scope:

This modules covers:

a) the process for the implementation of appropriate vegetation management strategies for Earthworks in accordance with NR/L2/CIV/086;

b) Earthworks where vegetation management is required to promote earthwork stability.

NOTE NR/L2/OTK/5201 provides requirements for management of vegetation.

Many of the principles set out in this guidance note may be applied to embankments and cuttings of less than 3m height which are not defined as Earthworks in NR/L2/CIV/086.

This module does not cover:

a) operational health and safety requirements;

NOTE The safety of site operatives should be taken into account when planning vegetation maintenance. In addition, the requirement for future vegetation maintenance activities should be considered during the design and construction of Interventions.

b) operational aspects of vegetation management;

NOTE E.g. leaf fall, signal sighting and invasive species. They are set out in NR/L2/OTK/5201.

c) Earthwork examinations and vegetation inspections;

NOTE They are set out in NR/L3/CIV/065 and NR/L2/OTK/5201 respectively.

d) Earthworks that have been strengthened by repair interventions;

e) policy requirements for the management of lineside assets.

NOTE They are set out in the Lineside Asset Management Policy(Network Rail, 2017).

Purpose

This module provides guidance to earthwork managers on the implementation of vegetation management strategies for Network Rail Earthworks with regard to slope stability.

There may be instances where the presence of vegetation on an earthwork is beneficial from a geotechnical engineering point of view; however, operational requirements may be impacted by the presence of vegetation, e.g. signal sighting or overhead line encroachment. In these cases the Earthworks Manager will need to consider slope stability issues driven by tree management and manage the risks to the asset accordingly.

It allows earthwork managers to:

a) manage operational risk; and

b) control or mitigate the presence or absence of vegetation affecting:

1) soil cutting or embankment stability;

2) drainage capability or capacity on earthworks;

3) dislodged rocks falling on the track or outside party land;

4) scour of embankment toes.

NOTE An example is in figure 8.

Responsible management of vegetation on earthworks:

a) improves asset management decisions across the portfolio;

b) manages risk to stakeholders and outside parties; and

c) can enhance the overall environment of slopes.