Effects of alignment on C construction and use cts of alignment on CO2 emissions from the ...

338 Pages·2012·7.53 MB·English

University of Cambridge
Department of Engineering

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infrastructure

Lynsay Hughes
Homerton College

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January 2012

Acknowledgements
This research was made possible through the EPSRC and Arup, and I am grateful for the financial
support of both and the willingness of Arup to allow me to undertake it.
I was initially introduced to the possibility of doing a PhD through Duncan Nicholson, who was looking
for a suitable candidate within Arup. I am grateful that Duncan thought I was sufficiently suitable and
was, and still am, enormously appreciative of the help he has provided to ensure that I was able to
manage whilst undertaking the research. I am also tremendously grateful for the time of Heleni
Pantelidou over the last few years; her ongoing interest in the sustainability agenda has never waned
despite it being a seemingly uphill struggle. Her style and enthusiasm are extremely inspirational to
many ladies in Arup. The final member of the Arup Geotechnics team that I would like to express my
appreciation for is Tim Chapman who, although I only got to know towards the end of my research,
successfully and timely pulled me back from the detail to see the bigger picture. Tim’s excitement and
zest for the subject most certainly refreshed and bolstered my own.
The time of Niall Fraser, Alex Kidd and Alan Phear was both extremely valuable and greatly
appreciated.
Going back to the beginning, I would like to thank Stuart Watkins for the pioneering and original
approach he takes to his work. His bullishness and determination ensured the project that initiated
this research happened. I must also recognise the ingenuity of Chris Dales on this project. Thank you
also to Roger Milburn who casually and inventively suggested the research topic at an opportune
moment.
Thank you to my friend Stephen Finnegan who has always been at the other end of the ‘phone to
calm me in the moments of panic. I am always impressed by his self-belief and aplomb, and am glad
that some of this transferred to me during the few years we worked together. Steve encouraged me to
contact Duncan with his brilliant ‘what’s the worst that can happen?’ attitude.
Kenichi Soga, my supervisor, has supported my research and has always shown great enthusiasm
irrespective of it not being his area of expertise. I have been privileged to have been one of his
students.
My sincere appreciation goes to my advisor, Peter Guthrie, whose help and support has extended far
beyond his remit. Peter’s continual words of praise and encouragement have motivated me
throughout this research and his sage and down-to-earth approach to academic work has helped me
immeasurably.
Thank you to my family and friends. And finally, but by no means least, a heart-felt thank you goes to
Rick for simply being himself.
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Declaration

This thesis is my own work and contains nothing which is the outcome of work done in collaboration
with others, except where specifically indicated in the text. It has not been previously submitted, in
part or whole, to any university or institution for any degree, diploma or other qualification. This thesis
is less than 65,000 words in length including footnotes, tables, figures, appendices, and the
bibliography, and contains less than 150 figures.

Lynsay Hughes
January 2012
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Abstract
The environmental aspect of sustainability is currently high on many agendas due at least in part to
the issue of climate change, manifesting in the monitoring of CO emissions from all activities within
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all industrial sectors, with construction projects being no exception.
The concept of Whole Life Carbon (WLC) involves understanding the carbon impact of an
infrastructure project from its beginning, through its serviceable life, to the end of its life. The WLC
concept can be applied to future infrastructure projects to assist in decision making, to ensure the
correct project is taken forward in terms of minimising carbon emissions across the life time of the
infrastructure.
The life cycle of a highway project comprises the planning, design, construction, operation, use and
decommissioning phases. For a new 23km motorway project in the UK, when considering the
construction and use phases, the CO emissions from vehicles using the road comprised 91% over a
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40 year period. With the majority of CO resulting from the use phase, any measures taken to
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minimise the impacts of this could potentially significantly reduce the CO over the lifetime of a
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highway.
It is during the planning stage that decisions can be made to reduce the WLC; by forecasting the
impact of different design options at the different future phases of the life cycle. This thesis considers
the effect of highway alignment, which is a decision taken early in a project’s life cycle.
The gradient of a highway can have a significant impact on the fuel consumption (and hence CO
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emissions) of the vehicles operating on it. To design the alignment around an optimum earthworks
phase in terms of time, cost and carbon may result in a construction phase with a lower impact, yet
the long term effect of the subsequent gradients on vehicle fuel consumption may yield a significantly
higher level of CO emissions than the amount saved during the efficient construction operation.
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Conversely, an intensive earthworks operation may result in a CO intensive construction phase yet
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result in long term benefits throughout the life cycle, as the fuel consumed by the vehicles operating
on the highway is reduced.
To understand the effect of the vertical alignment through the life cycle, the CO in both the
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construction and use phases has been calculated. A methodology to calculate the CO from the
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earthworks operations has been developed. The instantaneous emission model, PHEM, has been
used to calculate the CO from the vehicles using a highway.
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Different vehicle types have been assessed over hypothetical terrains, with the application of varying
fleet mixes and vehicle speeds enabling an understanding of the effect of alignment on typical vehicle
flows. These alignments have been modified, requiring more CO intensive earthworks operations, to
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understand the potential benefits the new alignment can bring to the use phase, and the overall life
cycle.
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The methodology developed has been applied to an actual case study that had six very different
horizontal and vertical alignments. A second real and current project was used to gain an
understanding of the CO impacts of choosing an embankment over a viaduct structure.
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Contents
Acknowledgements i
Declaration iii
Abstract v
Contents vii
List of Appendices xiii
List of figures xv
List of tables xxiii
List of photographs xxv
Glossary xxvii
Chapter 1 Introduction 1
1.1 Sustainable infrastructure 1
1.2 Low carbon infrastructure 2
1.3 Whole life carbon 5
1.4 Low carbon highway infrastructure 6
1.5 Focus of research 7
1.6 Aim of research 8
1.7 Thesis structure 9
Chapter 2 Background study: New motorway project 11
2.1 Introduction 11
2.1.1 Project history 11
2.1.2 Scope of assessment 11
2.2 CO assessment of the construction phase 12
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2.2.1 Earthworks 12
2.2.2 CO from the structures 15
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2.2.3 CO from the road pavement 17
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2.2.4 Construction CO summary 18
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2.3 CO assessment of the use phase 19
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2.3.1 Average speed emission modelling 19
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2.3.2 Instantaneous emission modelling 21
2.4 Discussion of results 22
2.5 Conclusions 24
Chapter 3 Approach to research 27
3.1 Research motivation 27
3.2 Research aim 28
3.3 Research 28
3.3.1 The research process 28
3.3.2 Research paradigms 29
3.4 Research methodology 31
3.4.1 Positioning the research 31
3.4.2 Focussing the research 31
3.4.3 Data sources and analysis 32
3.4.4 Use of case studies 32
3.5 Experimental design 32
3.5.1 Earthworks 33
3.5.2 Hypothetical terrains and alignments 33
3.5.3 Study boundaries 35
3.5.4 Greenhouse gas emissions considered 36
Chapter 4 Review of current models and approaches 37
4.1 Introduction 37
4.2 Sustainability terminology 37
4.2.1 Life cycle assessment 37
4.2.2 Embodied energy (EE) 38
4.3 Sustainability of highway projects 40
4.3.1 LCA of highway construction 41
4.3.2 Geotechnical aspects of highway construction 44
4.4 Previous gradient research 45
4.4.1 Parry and Potter (1995) 46
4.4.2 Hillier et al. (2005) 47
4.4.3 Butler (2006) 48
4.4.3.1 Construction energy 50
4.4.3.2 Use energy 50
4.4.3.3 Approach to modelling 51
4.4.3.4 Results and analysis 53
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