About the new Design Manual for Roads and Bridges (DMRB) and what’s new
28 October 2019
What is the DMRB?
Have you ever wondered why UK motorways have a consistent look and feel? Or, how it is that the UK roads and bridges are among the safest in the world? The answer to these questions and many more can be found in the Design Manual for Roads and Bridges (DMRB), a suite of hundreds of documents that define the requirements for every aspect of our road infrastructure. Highways England is currently leading the transformation of the DMRB into a new form, setting the standard for how engineering documents can be drafted, used and maintained in a digital future.
A worldwide impact
The DMRB is focused on the requirements for the UK, but the website data shows that the DMRB has an international reach, with some DMRB documents downloaded millions of times every year. In addition to this, under the open government licence, authorities in non-UK countries are able to use and adapt the content of the DMRB for their own standards and documents. So the current project to update the whole of the DMRB is having an enormous impact, both in the UK and worldwide.
Why is the DMRB being updated?
Refreshing the DMRB by March 2020 is a requirement of Highways England’s Licence and Protocol Agreement. But the other reason for the update is that over a period of about 40 years the DMRB grew by an order of magnitude to a size that became difficult to manage. In 2015, over half the 15,000 pages of the DMRB comprised purely advisory content, not explicitly linked to requirements and with an uncertain status. The style of the documents also varied significantly, depending on when they were written. The average age of the documents in 2015 was 15 years – so the time was right to bring the DMRB up to date and into a consistent, clear format. And updating the whole DMRB provided a unique opportunity to transform the suite into a form that could realise efficiencies of £25 – 50 million and that would be ready to connect to the digital roads environment.
The new documents have been written in a style that clearly states what shall be done, following drafting rules that have been developed from internationally leading research on excellence in standards development. They are much easier to read and understand, and vague or ambiguous phrasing is not permitted.
A new, logical structure
The other big change is in the structure of the DMRB itself. The documents are now arranged according to the technical discipline and the asset lifecycle stage, as represented by the two letters at the start of the new document codes, according to the table below. For example, sustainability and environment documents relating to design all have document codes that begin LD, and civil engineering documents about inspection and assessment all begin with CS. After March 2020 there will no longer be DMRB-related content in “advice” documents or Interim Advice Notes – these are being withdrawn, with the useful and up-to-date content incorporated into the relevant documents and explicitly linked to the requirements. By consolidating the related documents, the total number of documents is reducing by 60%, and all of the relevant content on a topic will be kept in a single, easy to find location.
|G||L||C (Civil engineering)||T (Technology)|
|General principles and scheme governance||Sustainability and environment||Road layout||Pavement||Structures and bridges||Drainage||Geotechnics||Control and communications technology||Road lighting|
|Volume (life-cycle stage)||100-999||100-999||100-199||200-299||300-499||500-599||600-699||100-499||500-999|
|Maintenance and operation||M|
|Inspection and assessment||S|
Where are the new documents?
The new DMRB documents are available, as usual, from the Standards For Highways website. A complete index is maintained in the Design Manual for Roads and Bridges index – GG 000.
Where are the old documents?
Copies of withdrawn and superseded DMRB documents from 2001 onwards can be freely obtained from our new online archive on the DMRB website. Remember to put a space between the code and the number and include a zero for numbers below 100, for example BD 02 or IAN 061. Any document earlier than 2001 can be requested by emailing the Standards Enquiries inbox.
Do the new documents have to be used immediately?
The requirements for implementation of DMRB documents are in GG 101 and referenced from Section 1 of all the new documents.
What has changed in the new documents?
At the start of every document, there is a section entitled Release notes that summarises the changes made in the revision. In addition, there may be further background information in the Introduction section. Highways England also holds a database that details the background to every clause, to assist with responding to technical queries that come through the Standards Enquiries inbox.