British Road Network
The British road network provides a dense coverage of the whole country.
Roads in Great Britain can be divided into two categories:
- Trunk roads: nationally important routes which are maintained by the national highway authority (e.g. in England they are maintained by Highways England). Trunk roads can be found in the following links:
- Non-trunk roads: all other public roads which are maintained by local authorities (city or county council).
The above roads are then classified in:
- Motorways; these are grade-separated expressway and are prefixed with M and have 1, 2 or 3 digit number.
- A-roads; these are major routs (not included in the motorways category) and are prefixed with A and have 1, 2, 3 or 4 digit numbers.
- B-roads; these are local routes and have 3 or 4 digit numbers prefixed with B.
Numbering for these roads is based on nine zones which cover mainland Britain (see Image 1). All the roads that start in a zone take the first digit from the number of the zone. The zones are defined by the roads A1 to A9 and the coastline (with the exception in Kent where the boundary is the river Thames not the A2).
When a new road is built, the highways authority or the local authority assigns a number to it and this number should be included in the new signing and added to existing signage.
Highways standards
It is important to understand the type or road and specifically who the responsible highways authority is, as this will allow understanding what set of standards need to be used for any work undertaken on these roads.
There are three sets of standards:
- Design Manual for Roads and Bridges (DMRB), introduced in 1992 in England and Wales and later in Scotland and Northern Ireland. It includes all current standards, advice notes and other documents relating to the design, assessment and operation of trunk roads, including motorways. DMRB have been reviewed in 2019 to simplify the number of documents and avoid confusion due to inaccuracies between documents.
- Manual for Streets (MfS), first published in 2007 to supersede Design Bulletin 32 and its companion guide Places, Streets and Movement. MfS focuses on lightly trafficked residential streets. Manual for Streets 2 – Wide Application of the principles (MfS2) was published in 2010 and explores in greater detail than MfS how and where its key principles can be applied to busier streets and non-trunk roads.
- Local authority standards. Some local authorities have their own standards to be used in the design, assessment and operation of the network managed by them.
DMRB focuses on high speed roads (above 30-40mph) and on the behavior of drivers and cars although it also considers facilities for other road users (i.e. pedestrian, cyclists and horses). The standards are divided in different sections that cover: sustainability and environment, road layout, pavement, highways structures and bridges, drainage, geotechnics, control and communications technology and road lighting. The design of traffic signs is covered by the Traffic Signs Regulation and General Directions (TSRGD), the latest version of which was released in 2016.
MfS offers more relaxed parameters that help the design process and provide a friendlier design on built up areas, prioritizing pedestrians in the user hierarchy and looking to keep vehicle speed at or below 20mph in streets and places with significant pedestrian movement. MfS covers in detail the design of pedestrian, cyclist and bus facilities, include parameters to design carriageways and junctions including visibility assessment for a town/city environment and finally includes the design of traffic signs and markings as a summary of the TSRGD.
Local authorities’ standards usually offer a relaxation of the DMRB standards based on the requirements of that local area or council. Some of the parameters might be closer to those included in DMRB. Not all the local authorities have their own highways standards or do not cover all the aspects, therefore it is important to check what standards will be required for the adoption of the roads with the local highways officer.
In future articles we will analyse in more detail the information included in DMRB and MfS for a better understanding of both sets of standards.
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