns and changing sea levels;

m) rock mass characteristics including inadequate legacy earthworks;

n) root jacking;

o) weathering/softening of rock including asset degradation;

p) damage caused by third-party activities; and

q) rise in regional groundwater level.