i sustainable highways: 1 ashortguide

I Sustainable Highways: 1 AShortGuide

Department for

Transport

,Iqr . rAr June 2008 U K R O A D S B O A R D

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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Contents

I.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

Introduction

Sustainable construction

Linking to corporate objectives

How to build a sustainable road

Materials, methods and milestones

Key performance indicators and sustainability index

Specifications and quality control

Environmental impacts

Waste management regulations

Measuring sustainability

Climate change

Conclusions

References

Useful websites

5

6

8

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13

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35

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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 2005,6 and 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 They consume large quantities of construction materials and generate large quantities of waste.

FI The extraction, processing and transporting of these materials is a significant source of greenhouse gas emissions, particularly in the production of cement and asphalt.

EI 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:

Reduce the levels of waste produced. Reuse products wherever possible. Recycle what cannot be reused.

BI Recover energy from waste that cannot be reused or recycled. Dispose of materials only as a last resort.

6

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

Chapter 4 How to build a sustainable road

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 incorporate sustainability 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

Sustainainable Highways: A Short Guide I

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. I

10

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 step- by-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


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

1

2

3

Use primary aggregates and hot asphalt or concrete for all applications.

Dispose of arisings to landfill or an exempt site.

Cold in-situ or ex-situ recycling of existing bituminous or concrete pave men t . Use up to 30 per cent reclaimed asphalt in new hot asphalt.

Recycle arisings as unbound subbase or capping.

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.

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

3

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.

~~ _ _ _ _ _ _

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.

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Footways and cycle tracks Description of works:

repairs to existing footways and cycle tracks; construction of new footways and cycle tracks.

0

1

2

3

Use primary materials and hot asphalt for all applications.

Dispose of arisinas to landfill, exempt sites or farmers’ tracks.

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.

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.

Use lime and/or hydraulic binders to treat existing soils and avoid need for imported subbase and base.

17


Capping and subbase Description of works:

repairs to existing capping and subbase; capping and sub-base in new construction.

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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 pave men t . 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).

2

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.


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

1

2

3

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 . 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.

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.

Use lightweight aggregate, such as pulverised fuel ash, expanded polystyrene, expanded clay or tyre bales, for earthworks over deep weak subgrade to limit settlement.

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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 Exce I I en ce , Q PA) .

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.

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

1

2

3

No recycling carried out, or recycling not recorded.

Percentage of waste sent for recycling.

Percentage of waste sent to landfill.

Percentage of recycled materials used (by volume or value), overall or in specific applications.

Cost savings due to recycling.

~ ~~

Percentage of waste recycled on site.

Percentage of imported recycled materials (by volume or value).

Percentage of work for which recycling is specified (i.e. required, not optional).


Reduction in construction waste.


Percentage of all aggregates sourced within a specified miles/ km radius.

Savings in emissions of CO,.

No formal system for recording amount of recycling or diversion of waste from landfill.

E.g. up to 100 per cent of all bituminous bound arisings.

In line with overall targets for the local authority.

Baseline values or minimum/low risk accepted within standard specifications.

Positive (i.e. cost savings rather than losses).

account industry good practice.

on site.

Commerce advises setting 10 per cent (by value) as a minimum, but work undertaken by WRAP has demonstrated that higher values can be achieved.

Incrementally increased from baseline and/or industry good practice.

Project-specific, taking into

Relate to available material

The Office of Government

Project-specific, taking into account industry best practice.

Incrementally increased from Level 2 and/or industry best practice.

The maximum, considering technical requirements (e.g. high PSV aggregates might need to be imported).

Positive, i.e. savings with respect to existing practices.

21

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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).8 They 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),g which 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:

Volume 4 Geotechnics and Drainage; Volume 7 Pavement Design and Maintenance;

H Volume 10 Environmental Design and Management.

Of particular importance is HD 35/04 (Vol. 7 Part 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

which deals with conservation

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 61112 and 61513 and 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.14 In Scotland and Northern Ireland, the equivalent document is the Specification for the Reinstatement of Openings in Roads.15 The 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


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 J J J J J J J

x J J J J I( I(

J J J J J J

Burnt colliery spoil China clay sand1 stent Coal fly ash/ pulverised fuel J J J J J J J ash (CFA/PFA) Foundry sand J J J J J . J J

J J J x J x x Furnace bottom ash (FBA) Incinerator bottom ash J J J J J J J aggregate (IBAA) Phosphoric slag J J J J J J J

J J J J J J J Recycled aggregate (RA)

J J J J J J Recycled asphalt (RAP)

J J J J J J J Recycled concrete (RCA) Recycled glass J J J J J J I(

Slate aggregate J J J J J J J Spent oil shale I( J J J J x x Steel slag J J J J J J I(

x J I( I( J I( 8 Unburnt colliery spoil

24

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).

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 alkali- silica 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.

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.

2

3

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 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.

U 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 Scient if i c I n te rest (SSS I s).

quality protocols before use, and avoid use in unbound applications below the water table.

protocol, if one is available. Many suppliers provide guidance on the use of their materials, and this should be followed.

EI Liaise with the local Environment Agency officer if you have any concerns.

rn Ensure all slags and ashes are properly weathered in accordance with

EI Ensure materials are produced and used in accordance with a waste

26

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


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 - h aza rdo u s; 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 (f 32/tonne from April 2008, rising at f8/year, compared to f 2.50/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 sustaina bility

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 sus ta i na bl e?

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 (C E EQ U A 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 Practice18 were 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, bituminous- bound, 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 energy- intensive 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,12 can 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


Conventional maintenance option - hot mix base course

recycled base course + 20 per cent recycled hot mix surface course)

184 tCO,

As built, recycled option (100 per cent cold 57 tCO,

Rehabilitation of the A6116 Rockingham Road

+I27 tCO,

-

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:

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)

2

Equivalent Resource (natural road transport raw material use)

Area=20

Local emplc

Limestone/dolomite: East Midlands

CO2

Water

Price per Energy tonne


A re a = 3 3

Land-won: East Midlands Limestone/dolomite: West Midlands

CO2

Local Water employment



Area=33 Area=35

Land-won: West Midlands


Area=38

Figure 10.1 Example of the output of the ESRSA tool

33


Environmental

rable 10.1 Indicators used in the ESRSA tool

CO, emissions

Environmentallsocial

Social

I Natural resources used

Road transport equivalent

*Environmental management system

Health and safety

Social/economic I Local employment

Economic 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.standardsforhig hways.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


38

Highways Agency, Transport Scotland, the Welsh Assembly Government and the Department for Regional Development in Northern Ireland. The Stationery Office, London. Available at www. standardsforhig hways.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

I o wwW.aggregain.0rg.uk. (Last accessed 20/05/2008).

l 1 Society of Chief Officers for Transport in Scotland (SCOTS) (2006). A Design and Specification Guide for Scotland's Road Authorities to Facilitate the Use of Recycled and Secondary Aggregates. WRAP, Banbury. Available at www.aggregain .org .u k.

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.

l 3 Nunn M E (2004). Development of a More Versatile Approach to Flexible and Flexible Composite Pavement Design. TRL Report 61 5. TRL Limited, Wokingham.

l4 Highway Authorities and Utilities Committee (2002). Specification for the Reinstatement of Openings In Highways, Second Edition. The Stationery Office, London.

l 5 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.u k. (Last accessed 13/03/2007).

2o www.ceequal.com. (Last accessed 13/03/2007).

21 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