Standards for the preparation, design and construction of motorways and trunk roads.

First published:
19 January 1996
Last updated:

We manage the Highway Standards and associated guidance to be used in Wales.

We identify the administrative and technical requirements for the planning, preparation, design and construction of highway works. We do this through the publication of standards and specifications to be used on the motorway and trunk road network in Wales.

The Highway Standards which apply to the Welsh motorway and trunk road network are contained in the Design Manual for Roads and Bridges (DMRB) and the Manual of Contract Documents for Highways Works (MCHW).

Both the DMRB and the MCHW are national standards applicable throughout the UK, produced by the Highways England in conjunction with the governments of Wales, Scotland and Northern Ireland.  

We publish associated guidance documents which support the UK Highway Standards defined in both the DMRB and the MCHW.  These associated guidance documents are divided into:

  • interim advice notes (IANs) – provide supplementary guidance not contained within current standards
  • procedure and advice guidance (PAG)
  • street works guidance

Interim advice notes

Interim Advice Notes (IANs) provide supplementary guidance not contained within current standards.

IANs are first issued by Highways England and are listed on the Highways England website. These are only used in connection with works on motorways and trunk roads in England.

Interim Advice Notes Wales: IAN (W)

Once IANs have been issued by Highways England they are then considered for adoption on the Welsh motorway and trunk road network by us. Then the IANs which are considered appropriate for adoption on the Welsh trunk road network are issued by us as an IAN (W). They follow the Highways England numbering system with the year of issue in Wales and the suffix (W), e.g. IAN 154/14(W)

Any IAN issued by the Highways England, but not issued as an IAN (W) is not for use on the Welsh motorway and trunk road network.  This may be because the IAN is not considered suitable for the Welsh network, or that the merits of the IAN are still being considered by us. For clarification on the status of any IAN in Wales please email us at; Standards_Feedback_and_Enquiries@gov.wales

Sometimes we develop our own IANs and these have a unique number system following a 1000 series and include the year of issue in Wales along with the suffix (W), e.g. IAN 1001/15(W).

You can find all the published IAN (W) s below.

Reading IANs

Some IANs must be read in conjunction with the Design Manual for Roads and Bridges (DMRB) and the Manual of Contract Documents for Highway Works (MCHW), whilst other IANs provide stand alone guidance and may be related to other documents, such as Chapter 8 of the Traffic Signs Manual, or relate to specific situations such as environmental cases (e.g. Ash dieback disease).

Procedure and advice guidance

Technical requirements for the planning, preparation, design and construction of highway works which is not contained in either Highway Standards (DMRB/MCHW) or the IANs (W).

Guidance on our procedures which relate to the planning, preparation, design and construction of highway works on the Welsh motorway and trunk road network.

Street works guidance