Design Manual for Roads and Bridges (DMRB)

The Design Manual for Roads and Bridges (DMRB) is often considered the “Highway Design Bible”. It is a comprehensive series of highway documents, including standards, specifications and standard details. It is specifically designed for use on UK motorways and trunk roads. It has many sections which are not appropriate for local authority roads and is even less suitable around very low traffic roads such as schools and small residential estates.

“On many occasions I have come across young engineers applying asphalt mixes specified to the Design Manual for Roads and Bridges to footpaths going around the side of schools” says Wilsham Consulting Director – Stephen Gibson. “There are enormous differences in design requirement between a motorway and a residential estate. For a motorway the structural strength, from taking HGV after HGV 24hrs a day is critical. For many residential estates, sustainability is far more important.”

Whereas there are some basic elements of physics within the document which are sound, they are often applied completely out of the context for which they were originally written. What we advise graduates is that the correct design for a client, is the design which is appropriate for the specific client requirement and the specific site conditions.

We have experience of both designing major roads to the Design Manual for Roads and Bridges and a multitude of public and private streets. In fact, it is the specialist techniques which have to be used on private roads which are far more involved and complex, than the simple application of DMRB on large projects. Multimillion pound highway projects can be technically simple. The UK has no single highway design guide for normal highway work. Critical, therefore on non Highway Agency (HA) projects, is having an experienced senior Civil Engineer responsible for the road / pavement design.