.
I
1
Department for
Transport
Sustainable Highways:
AShortGuide
,Iqr
rAr
UK ROADS BOARD
June 2008
Department for
Transport
Sustainable Highways:
A Short Guide
J M Reid, J W E Chandler, I Schiavi and A P Hewitt (TRL Limited)
June 2008
London: TSO
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Printed in Great Britain on paper containing at least 75% recycled fibre.
Contents
I.
Introduction
5
2.
Sustainable construction
6
3.
Linking to corporate objectives
8
4.
How to build a sustainable road
9
5.
Materials, methods and milestones
13
6.
Key performance indicators and sustainability index
20
7.
Specifications and quality control
22
8.
Environmental impacts
26
9.
Waste management regulations
27
10. Measuring sustainability
11.
Climate change
30
35
12. Conclusions
36
References
37
Useful websites
39
CHAPTER 1
Introduction
This document provides succinct guidance for local authority highway and
material engineers on the choice of sustainable materials and techniques for
use in highway and footway maintenance as well as new construction. It is a
daughter document to Wellmaintained Highways: Code of Practice for Highway
Maintenance Management' and is applicable throughout the UK. Further details
and case studies are given in a separate, more comprehensive document.*
Local authorities are responsible for some 98 per cent of the road network in
England and Wales as well as similar amounts in Scotland and Northern
Ireland. This includes a very wide range of roads, from heavily trafficked
principal roads to very lightly trafficked rural lanes and suburban estate roads.
The maintenance of this asset, and 'construction of new roads and footways,
have major sustainability impacts, and the choice of materials and methods
can have a significant effect on these impacts. This document provides
guidance for local authority highway and material engineers on sustainable
choices of materials and methods for their works.
The comprehensive document mentioned above contains detailed descriptions
of the sustainable materials and methods available for highway maintenance
and a number of case studies. It has been published separately by TRL.2
Previous page
is blank
CHAPTER 2
Sustainable construction
Sustainable development has been defined as “development that meets
the needs of the present without compromising the ability of future
generations to meet their own need^".^ It has been incorporated in UK
government policy for a decade, initially through the UK strategy for
sustainable de~elopment,~
followed by the UK strategy for sustainable
constr~ction.~
The latter was reviewed in 2006, and an updated strategy
was published in 2008. This is available at www.berr.g0v.uk. The UK
national sustainable development strategy was renewed in 2005,6and the
devolved administrations have developed their own regional sustainability
strategies that mirror the four priority areas of the UK national strategy:
sustainable consumption and production;
EI climate change and energy;
EI natural resource protection and environmental enhancement; and
sustainable communities.
Highway maintenance and new construction have a direct effect on these
priority areas:
E
FI
EI
They consume large quantities of construction materials and generate large
quantities of waste.
The extraction, processing and transporting of these materials is a
significant source of greenhouse gas emissions, particularly in the
production of cement and asphalt.
Use of primary aggregates in preference to recycled or secondary
aggregates results in depletion of irreplaceable natural resources and
damage to the environment where the aggregates are located.
Incorrect use of materials can result in pollution of the environment.
For highway maintenance and construction to be sustainable, there
must be a focus on recycling arisings from the existing road wherever
possible, using imported recycled or secondary aggregates where
appropriate, and choosing techniques that minimise the production of
greenhouse gases. These principles are in line with the waste hierarchy
(Figure 2.1) that underlies all UK and European legislation on waste:
BI
6
Reduce the levels of waste produced.
Reuse products wherever possible.
Recycle what cannot be reused.
Recover energy from waste that cannot be reused or recycled.
Dispose of materials only as a last resort.
Chapter 2 Sustainable construction
Local authority highway engineers and their partners are crucial to achieving
sustainability in highway maintenance and construction by making informed
choices about the materials and techniques that they employ. Sustainability in
highway maintenance and construction means living within our environmental
limits while achieving a sustainable economy.
Figure 2.1 The waste hierarchy
7
.
CHAPTER 3
Linking to corporate objectives
Local authorities have been quick to respond to government policy on
sustainability, and most now include references to sustainability in their
corporate objectives. This is often implemented in areas such as kerbside
recycling, other waste collection initiatives, use of recycled paper and reducing
waste in the authority’s own offices. However, the link to activities such as
highway maintenance is not always made. This requires a clear lead from
senior management and the establishment of policies that translate these
objectives into action. It is vital that these objectives are cascaded down and
incorporated into the aims of all departments to ensure a common approach
across the organisation.
By making a link to corporate objectives, a focus can be brought on the whole
process of highway maintenance, which allows sustainability to influence this
process, rather than trying to tack it on at the end. The choice of materials
. and techniques can then be looked at logically in this overall context, as part
of the process, and much greater changes can be achieved as a result.
Hampshire County Council included “stewardship of the environment” as
one of its six corporate objectives. This was fed down through the Highways
Policy Document, which outlined what this meant for highway maintenance,
and how these factors should be taken into account whenever designing
a maintenance scheme or planning a maintenance operation.
(www.hants.gov.ukJ
Durham County Council included “looking after the environment” as one
of its five corporate aims. This aim has three objectives, one of which is
“To manage waste and resources sustainably, reduce pollution and adapt
to climate change”. This has been cascaded into a number of council
documents, including “Building in Sustainability”, which contains checklists
for all who are involved in design and construction processes. The document
states that, in the development of new road maintenance schemes, the
potential for in-situ recycling and the use of secondarylrecycled materials
should be assessed. An example of how this was applied on the A689
Sedgefield to Wynyard Improvement is given. (www.durham.gov.uk)
8
Chapter 4 How to build a sustainable road
CHAPTER 4
How to build a sustainable road
Making sustainable choices about materials for highway and footway
maintenance and new construction is not something that should be done in
isolation or on an opportunistic basis. This will result in limited improvements
and will run up against barriers, both technical and non-technical. However,
specific technical solutions (given in Chapter 5) are only one part of the
process. The key steps of incorporating sustainability into highway
maintenance are described in Figure 4.1.
Step I:Get support from the top
If the senior officers and elected members can see the benefits and approve
the strategy, there is much more opportunity for making significant changes.
Recycling is in tune with public concerns and expectations, so is something
that most local authorities will be keen to promote to demonstrate their
commitment to sustainability.
Figure 4.1 How to incorporatesustainability into highway maintenance
tep 5: Liaise with other departments in your council.
have logistic support for recycling.
rtnsOgy*-
te Key Performance Indicators.
Step 11: Keep track of materials.
Step 13: Monitor progress.
-
Step 14: Aim for continual improvement.
Step 15: Celebrate success.
9
I
I
Sustainainable Highways: A Short Guide
Step 2: Get all the key players involved at an early stage
Getting buy-in from all parties will generate more ideas and make it easier to
implement them.
Step 3: Appoint a champion
It may be helpful to appoint an individual to head up sustainability within
the highways department and ensure liaison between all internal and
external stakeholders.
Step 4: Assess what is appropriate for your area
Learn from the experience of neighbouring local authorities and bodies such
as the Highways Agency who may be carrying out relevant works in or near
your area. This may involve making a quantitative assessment of likely arisings
from your own highway and footway works and the availability of recycled,
secondary and primary aggregates in the area. Tools are available to help you
decide which options are likely to be the most sustainable for your situation
(Chapter 10).
Step 5: Liaise with other departments in your council
The Planning Department will have information on sources of primary
aggregates and recycling facilities for other materials. Parks and Countryside
Departments may be carrying out small-scale works and may either be
able to supply materials from their works or use surplus materials from
yours. Departments such as Estates, Waste and Education may be
constructing access roads and car parks for various facilities, and these
provide opportunities for using sustainable materials and techniques.
Liaise with the local Environment Agency office as necessary.
Step 6: Ensure you have logistic support for recycling
Recycling does not happen in a vacuum. Facilities are required where
surplus materials and arisings from highway works can be stored and
processed. It is important that different types of arisings are segregated
so that maximum value can be obtained from them, so keep subsoil,
asphalt and concrete separate. Strategically located recycling facilities
are required, and these will need appropriate planning permission and
waste management licences or exemptions. Senior officers, elected
members and the Planning Department must understand the need for
these facilities and be willing to support new ones where necessary.
10
I
Chapter 4 How to build a sustainable road
Step 7: Develop a procurement strategy to
encourage sustainability
The methods of procurement used for local authority highway works,
particularly for relatively long-term maintenance contracts, can have a major
effect on the extent to which sustainable practices can be implemented. It is
important to have sustainability objectives and key performance indicators
(KPls) written into the contract. WRAP7 have produced a very useful stepby-step guide to local authority procurement for highway maintenance,
entitled Recycled Roads; this is available at www.aggregain.0rg.uk.
Step 8: Do not be afraid to use primary aggregates
The source of materials with the least transport distance to the works will
generally be the most sustainable. This may be local sands, gravels or rocks,
especially in many rural areas, or locally available secondary aggregates. In
some situations, use of new materials will be the only feasible engineering option.
Step 9: Set appropriate key performance indicators
(KPls) (see Chapter 6)
KPls should be selected with care to be relevant, easy to measure and, if
possible, use information that is already being recorded. The number of KPls
should be limited to avoid confusion.
Step 10: Insist on quality control from suppliers
Concern about the variability and durability of recycled and secondary
aggregates has been one of the main factors inhibiting the use of these
materials. Most specifications permit the use of recycled and secondary
materials, provided they are produced in accordance with an appropriate
quality control scheme (Chapter 7), such as the WRAP QualitybProtocols for
the production of aggregates from inert waste (at www.aggregain.org.uk).
Step 11: Keep track of materials
Arisings from highway works should be regarded as a resource, not a
waste. Aim to reuse them on site or, if that is not possible, ensure that they
are sent for recycling or used on other sites in your programme of works.
Step 12: Create a sustainability culture throughout the
supply chain
In particular, encourage the people at the sharp end who have to carry out
the work or inspect it. Be open to suggestions for ways to make things work
better on the ground, so that it is not just something imposed from above.
11
Sustainainable Highways: A Short Guide
Step 13: Monitor progress
Set up systems so that progress towards targets is monitored and reported to
all parties involved in the works, not just senior management. This will help to
encourage buy-in from all stakeholders.
Step 14: Aim for continual improvement
This can be done by setting targets for year-on-year increases in recycling
or decreases in materials sent to landfill. These targets must be realistic.
After a few years the ‘quick wins’ will be exhausted and more fundamental
changes may be required. Plan for these, and involve key stakeholders
at an early stage, so that an appropriate strategy can be developed.
Step 15: Celebrate success
Ensure that everyone is congratulated when targets are met, and spread the
word through the rest of the council and industry. This will encourage greater
commitment from the workforce, keep senior management happy and persuade
other councils to follow your example.
I
CHAPTER 5
Materials, methods and milestones
In general terms, the sustainable choices of materials for highway works
should be in the following order of priority:
1
reuse existing highway materials at the same level or at as high a level as
reasonably practicable;
2
use imported recycled or secondary materials as much as
reasonably practicable;
3 use primary materials.
Methods should be chosen which enable this order of priority to be achieved,
e.g. use of in-situ or ex-situ cold recycling of pavements in preference to
reconstruction with primary materials, or use of lime or cement to stabilise soils
in situ in preference to excavation and replacement with imported granular
materials for capping or subbase.
To help in assessing the degree of sustainability that has been achieved in a
scheme, a series of milestones have been developed. The higher the
milestone number, the greater the overall sustainability of the scheme and the
greater the effort that will be required to achieve it. The milestones are
cumulative, so that Milestone 2 includes the measures in Milestone 1 and so
on. They are defined below:
Milestone 0 is use of standard techniques for highway maintenance that are
safe and fit for purpose but do not include any use of recycled or secondary
materials.
Milestone 1 is use of the same techniques as Milestone 0 but with substitution
of recycled or secondary materials for primary materials in low-risk applications,
e.g. unbound applications and footwayskycle tracks. It also includes use of
recycling techniques that are well established and low risk, such as cold recycling
of pavements and footways.
Milestone 2 encompasses Milestone 1 and also includes use of innovative
techniques and materials that permit use of recycled or secondary materials in
higher-value applications but are less commonly used than those in Milestone 1,
e.g. high levels of reclaimed asphalt in new hot asphalt, use of recycled
aggregate in low-strength ancillary concrete or use of hydraulically-bound
materials (HBM) with binders other than cement for subbase.
13
Sustainainable Highways: A Short Guide
Milestone 3 encompasses Milestones 1 and 2 and also includes use of
innovative techniques and materials that are relatively new and/or require
specialist contractors and/or designers; these are slightly higher-risk than
conventional techniques but permit use of recycled or secondary materials in
high-value applications, e.g. use of hydraulically-bound materials with binders
other than cement in the base course or recycling of surface course into new
surface course.
The intention is that local authorities would progress from Milestone 0 to
Milestone 3 as they gain more experience and confidence in working with
recycled and secondary materials. The milestones should be achieved in the
order shown. However, this does not preclude progressing some actions in
Milestone 3 before Milestone 2 is fully achieved. Progressing Milestone 2
and 3 actions should not delay achievement of Milestone 1, which should be
completed as a matter of urgency.
The work undertaken in construction and maintenance of highway works
has been divided into six applications. For each application, a number of
actions are grouped under the four milestones. The actions include the use
of different materials and maintenance techniques as well as the production
and reuse of waste. The actions under each milestone vary among the
applications, reflecting the relative ease with which they can be accomplished.
Surfacing
Description of works:
surface dressing;
slurry surfacing;
inlay and overlay;
replacement or renewal of surface course;
new surface course.
I
0
Use primary aggregates and hot asphalt for all applications.
Dispose of arisings to landfill or exempt site.
in-situ hot recycling using the repave or remix processes.
Use materials such as steel slag, if it is available, economic and
meets requirements.
Recycle arisings as unbound subbase or capping.
Retexture surfacing to avoid having to replace it.
In-situ cold recycling using the retread process.
Recycle arisings into new surface course at 10 per cent.
Collect surface dressing sweepings and surplus and reuse in new
surface dressing.
Recycle arisings into new surface course at >I0 per cent.
Recycle thin surfacing into new thin surfacing.
14
Chapter 5 Materials, methods and milestones
Pavement reconstruction
Description of works:
reconstruction of structural (base and binder) course of pavement;
construction of new base and binder course.
0
Use primary aggregates and hot asphalt or concrete for all
applications.
Dispose of arisings to landfill or an exempt site.
1
Cold in-situ or ex-situ recycling of existing bituminous or concrete
pavement .
Use up to 30 per cent reclaimed asphalt in new hot asphalt.
Recycle arisings as unbound subbase or capping.
2
Use greater than 30 per cent reclaimed asphalt in new hot asphalt.
Use recycled or secondary aggregates in new hot asphalt if it is
available, economic and meets requirements.
Use crack and seal for concrete pavements.
Use saw cut and seal for bituminous overlays on concrete
pavements.
3
Use HBMs with binders other than cement (e.g. pulverised fuel ash
or slag) as a combined base and subbase with recycled
aggregates. Improved foundations using HBMs may allow reduction
in thickness of upper layers.
Use recycled or secondary aggregates in new pavement quality
concrete if it is available, economic and meets requirements.
Separate surface course during planing or break-out and recycle in
new surface course.
15
Sustainainable Highways A Short Guide
Edges
Description of works:
repairs to existing verges and haunches (rural roads);
haunching to widen rural roads;
repairsheplacements to verges, kerbs and drainage.
0
Use primary aggregates/concrete/hot asphalt for all applications.
Dispose of arisings to landfill or exempt sites.
Use recycled aggregates (e.g. planings) for unbound applications.
Send arisings to recycling centre.
Use lime or cement to stabilise existing soils and avoid need for
imported capping.
Use up to 30 per cent reclaimed asphalt in new hot asphalt.
Use recycled aggregates in ancillary concrete for kerb bedding and
backing.
Use lightweight kerbs.
Segregate arisings on site into asphalt, concrete and soil and send
to recycling centre for higher-value applications.
~~
3
_ _ _ _ _ _
Use lime andlor hydraulic binders to stabilise existing soils and
avoid need for imported subbase and base.
Use greater than 30 per cent reclaimed asphalt in new hot asphalt.
Use recycled or secondary aggregates in new hot asphalt if
available, economic and meet requirements.
Use recycled or secondary aggregates in new pavement quality
concrete if available, economic and meet requirements.
Use reclaimed bricks to support gullies and manholes.
16
Chapter 5 Materials, methods and milestones
Footways and cycle tracks
Description of works:
repairs to existing footways and cycle tracks;
construction of new footways and cycle tracks.
0
Use primary materials and hot asphalt for all applications.
Dispose of arisinas to landfill, exempt sites or farmers’ tracks.
1
Use cold recycled bitumen bound material for repairs to existing
footways for subbase, base and binder course.
Use recycled aggregates as unbound subbase.
Send arisings to recycling centre for use in other repairs as cold
recycled bitumen bound material - closed loop system.
2
Use quarry fines for repairs and new construction of surfacing for
footpaths and cycle tracks where these are locally available and
environmentally appropriate. Add cement where necessary.
On-site hot recycling of asphalt footways into new hot asphalt using
mobile plant.
Use lime and/or hydraulic binders to treat weak subgrade materials
rather than excavate and replace with imported granular materials.
3
Use lime and/or hydraulic binders to treat existing soils and avoid
need for imported subbase and base.
17
Sustainainable Highways: A Short Guide
Capping and subbase
Description of works:
repairs to existing capping and subbase;
capping and sub-base in new construction.
1
Use primary aggregates for all applications.
Dispose of arisings to landfill or exempt sites.
2
Use recycled aggregates for unbound applications.
Send arisings to recycling centre.
Incorporate some of existing subbase in full-depth cold recycling of
existing pavement .
2
Use lime and/or cement to stabilise existing soils and avoid need
for imported capping (beware of sulfates/sulfides).
Segregate arisings on site into asphalt, concrete and soil and send
to recycling centre for higher-value applications.
Replace subbase with HBMs (other than cement).
3
Use lime and/or cement to stabilise existing soils and avoid need
for imported subbase (beware of sulfates/sulfides).
Use HBMs (other than cement) as a combined base and sub-base
with recycled aggregates and secondary binders.
18
Chapter 5 Materials, methods and milestones
Earthworks
Description of works:
rn repairs to slope failures in existing embankments and cuttings;
treatment of weak subgrade in existing or new construction;
construction of new embankments and cuttings.
0
Use imported primary aggregates for repairs to slope failures or
weak subgrade.
Reuse material excavated from cuttings in embankments where
possible and attempt to balance earthworks.
Dispose of surplus arisings or unsuitable material to landfill or
exempt sites .
1
Use recycled or secondary aggregates for repairs to slope failures
or weak subgrade where these are available and cheaper than
primary aggregates.
If it is necessary to import fill (e.g. for road widening), use recycled
or secondary aggregates where possible.
Use lime andlor hydraulic binders to improve weak material from
cuttings for use as general fill if this is economic.
2
Use lime and/or hydraulic binders to stabilise weak subgrade rather
than excavating and replacing with granular material.
Use lime and/or hydraulic binders and geosynthetics to repair slope
failures in clay soils reusing the failed material on site.
Use recycled or secondary aggregates for ground improvement to
weak subgrade, e.g. stone columns.
3
Use lightweight aggregate, such as pulverised fuel ash, expanded
polystyrene, expanded clay or tyre bales, for earthworks over deep
weak subgrade to limit settlement.
19
CHAPTER 6
Key performance indicators
and sustainability index
It is important that highways departments set their targets and KPls at the right
level, to realise continuous improvement in sustainability performance. Ideally,
existing KPls and targets measured for other internal reporting schemes should
be used first, to avoid duplicating effort and ensure better use of resources.
Where possible, it is useful to consult the contractors and/or the overall supply
chain to understand which indicators they might already use for corporate
reporting, for other clients or for industry schemes (e.g. Constructing
ExceIIence, QPA).
The amount of recycling is often used as a key performance indicator (KPI) for
projects, because it can be measured relatively easily, but it does not necessarily
equate to an absolute measure of sustainability. Much depends on what level the
materials are recycled at, and the overall transport distances and energy use
of the work as a whole. A series of milestones were therefore set up for KPls in
the same way as the milestones for different applications (Chapter 5).
It is best to concentrate on just a few KPls and targets in order to avoid adding
too much to the existing number of indicators. Different levels of KPls can be
used for different applications, taking into considerations the associated risks,
so that a local authority Highways Department might decide to set Milestone
3 targets and KPls for footways and cycle tracks but use Milestone 1 for
surfacing. It might be advisable to use KPls at a certain milestone for a few
years, but raise the targets to the maximum achievable within that milestone
until confidence has built up to make a step change to the next milestone.
Milestones with a ‘score’ from 0 to 3 can therefore be set for seven activities,
the six applications in highway works and the KPls. The milestone ‘scores’
for the six applications and the KPls can be used to calculate an overall
sustainability index by summing the ‘scores’ of the milestones for all
seven activities. Thus, if the council was at Milestone 3 for all applications
and the KPls, the maximum possible score would be 21. The score for
each application and the KPls should reflect the average for all works,
not the best one or two projects, and should be independently audited to
ensure that it reflects the real position. Milestone 0 for the KPls is important,
because some local authorities may be carrying out recycling and scoring
well on the application milestones, but are not keeping any records and,
hence, are unable to prove the level of recycling they are achieving.
20
Chapter 6 Key performance indicators and sustainability index
The sustainability index provides a simple indicator of how a local authority is
performing in terms of sustainability in highway works. It can usefully be included
in corporate aims for local authorities, e.g. ‘to be at Milestone 3 in all applications
and KPls by 2010’.
Key performance indicators
Description of works:
rn KPls and targets for sustainability in highway maintenance and new
construct ion works.
0
No recycling carried out, or
recycling not recorded.
No formal system for recording
amount of recycling or diversion
of waste from landfill.
1
Percentage of waste sent
for recycling.
E.g. up to 100 per cent of all
bituminous bound arisings.
Percentage of waste sent
to landfill.
In line with overall targets for the
local authority.
Percentage of recycled materials
used (by volume or value), overall
or in specific applications.
Baseline values or minimum/low
risk accepted within standard
specifications.
Cost savings due to recycling.
Positive (i.e. cost savings rather
than losses).
~
2
3
~~
Percentage of waste recycled
on site.
Project-specific, taking into
account industry good practice.
Percentage of imported recycled
materials (by volume or value).
Relate to available material
on site.
Percentage of work for which
recycling is specified (i.e.
required, not optional).
The Office of Government
Commerce advises setting 10
per cent (by value) as a minimum,
but work undertaken by WRAP
has demonstrated that higher
values can be achieved.
Percentage of recycled materials
used (by volume or value), overall
or in specific applications.
Incrementally increased
from baseline and/or industry
good practice.
Reduction in construction waste.
Project-specific, taking into
account industry best practice.
Percentage of recycled materials
used (by volume or value), overall
or in specific applications.
Incrementally increased from
Level 2 and/or industry best
practice.
Percentage of all aggregates
sourced within a specified miles/
km radius.
The maximum, considering
technical requirements (e.g. high
PSV aggregates might need to
be imported).
Savings in emissions of CO,.
Positive, i.e. savings with respect
to existing practices.
21
CHAPTER 7
Specifications and quality control
One of the main reasons given for not using recycled and secondary materials
is concern about quality and durability. This is addressed by means of appropriate
specifications and quality control protocols. In the past, many specifications did
not permit the use of recycled andlor secondary materials and recycling techniques,
and some engineers appear to think that this is still the case. In fact, all the
commonly used specifications have been significantly updated over the last
ten years and most now permit the use of recycled materials and recycling
techniques, subject to meeting quality and performance requirements.
The most commonly used specification is the Specification for Highway Works
(SHW),* which is maintained jointly by the Highways Agency, Transport Scotland,
the Welsh Assembly Government and the Department for Regional Development
in Northern Ireland. The SHW is primarily aimed at the design, construction
and maintenance of trunk roads and motorways, so adhering to this regardless
of the application means that local authorities may be over-specifying materials
and not be making the best use of locally available materials. The County
Surveyors’ Society (CSS) is currently developing a Local Authority Roads
Guide to avoid potential problems of over-specification using the SHW.
The SHW and its companion document, the Notes for Guidance on the
Specification for Highway Works (NFG) form Volumes 1 and 2 of the Manual of
Contract Documents for Highway Works (MCHW).8They are updated regularly
and refer to new and updated British and European Standards, which do not
discriminate between natural, recycled and manufactured aggregates. The
SHW and NFG also include reference to relevant technical documents, such
as TRL Reports.
The SHW and NFG are supported by the Design Manual for Roads and Bridges
(DMRB),gwhich includes a collection of design (HD) and advice (HA) notes,
also maintained by the above organisations. Many of the documents in the
DMRB are relevant to sustainable use of materials in local authority highway
works, in particular:
H
Volume 4 Geotechnics and Drainage;
Volume 7 Pavement Design and Maintenance;
Volume 10 Environmental Design and Management.
Of particular importance is HD 35/04 (Vol. 7 Part
which deals with conservation
and the use of secondary and recycled materials. This includes a table,
reproduced here as Table 7.1, summarising the applications for which a range
22
Chapter 7 Specifications and quality control
of recycled and secondary materials may be used, subject to compliance with
the requirements of the SHW. This may be used as an initial guide as to
whether the materials would be suitable in local authority highway works. More
detailed information is given in the companion document to this guidance.2
Information on the use of recycled and secondary aggregates under a number
of specifications, including the SHW, is given in the Specifier section of the
AggRegain website.1° The website also contains many case studies of the
use of recycled and secondary aggregates in local authority highway works.
Further design guidance specific to Scotland is available on the AggRegain
website.ll The document reflects the desire of Transport Scotland to encourage
the use of recycled and secondary aggregates in a sustainable manner and to
reduce the demand for primary aggregate extraction. The guidance is based
on TRL Reports 61112and 61513and introduces the concept of performance
specifications based on analytical design techniques. This guidance could
equally well be used by other local authorities as a way of introducing new
concepts that encourage recycling and sustainable construction methods into
their own specifications.
Another widely used specification in England and Wales is the Specification for
the Reinstatement of Openings in Highways.14In Scotland and Northern
Ireland, the equivalent document is the Specification for the Reinstatement of
Openings in Roads.15The documents permit the use of alternative materials
and techniques, provided that specified performance criteria, such as settlement,
are met. However, approval from the local authority is required for any alternative
materials or techniques, so the approach of the local authority is key to the
amount of recycling that is carried out.
-
Assurance about the quality of recycled and secondary materials can be given
by the use of quality protocols, which demonstrate that the supplier has
procedures in place to ensure the consistency and quality of his product. The
WRAP Quality Protocol for the production of aggregates from inert waste16 is
an example; versions of this protocol for England and Wales, Scotland and
Northern Ireland are available. This covers many of the materials likely to be
encountered in arisings from highway and footway works, including asphalt
planings, concrete, brick, soil and stones. The use of recycled aggregates
under the SHW is conditional on the supplier using the WRAP Quality Protocol.
Local authorities should make this a condition of the use of recycled
aggregates in their own highway works.
Waste protocols are currently being developed by the Environment Agency
and WRAP for a number of secondary materials that could be used in highway
works, including pulverised-fuel ash, contaminated soils and shredded or
crumbed tyres. Information on the project and an interim position statement
are available on the Environment Agency web site, www.environment-agency.
gov.uk. Local authorities should require their suppliers to use these protocols.
23
Sustainainable Highways: A Short Guide
Many suppliers of recycled and secondary aggregates, such as steel and
blastfurnace slag, pulverised-fuel ash and incinerator bottom ash aggregate,
have developed protocols for their products to ensure that they are of
consistently high quality. Many have also produced guidance on the use of
their products in road construction and other applications. Recycled and
secondary aggregates should only be used where the producer can provide
evidence of the quality and consistency of the materials.
Compost is another material that contributes to sustainability when used in
highway works. Specifications and a draft protocol for the use of compost are
available at www.wrap.org.uk/organics.
The sustainability of local authority highway works can thus be significantly
increased by the use of existing specifications and quality protocols without
any increase in risk.
Table 7.1 Specification for highway works (MCHW 1): application of
secondary and recycled aggregates (from HD 35/04)
Blastfurnace slag
Burnt colliery
spoil
China clay sand1
stent
Coal fly ash/
pulverised fuel
ash (CFA/PFA)
Foundry sand
Furnace bottom
ash (FBA)
Incinerator
bottom ash
aggregate (IBAA)
Phosphoric slag
Recycled
aggregate (RA)
Recycled asphalt
(RAP)
Recycled
concrete (RCA)
Recycled glass
24
J
J
J
J
J
J
J
x
J
J
J
J
I(
I(
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
x
J
x
x
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
I(
J
J
J
J
J
Slate aggregate
J
J
J
J
Spent oil shale
Steel slag
Unburnt colliery
spoil
I(
J
J
J
J
x
x
J
J
J
J
J
J
I(
x
J
I(
I(
J
I(
8
.
Chapter 7 Specifications and quality control
Key:
J
Specific (permitted as a constituent if the material complies with the Specification (MCHW
1) or General Provision (permitted as a constituent if the material complies with the
Specification (MCHW 1) requirements but not named within the Specification (MCHW 1)).
8
Not permitted.
important notes:
1
Table 7.1 is for guidance only and reference must be made to the accompanying text (of
HD 35/04) and the Specification (MCHW 1). Materials indicated as complying with the
Specification (MCHW 1) for a particular application may not necessarily comply with all
the requirements of the series listed, only particular clauses. For example, in the 600
Series, unburnt colliery spoil can satisfy the Specification as a general fill, but is excluded
as a structural fill; and in Series 1000 recycled or secondary materials are not permitted
within the running surface of PQ concrete. Reference should also be made to the
Specification (MCHW 1) for any maximum constituent percentages of specific recycled
or secondary aggregates. For example, in the 1000 Series, the maximum by mass
constituent of recycled asphalt is given under the limits for ‘other material’ (Table 10/2)
within the Specification (MCHW 1).
2
There is no specific or general provision for the use of recycled glass as an aggregate
in PQ concrete or hydraulically bound mixtures due to the potential for deleterious alkalisilica reaction (ASR). However, its use may be permitted by the overseeing organisation
if sufficient provisions to minimise the risk of deleterious ASR are included in the
mixture design.
3
There is no specific or general provision for the use of steel slag as an aggregate in PQ
concrete or hydraulically bound mixtures due to the potential for volume instability.
However, its use may be permitted by the overseeing organisation if sufficient assurance
of volume stability is provided.
25
CHAPTER 8
Environmental impacts
The use of recycled and secondary materials and recycling techniques results
in numerous environmental benefits, including:
U
preservation of primary aggregates;
utilisation of materials that might otherwise be disposed of to landfill;
reduction in transport distances and associated noise and congestion; and
reduction in energy use and emissions of greenhouse gases.
Tools by which these environmental benefits can be quantified are given in
Chapter 10. In most cases the environmental impacts of using recycled and
secondary materials will be similar to those for primary materials. The materials
from which recycled aggregates are produced under the WRAP Quality Prot~col,’~
for example, are classed as inert wastes and thus the recycled aggregates
produced will generally not have significant impacts on the environment. There
are some situations, however, where potential environmental impacts could
occur and where appropriate precautions need to be taken.
EI
U
rn
EI
EI
26
Coal tar, a constituent of some older asphalt mixtures, contains polycyclic
aromatic hydrocarbons (PAHs) which are liberated if the asphalt is heated,
i.e. during hot plant mixing or hot in-situ recycling. If the material is
encapsulated in a cold mix process, PAHs will not be liberated.
Hazardous materials can leach from unbound mixtures after construction
due to contact with moisture and water. However, leaching from bituminous
bound or hydraulically bound materials (including concrete) is unlikely.
For materials that contain high concentrations of potential contaminants,
such as slags, ashes and colliery spoil, a site-specific assessment of the
risks of pollution of surface and ground water may be required if the
construction is in sensitive areas, such as major aquifers or Sites of Special
Scientific Inte rest (SSSIs).
Ensure all slags and ashes are properly weathered in accordance with
quality protocols before use, and avoid use in unbound applications below
the water table.
Ensure materials are produced and used in accordance with a waste
protocol, if one is available. Many suppliers provide guidance on the use of
their materials, and this should be followed.
Liaise with the local Environment Agency officer if you have any concerns.
CHAPTER 9
Waste management regu ations
The application of the Waste Management Regulations to the use of recycled and
secondary aggregates is another area that causes much confusion. Information
on this topic is available in the Waste Management Regulations module of the
AggRegain website, www.aggregain.0rg.uk, and general information is available
at www.netregs.gov.uk and www.environment-agency.g0V.uk.
All material that is excavated during highway works has the potential to be
waste, even if it is reused on site or sent for recycling or recovery, and may be
classed as a waste and be subject to the Waste Management Regulations.
Waste is defined in the European Union Framework Directive on Waste17
(2006/12/EC) as follows: “Waste means any substance or object . . . which the
holder discards or intends or is required to discard”. The term ‘discard’ is
interpreted widely and does not just include materials that would ordinarily be
thought of as being ‘thrown away’.
The owner, producer and handler of the waste have a duty of care under the
Environmental Protection Act 1990, reinforced by the Clean Neighbourhoods
and Environment Act 2005 to ensure that the waste is handled safely and does
not present a threat to human health or the environment. This includes
ensuring that:
the waste has a transfer note identifying it using the European Waste
Catalogue (implemented through the List of Wastes Regulations 2005 in
England, Wales and Northern Ireland);
it is handled by registered waste carriers; and
it is delivered to a site that is properly licensed to treat and receive it.
/
Although the actual work will generally be carried out by subcontractors, the
local authority still has a duty of care to ensure that the waste is handled and
disposed of responsibly.
In England and Wales the Environment Agency adopts a regulatory risk-based
approach, such that activities that pose a high risk are heavily regulated and
those that pose a low risk are less heavily regulated. Local authority highway
engineers should liaise with their local Environment Agency area office to seek
advice on the need for waste controls, and to ensure the need for licences,
exemptions etc. is recognised at the early stages of any project or maintenance
programme. In Scotland, the relevant body is the Scottish Environment Protection
Agency (SEPA) and in Northern Ireland it is the Department of the
Environment for Northern Ireland.
27
Sustainainable Highways: A Short Guide
It is also important to note the difference between recycled materials and
materials that have been recovered and cease to be waste. The use of recycled
or secondary aggregates may still be subject to waste controls unless they
have been fully recovered, for example in accordance with the WRAP quality
protocol for the production of aggregates from inert waste. It is important to
check that aggregate producers who supply aggregates based on the quality
protocol are applying it properly, and not using it as a cover for waste disposal
rather than aggregate manufacture.
Waste is categorised into three classes for acceptance at landfill sites:
inert;
non- hazardous;
hazardous.
Much of the arisings from highway maintenance and construction work will
generally be classed as inert waste, e.g. asphalt planings, concrete kerbs
and pavements, subbase and capping, and subsoil. However, if the material
contains biodegradable materials such as organic matter (including topsoil),
timber, paper or material such as plastics or metals, it will be classed as
non-hazardous or ‘active’ waste. This attracts a much higher landfill tax
(f32/tonne from April 2008, rising at f8/year, compared to f2.50/tonne
for inert waste) and is much more expensive to dispose of to landfill.
Hazardous waste is not likely to be encountered in most routine highway
maintenance works, which generally only affect the near-surface layers. An
exception is the occurrence of tar in old asphalt pavements. Tar is a generic
term for a group of organic compounds produced as a by-product of the
distillation of coal to produce methane gas. It includes compounds such as
polycyclic aromatic hydrocarbons (PAHs), which are now known to be
carcinogenic, and hence it is classed as hazardous waste. Tar was widely
used in roads in place of bitumen up to the early 1970s, and may still be
encountered in old pavements when they are excavated as part of maintenance
works. It is recognised by its pungent smell. Site testing equipment using an
aerosol spray (PAC Marker) can be used to identify the presence of material
contaminated by tar; however, if more detailed quantification regarding the
level of tar present is required, samples should be sent for chemical analysis.
As a hazardous waste, tar can only be sent to landfills licensed to accept such
materials. This is very expensive, and many areas of the UK, such as Scotland
and the South East of England, now have no hazardous waste landfills. Asphalt
containing tar cannot be used in a hot recycling process, because this will
volatilise the carcinogenic compounds and put plant workers and the public at
risk. However, cold recycling techniques can be used to encapsulate the tar
compounds in a new road construction, using in-situ or ex-situ techniques. The
contaminated material is then safely stored in an engineered form where it is not
released to the environment. The County Surveyors’ Society (CSS) is producing
guidance for local authorities on how to dispose of tar-bearing materials.
28
Chapter 9 Waste management regulations
Hazardous waste may also be encountered in the form of contaminated soils,
especially in new construction on brownfield sites. The Environment Agency
and WRAP are currently producing a waste protocol for contaminated soils
(see Chapter 7). If contaminated materials (including tar) are discovered,
discussion should be held with the regulatory authorities (Environment Agency
in England and Wales, Scottish Environment Protection Agency in Scotland,
Waste Management and Contaminated Land Inspectorate of the Environment
and Heritage Service, an Agency of the Northern Ireland Department of the
Environment) at an early stage to agree a strategy for dealing with them.
29
CHAPTER I 0
Measuring sustainability
The amount of recycling is often used as a key performance indicator (KPI) for
projects, as it can be measured relatively easily, but it does not necessarily
equate to an absolute measure of sustainability. Much depends on what level
the materials are recycled at, and the overall transport distances and energy
use of the work as a whole. The milestones presented in Chapters 5 and 6
provide a qualitative measure of relevant sustainability, but the combination of
measures which is the most sustainable for any application will depend on the
specific circumstances of each site. How can the degree of sustainability be
measured, or various options compared to determine which is the most
susta inable?
Various tools can be used to assess the sustainability of construction projects.
Some concentrate on specific issues, e.g. waste and carbon dioxide emissions,
others provide an overall evaluation of sustainability performance. The following
tools are recommended for use:
site waste management plans;
WRAP’s CO, calculator tool;
WRAP’s Environmental Sustainability of Recycled and Secondary
Aggregates (ESRSA) tool;
The Civil Engineering Environmental Quality and Assessment
(CEEQUA L) scheme.
Site waste management plans
Site waste management plans (SWMPs) are a tool to be used throughout a
construction project to keep a record of the waste arising on sites and the
way they are managed (reused/recycled on site, sent for reuse/recycling off
site, disposed of). They help construction companies and their clients in:
improving their environmental performance, by monitoring arisings against
targets and minimisation of costs and risks;
meeting regulatory controls, by keeping track of arisings and their
management on site or through third parties, to verify compliance with
environmental regulations; and
reducing the rising costs of disposing of waste, through quantification of
arisings and full consideration of the different management options available.
30
Chapter 10 Measuring sustainability
The SWMPs and Code of Practice18were launched by the DTI in July 2004.
In England, SWMPs became compulsory from April 2008 under the Site
Waste Management Plans Regulations 2008. All projects with a value
above f300,OOO require a basic SWMP, with a more detailed SWMP for
projects above f500,OOO. The Welsh Assembly Government is holding a
consultation in 2008 on the introduction of SWMPs in Wales. SWMPs will
not be required by legislation in Scotland. In Northern Ireland, a tailored
version of the SWMPs to suit the local legal situation was published in 2006.19
SWMPs can be used pro-actively to minimise and manage waste, and have
been used by some contractors on major improvement schemes for the
Highways Agency. Many maintenance schemes will fall below the threshold
for compulsory SWMPs, but they will be required for larger schemes. Even
for smaller schemes, SWMPs may prove a useful tool for keeping track
of materials and ensuring they are used to their maximum potential.
The WRAP CO, Emissions Calculator
The CO, estimator tool, available from AggRegain,lo assesses the savings
in CO, emissions that can be realised by using recycled and secondary
aggregates (RSA) andlor in-situ recycling techniques in unbound, bituminousbound, hydraulically-bound and concrete applications. The tool compares
CO, emissions associated with up to three alternative construction options
(e.g. hot or cold asphalt mixing, mix-in-place or mix-in-plant mixtures, different
proportion of RSA, different binders etc.) and identifies the one minimising CO,
emissions. The tool can be used to sum the emissions from construction of
the different layers to give an overall figure for a road. The tool demonstrates
that, in general, road transport and hot techniques are the most energyintensive processes: the choice of local materials and cold techniques can
therefore contribute substantially to the minimisation of CO, emissions.
This is demonstrated by the reconstruction of Rockingham Road, Corby;
the option chosen, which maximised recycling, produced less than a third
of the emissions that conventional reconstruction would have produced.
The WRAP Environmental Sustainability of Recycled
and Secondary Aggregates (ESRSA) tool
The ESRSA tool (Table 10.1), available from the sustainability module on
AggRegain,12can be used to assess and compare the sustainability of
alternative options for the supply of aggregates to a construction site. These
include primary, recycled and secondary aggregates suitable for the chosen
application and sourced within or around the region of the site.
31
Sustainainable Highways: A Short Guide
Rehabilitation of the A6116 Rockingham Road
The stretch of A6116 north of Corby was in structurally poor condition and
required major reconstructive intervention. The client, Northamptonshire
County Council, worked with the supply chain to find a solution that was
fit for purpose while having a high component of material reuse. On-site
ex-situ recycling for the base and binder course materials and a hot-mix
surface course that included 20 per cent recycled materials were
selected in preference to conventional reconstruction of these layers.
The WRAP CO, estimator tool was used to compare the recycled
material option chosen by the team with a traditional primary material
alternative to estimate any difference in carbon dioxide emitted. The tool
was employed to analyse two options as follows:
Option 1 - the traditional maintenance option with primary aggregates
for the bituminous bound materials (hot mix);
Option 2 - as built option with recycled asphalt used for 100 per cent
of the base course aggregates (cold mix) and 20 per cent for the hot
mix surface course.
The outputs generated are:
Conventional maintenance option - hot mix
base course
184 tCO,
+I27 tCO,
As built, recycled option (100 per cent cold
recycled base course + 20 per cent recycled
hot mix surface course)
57 tCO,
-
A large proportion of the difference in CO, emissions, 127 tonnes, results
from the different method of producing the base course. The standard full
reconstruction with all primary aggregates would have used a hot mix
process, and the as built used a cold mix process incorporating the
recycled aggregate.
Source: AggRegain
The tool assesses the sustainability of each material against nine indicators
covering environmental, social and economic sustainability, with the results
represented on a radar diagram: the smaller the area, the more sustainable the
choice of supply. In the example shown in Figure 10.1, use of recycled asphalt
planings was significantly more sustainable than any of the options using
primary aggregates.
32
Chapter 10 Measuring sustainability
Recycled asphalt plannings (RAP)
Limestone/dolomite:
East Midlands
CO2
2
Local
emplc
Water
Price per
tonne
Equivalent
road transport
Resource (natural
raw material use)
Energy
Equivalent
road transport
Resource (natural
raw material use)
Area=20
A rea=33
Land-won: East Midlands
Limestone/dolomite:
West Midlands
CO2
Water
Equivalent
road transport
Local
employment
Resource (natural
raw material use)
Area=33
Equivalent
road transport
Resource (natural
raw material use)
Area=35
Land-won: West Midlands
Equivalent
road transport
Resource (natural
raw material use)
Area=38
Figure 10.1 Example of the output of the ESRSA tool
33
Sustainainable Highways: A Short Guide
rable 10.1 Indicators used in the ESRSA tool
Environmental
CO, emissions
I Natural resources used
Environmentallsocial
Road transport equivalent
*Environmental management system
Social
Social/economic
Economic
Health and safety
I Local employment
I Price per tonne
Civil Engineering Environmental Quality and
Assessment Scheme (CEEQUAL)
The CEEQUAL scheme,*O developed by a team led by the Institution of Civil
Engineers, is based on a comprehensive checklist that assesses all the potential
environmental impacts of a project. CEEQUAL was developed as the civil
engineering equivalent of the BREEAM system widely used for buildings. It is
appropriate for larger projects or a portfolio of small projects, but not for
individual small maintenance projects.
The checklist can be used from design to construction of a project, with the
involvement of the client, the designer and the contractor. Issues such as energy
use, etc. are considered. Chapters 8 and 9 of CEEQUAL deal specifically with
materials and waste. The maximum score available under the Material Use
section is 95 points, while up to 88 points can be scored in the Waste
Management section.
34
CHAPTER I 1
Climate change
In the future, it is likely that climate change will influence the choice of
materials and methods that are used in highway and footway construction
and maintenance. Current research indicates that climate change will take
the form of wetter but warmer winters with less ice and snow, as well as drier
and hotter summers with higher, more extreme temperatures. There may
also be an increase in the severity and number of storms. Consequently,
the local authority highway engineer will need to consider these long-term
factors when selecting materials to be used in a construction or maintenance
project. Guidance on this is given in a separate document,*I also funded
by the Department for Transport and supported by the UK Roads Board.
35
Sustainability is now firmly entrenched in central and local government policy,
and a response is required by local authority highway and material engineers
and their contractors, suppliers and designers. A range of materials and methods
is available to meet this need; they are permitted under existing specifications,
covered by quality protocols, and tools are available to calculate the sustainability
impact of different options. Additional risks posed by their use can be identified
and managed. Guidance is available from a number of sources on all aspects
of their use. Numerous case studies and detailed guidance on how and where
they can be used are available in the companion document to this guidance.*
The amount of recycling in local authority highway works has increased
significantly in recent years, with some local authorities leading the way in the
use of innovative techniques and materials, but this is not universal. There is
still considerable scope for increased sustainability in choice of materials and
methods for local authority highway works in the UK. What is needed to
achieve the full potential is commitment from local authorities to implement
change in a structured and organised way. The aim of this document is to
provide the necessary guidance in a clear and concise way for local authority
highway and material engineers to make this commitment.
In order to provide an impetus, the concept of sustainability milestones for
highway maintenance has been introduced. Three milestones have been
defined, with increasing levels of sustainability. They are intended to be
cumulative, so that a scheme which achieves a rating of Milestone 3 will also
incorporate the relevant measures for Milestones 1 and 2. The measures in
each milestone are based on a qualitative assessment of their sustainability
relative to conventional methods and the extent to which they are readily
available, not on a quantitative evaluation of their whole-life cost or carbon
footprint. The information to carry out such an analysis is not yet available,
though tools to evaluate the relative sustainability of different options in specific
circumstances are described in Chapter 10. The milestones will be reviewed in
a few years’ time.
A sustainability index has also been defined, based on the scores for
milestones for six common applications in highway works and for the extent of
record-keeping shown by key performance indicators. The intention is that this
will provide a spur for local authorities to measure their performance and move
to higher levels.
36
References
Department for Transport (2005). Well-maintained Highways: Code of
Practice for Highway Maintenance Management. TSO, London.
ISBN 0 11552 643 9.
Reid J M, J W E Chandler, I Schiavi, A P Hewitt, R Griffiths and
E Bendall (2008). Sustainable Choice of Materials for Highway Works:
A Guide for Local Authority Highway Engineers. TRL Published Project
Report PPR233. TRL Limited, Wokingham (In Press).
World Commission on Environment and Development (1987). Our
Common Future. The Brundtland Report. Oxford University Press, Oxford.
Department of the Environment, Transport and the Regions (DETR)
(1999). A Better Quality of Life: A Strategy for Sustainable Development in
the UK. DETR, London.
Department of the Environment, Transport and the Regions (DETR)
(2000). Building a Better Quality of Life - a Strategy for More Sustainable
Construction. DETR, London.
H M Government (2005). Securing the Future - Delivering UK Sustainable
Development Strategy. The UK Government Sustainable Development
Strategy. HMSO, London.
WRAP (Waste and Resources Action Programme) (2005a). Recycled
Roads - A Step-By-Step Guide to Local Authority Procurement. WRAP,
Banbury. Available at wwW.aggregain.0rg.uk.
Highways Agency, Transport Scotland, the Welsh Assembly
Government and the Department for Regional Development in
Northern Ireland. The Stationery Office, London. Available at
www.standardsforhighways.co.uk.
Manual of Contract Documents for Highway Works:
Volume I Specification for Highway Works
Volume 2 Notes for Guidance on the Specification for Highway Works.
37
Sustainainable Highways: A Short Guide
Highways Agency, Transport Scotland, the Welsh Assembly
Government and the Department for Regional Development in
Northern Ireland. The Stationery Office, London. Available at www.
standardsforhighways.co.uk
Design Manual for Roads and Bridges
Volume 4 Geotechnics and Drainage
Volume 7 Pavement Design and Maintenance
Volume I0 Environmental Design and Management
Io
l1
Society of Chief Officers for Transport in Scotland (SCOTS) (2006).
A Design and Specification Guide for Scotland's Road Authorities to
Facilitate the Use ofRecycled and Secondary Aggregates. WRAP, Banbury.
Available at www.aggregain.org.uk.
l2
Merrill D, M E Nunn and I Carswell (2004). A Guide to the Use and
Specification of Cold Recycled Materials for the Maintenance of Road
Pavements. TRL Report 611. TRL Limited, Wokingham.
l3
Nunn M E (2004). Development of a More Versatile Approach to
Flexible and Flexible Composite Pavement Design. TRL Report 615.
TRL Limited, Wokingham.
l4
Highway Authorities and Utilities Committee (2002). Specification for
the Reinstatement of Openings In Highways, Second Edition. The
Stationery Office, London.
l5
Roads and Utilities Committee Scotland (2003). Specification for the
Reinstatement of Openings in Roads, Second Edition. The Stationery
Office, London.
l6
WRAP (Waste and Resources Action Programme) (2005b). Quality
Protocol for the Production of Aggregates From lnert Waste. Revised
edition. WRAP, Banbury.
l7
European Union Framework Directive on Waste (2006/12/EC).
l8
www.constructingexceIlence.org.uk//resources. (Last accessed 13/03/2007).
l9
www.cpdni.gov.uk. (Last accessed 13/03/2007).
2o
www.ceequal.com. (Last accessed 13/03/2007).
21
38
wwW.aggregain.0rg.uk. (Last accessed 20/05/2008).
Department for Transport and TRL (2008). Maintaining Pavements in a
Changing Climate. The Stationery Office, London
Useful websites
For information on the use, specification, procurement and supply of recycled
and secondary aggregates and quality protocols: www.aggregain.0rg.uk
For the Manual of Contract Documents for Highway Works and Design Manual
for Roads and Bridges: www.standardsforhighways.co.uk
For information on the Waste Management Regulations: www.netregs.gov.uk
and www.environment-agency.gov.uk/waste.
For location of recycling sites across the UK: www.ciria.org/recycling
For location of recycling and waste management facilities in the vicinity of a
site: www. bremap.co.uk
For UK Roads Liaison Group sponsored codes of practice and other relevant
guidance documents: www.roadscodes.org
Printed in the United Kingdom by TSO
N5841101 C12 06/08
Department for Transport
ISBN 978 0 11 552982 5
fio.50
lnbrmatlon
a publishing rolutlonr
www.tso.co.u k
ISBN 978-0-11-552982-5