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Managing the extent of tree removal from railway earthwork slopes

Managing the extent of tree removal from railway earthwork slopes
Managing the extent of tree removal from railway earthwork slopes
Trees cover the slopes of many earthworks (embankments and cuttings) supporting the UK’s rail network. Trees provide ecological and slope stability benefits to earthwork slopes but they can also cause seasonal shrinking and swelling of the soil. Seasonal shrink-swell movement in earthworks can affect the level and alignment of the track, causing delays for rail passengers and a substantial cost for infrastructure owners. Guidance is required to identify and manage the removal of problematic trees, while avoiding full tree clearance on earthworks slopes.

A study was undertaken on behalf of London Underground Ltd (LUL) to assess whether the National House Building Council (NHBC) guidance, considering tree species and the ratio of the distance of the tree from the track, D, to the mature tree height H, might be applicable to trees located on railway earthwork slopes. Excessive seasonal track movement was shown to correlate with the presence of high water demand (HWD) tree species located within a certain D/H ratio of the track, but not other tree species.

Soil heave was measured on the slope of an instrumented railway embankment following removal of trees from the embankment slope. The rate and magnitude of soil heave was estimated from five years of pore water pressure data, using a one dimensional settlement/heave calculation based on a linear swelling index. It was found that while the removal of HWD trees reduced seasonal shrink-swell movement, soil heave and upward track movement continued for at least 4 years after tree felling.
0925-8574
690-696
Briggs, K.M.
8974f7ce-2757-4481-9dbc-07510b416de4
Smethurst, J.A.
8f30880b-af07-4cc5-a0fe-a73f3dc30ab5
Powrie, W.
600c3f02-00f8-4486-ae4b-b4fc8ec77c3c
O'Brien, A.S.
d88d5bd9-31ba-41e4-86f5-c4a6e2536f39
Butcher, D.J.E.
fbf4b3d6-4f6e-4763-ae5b-bb6116bdb6c4
Briggs, K.M.
8974f7ce-2757-4481-9dbc-07510b416de4
Smethurst, J.A.
8f30880b-af07-4cc5-a0fe-a73f3dc30ab5
Powrie, W.
600c3f02-00f8-4486-ae4b-b4fc8ec77c3c
O'Brien, A.S.
d88d5bd9-31ba-41e4-86f5-c4a6e2536f39
Butcher, D.J.E.
fbf4b3d6-4f6e-4763-ae5b-bb6116bdb6c4

Briggs, K.M., Smethurst, J.A., Powrie, W., O'Brien, A.S. and Butcher, D.J.E. (2013) Managing the extent of tree removal from railway earthwork slopes. Ecological Engineering, 61 (Part C), 690-696. (doi:10.1016/j.ecoleng.2012.12.076).

Record type: Article

Abstract

Trees cover the slopes of many earthworks (embankments and cuttings) supporting the UK’s rail network. Trees provide ecological and slope stability benefits to earthwork slopes but they can also cause seasonal shrinking and swelling of the soil. Seasonal shrink-swell movement in earthworks can affect the level and alignment of the track, causing delays for rail passengers and a substantial cost for infrastructure owners. Guidance is required to identify and manage the removal of problematic trees, while avoiding full tree clearance on earthworks slopes.

A study was undertaken on behalf of London Underground Ltd (LUL) to assess whether the National House Building Council (NHBC) guidance, considering tree species and the ratio of the distance of the tree from the track, D, to the mature tree height H, might be applicable to trees located on railway earthwork slopes. Excessive seasonal track movement was shown to correlate with the presence of high water demand (HWD) tree species located within a certain D/H ratio of the track, but not other tree species.

Soil heave was measured on the slope of an instrumented railway embankment following removal of trees from the embankment slope. The rate and magnitude of soil heave was estimated from five years of pore water pressure data, using a one dimensional settlement/heave calculation based on a linear swelling index. It was found that while the removal of HWD trees reduced seasonal shrink-swell movement, soil heave and upward track movement continued for at least 4 years after tree felling.

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More information

Submitted date: 13 September 2012
Accepted/In Press date: 3 December 2012
e-pub ahead of print date: 10 January 2013
Organisations: Infrastructure Group

Identifiers

Local EPrints ID: 344689
URI: http://eprints.soton.ac.uk/id/eprint/344689
ISSN: 0925-8574
PURE UUID: c3768b9f-b3da-4bda-8291-483cbb1283c8
ORCID for K.M. Briggs: ORCID iD orcid.org/0000-0003-1738-9692
ORCID for J.A. Smethurst: ORCID iD orcid.org/0000-0001-8175-985X
ORCID for W. Powrie: ORCID iD orcid.org/0000-0002-2271-0826

Catalogue record

Date deposited: 02 Nov 2012 16:19
Last modified: 12 Aug 2024 01:36

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Contributors

Author: K.M. Briggs ORCID iD
Author: J.A. Smethurst ORCID iD
Author: W. Powrie ORCID iD
Author: A.S. O'Brien
Author: D.J.E. Butcher

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