Highways Agency

Frequently Asked Questions

What are the Eurocodes?

The Eurocodes are pan-European structural design codes.  There are ten Eurocodes in a total of 58 parts covering: basis of design; actions on structures; design of structural elements in concrete, steel, composite steel and concrete, timber, masonry and aluminium; together with geotechnical and seismic design. They cover the design of bridges, buildings, silos, tanks, pipelines, towers, masts and more.

Why develop Eurocodes?

In 1975, the Commission of the European Community decided on an action programme in the field of construction based on Article 95 of the Treaty of Rome. The objective of the programme was the elimination of technical obstacles to trade and the harmonisation of technical specifications. The introduction of Eurocodes will eliminate the technical obstacles to trade that exist because of differing design codes in Europe, and will harmonise technical specifications for public procurement, thus creating a more open marketplace.

The introduction of the Eurocodes will, in theory, enable access to a marketplace estimated in 2004 at £1.5bn annually, and will allow greater opportunities for harmonised research across the Union, saving a considerable amount of money.

What are the National Annexes?

The Eurocodes allow choice of safety related parameters and certain country-specific data, known collectively as Nationally Determined Parameters (NDPs).  Each country can publish its chosen values for the NDPs in a National Annex that will accompany the Eurocode part.

The parameters left open for national choice are, generally: partial safety factors; the chosen design life for structures; country specific data such as snow maps, wind maps, isotherm maps and seismic maps; certain additional information on aspects such as durability; some additional safety-related parameters; and decisions on the status of informative annexes in the Eurocode part.  In addition, the National Annex may contain references to non-contradictory complementary information.

The National Annex combined with the national title page and national foreword form the British Standard implementing the European Standard.  In effect, this means that the Eurocode cannot be used for design until the National Annex is published.

What are the differences between the Eurocodes and the British Standards? Is there a different design philosophy?

The Eurocodes are limit state codes like the British Standards, although are perhaps a little more explicitly based in reliability theory.  Many of the Eurocode rules are based on the same theory as the British Standards, although the Eurocodes embody the most up to date research on many aspects of structural behaviour.

The Eurocode clauses are structured in a slightly different way in that they contain principles that must be satisfied and application rules that offer a way of satisfying the principles.  This is intended to stimulate innovation.  The Eurocodes are also less prescriptive than the British Standards, with more aspects left open to the designer.

Are the Eurocodes mandatory?

Under the Public Procurement Directive, the Member States must accept designs to the Eurocodes. When published, the Eurocodes will become the standard technical specification for all public works contracts: where a contract for a public body contains a technical specification this should reference the appropriate European Standards. It will not be mandatory to design to the Eurocodes in the UK, but if a designer proposes alternative design standards then they will have to demonstrate the alternative is of 'technical equivalence' to a Eurocode solution. As the British Standards Institution (BSI) will not maintain the withdrawn UK standards, in reality there will be little option but to use the Eurocodes.

The engineering industry is therefore encouraged to prepare for the changeover to Eurocodes as soon as practicable.

What is the target date for the introduction of Eurocodes to the UK?

All 58 Eurocode parts are now available, and most of the National Annexes are expected to be published by the end of 2008.  The Eurocodes will co-exist with the current National Standards until March 2010 at the latest, when BSI is expected to withdraw all conflicting National Standards and the Eurocodes become the main structural design standards.

When will the Eurocodes be used for bridge design?

The final National Annexes required for UK bridge design are expected to be published in December 2008.
For Highways Agency’s schemes, the requirements to use Eurocodes for the design of bridges and other highway structures will be introduced via a new implementation standard in the DMRB, which will cover changes to the existing DMRB standards in relation to the introduction of Eurocodes.  The Agency expects to publish the implementation standard soon after the final bridge National Annexes are published.

Find out more about the Agency’s strategy for the Implementation of Eurocodes.

How will the Eurocodes relate to the DMRB?

The review of the existing DMRB with regard to Eurocodes is ongoing and the Agency is taking the opportunity to rationalise the content with a view to making it consistent with the principles of Eurocodes. There will be fewer, more focussed DMRB parts that contain the additional (non-contradictory) requirements of the Overseeing Organisations.  An initial preliminary review shows that some of the DMRB standards may have to be withdrawn like the National Standards, some should be modified to align with the design rules in the Eurocodes, while others could remain unchanged to support the assessment standards.

In addition to the DMRB, we are working with BSI’s bridges committee to prepare non-contradictory complimentary information (NCCI) for the design of highway structures as Published Documents.  We are also discussing the publication of additional guidance information with various industry bodies.

What are BSI Published Documents? 

Published Documents, or PDs, are BSI documents that hold a lower status than a Standard.  Some UK specific non-contradictory complementary information (NCCI) for bridges will be published in PDs and this information will be referenced in the National Annexes.  Much of the NCCI is likely to be from the current National codes that will be withdrawn, but a wide variety of NCCI from other sources will also be referenced.

The BSI intends to publish a number of PDs relating specifically to the design of bridges.  This includes background information for the National Annexes, and in some cases residual information from BS 5400 that has been adapted to compliment the Eurocodes, for the following parts of the Eurocodes:

• Actions: BS EN 1991-1-4 (wind actions), BS EN 1991-1-5 (thermal actions), BS EN 1991-1-7 (accident actions) and BS EN 1991-2 (traffic actions
• Materials: BS EN 1992-1-1 (concrete general), BS EN 1992-2 (concrete bridges), BS EN 1993-1-9 (fatigue in steel), BS EN 1993-1-10 (fracture in steel), BS EN 1993-2 (steel bridges) and BS EN 1994-2 (composite bridges)
• Geotechnics: BS EN 1997-1 (geotechnics general, including additional complimentary information on the design of geotechnical aspects for bridge elements such as foundations, earth retaining structures and integral abutments)

Some of the PDs mentioned above have already been published.  For a full publication schedule refer to the BSI website.

How will the Eurocodes affect Technical Approval Procedures?

The role of the TAA is considered essential in ensuring safety and reliability even after Eurocodes are implemented, by ensuring compliance with standards.

The current Technical Approval Procedures are in the process of being reviewed to identify amendments required to accommodate the use of Eurocodes.  It is expected that the existing model AIP form will need to be modified to accommodate the use of Eurocodes.  Changes that may be required include Loading Criteria, the Technical Approval Schedule and possibly a new appendix in which designers record options and choices where allowed by the Eurocodes.

Are the Eurocodes as safe as current UK standards?

The Eurocodes are regarded to be safe and reliable and have already been used in Europe on a number of landmark structures.

The Agency is reviewing the Eurocodes with regard to safety and economy. The partial safety factors in the National Annexes are determined by the UK and will ensure a level of reliability compatible with the existing UK standards.

Will Eurocode designs cost more to construct?

The numerous studies carried out so far indicate that the Eurocodes will have little or no effect on member sizes and quantities for common design situations.  The Highways Agency is continuing to review the Eurocodes with regard to economy.  It is likely that the less prescriptive approach of the Eurocodes will allow greater scope for innovation and encourage designers to use advanced analysis techniques, potentially leading to better value for money.

Are Eurocodes for assessment or just for new design?

The Eurocodes are only for new design. However in certain situations they could also be used as a basis for assessment as a departure from standard with the agreement of the appropriate Overseeing Organisation.

Will there be design guides for the Eurocodes?

Yes. Thomas Telford is producing a set of design guides, many of which are now published, and industry bodies are developing a considerable amount of additional guidance.

Will we have to re-assess all of our bridges to the new Eurocode loading and principles?

No, the assessment programme will not be affected by the changeover to Eurocodes.

What is BSI's involvement in the Eurocodes?

BSI holds the secretariat for CEN technical committee TC250, responsible for the Eurocodes, and is the lead organisation for Eurocodes in Europe.  BSI publishes the Eurocodes as BS EN standards and is the secretariat for the British Committees that oversee British interests in the Eurocodes.

How is the Highways Agency involved? 

The Highways Agency is reviewing and commenting on the Eurocodes insofar as they relate to bridges, influencing the National Annexes relating to the General parts of the Eurocodes, and writing the National Annexes relating to the bridges and other highway structures parts of the Eurocodes.  We have provided the National Technical Contacts for the Bridge parts of the Eurocodes and played an active part in the development of the Eurocodes in the early years.  We have also played an instrumental role in the preparation of the BSI Published Documents containing NCCI for UK bridge design.

Find out more about the Agency’s role in Eurocodes.

With which Authorities is the Agency co-ordinating?

With BSI; Communities and Local Government; BRE, Communities and Local Government's consultant on the Buildings and General Eurocodes; the Department for Business, Enterprise and Regulatory Reform (formerly DTI); the Office of Government Commerce (OGC); CSS; Network Rail, and Overseeing Organisations in Scotland, Wales and Northern Ireland.

How is highway loading addressed in the Eurocodes? 

Normal highway loading is specified in Eurocode 1 Part 2 and supplemented by provisions in the National Annex.  This load model comprises a tandem axle system acting in conjunction with a uniformly distributed load.  Abnormal loading is specified in the National Annex to Eurocode 1 Part 2.  The implementation standard will specify which special vehicle load model is appropriate depending on the type of highway.

Will example bridge designs be carried out? 

The Agency has carried out several studies using the Eurocodes to design typical highway bridges to examine their effect on safety, economy, technical approvals, specification and to establish the need for additional guidance.

It is expected that industry bodies will publish example bridge designs using Eurocodes.

What is the impact of Eurocodes on HA procurement?

As the use of Eurocodes will be through the DMRB, the impact of their use on the procurement and contract documents should broadly be as for other changes in standards.  The only difference will be that during the period of coexistence of the two sets of design codes, design to either will be acceptable.  The issue of how long a design to the current National codes in a long-running design programme will remain acceptable to us beyond the date of withdrawal of those codes is being considered.

How will Eurocodes affect the Specification for Highway Works (SHW)?

The Agency is reviewing the SHW to determine how it will be affected by the Eurocodes and what changes will be required.  The SHW will have to reflect the European product standards and in many cases already does so.  Additionally, the European Execution Standards contain workmanship and erection specifications that will replace the equivalent requirements when published.  These changes will also be incorporated in the amendments to the SHW.

What is the progress of the European Execution Standards?

EN1090 – Execution of steel and aluminium structures

Both EN 1090-2 (for steel) and EN 1090-3 (for aluminium) have received the formal vote.  They are expected to be published as a BS in late 2008.

The Highways Agency is in the process of updating the SHW to align with EN 1090.  A new model specification incorporating the changes has been drafted and is being reviewed.  It is expected to be published in early 2009.

EN13670 - Execution of concrete structures

It is anticipated that EN 13670 will be finalised and published near the end of 2008.  The Highways Agency has already developed a draft update to the SHW and related Notes for Guidance to take account of EN 13670.  Publication will be held in abeyance until EN 13670 is finalised.

What is the relationship between the Eurocodes and the European Product Standards?

Product Standards exist for construction products, establishing requirements for performance and other properties so products meet the Essential Requirements of the Construction Products Directive. Eurocodes are codes that are concerned with the design of structures.  Eurocodes are generally written on the assumption that structures designed in accordance with the Eurocodes will be constructed from products manufactured in accordance with the product standards.  Eurocodes can cross-refer to product standards and may form the basis of design for products.

Are tunnels covered by the Eurocodes?

Yes, however the information is often limited and further information should be given in guidance documents.

Who is implementing the Eurocodes for buildings?

Communities and Local Government.

How do the general/buildings parts of the Eurocodes relate to bridges?

For most Eurocodes the general part (Part 1-1) is used for building design.  For bridge design, Part 2 is used in conjunction with Part 1-1 where appropriate.

How will Eurocodes be maintained?

Procedures for the care and maintenance of Eurocodes have been developed and this will be supported by the CEN (European Committee for Standardization) committee structure and the national Standards Bodies.  The correction of errors will be handled by issuing corrigenda and it is expected that the Eurocodes will be updated on a five-year cycle.

Will lack of software inhibit the implementation of Eurocodes?

Some software providers have already reached an advanced stage in the development of Eurocodes-aligned software.

How is progress on Eurocodes being communicated?

By periodic briefings in industry publications and by seminars such as those held in 2007 at the Institution of Civil Engineers and Institution of Structural Engineers, and those organised by the industry bodies across the country.  Additionally and more importantly, comprehensive information about all aspects of the Eurocodes can be found on the Eurocode Expert website.  Progress on the Highways Agency implementation strategy for the Eurocodes is given on this website.

What is the impact on research output?

Research for design codes is likely to be pan-European, so the output from the research will benefit all member states, thus making code-based research more efficient and more widely-beneficial.

Where can I purchase the Eurocodes?

BSI is publishing the Eurocodes in the UK and these can be purchased through them or via various other standards subscription services.  All of the Eurocodes are now available for purchase; the National Annexes are in the process of being published.