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Data Provider: Welsh Government National Statistics Volume of road traffic by road classification and year
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[Collapse]Road ClassificationBillion vehicle kilometres: Traffic volume is measured using vehicle kilometres, which are calculated by multiplying the annual average daily flow by the corresponding length of road. For example, 1 vehicle travelling 1 kilometre a day for a year would be 365 vehicle kilometres [Filter]
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Road Classification 3
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[Collapse]All majorClick here to sortAll major[Expand]Click here to sortMinor
[Expand]Click here to sortMotorway[Collapse]A CountyClick here to sortA County[Collapse]A TrunkClick here to sortA Trunk
Click here to sortA County - UrbanClick here to sortA County - RuralClick here to sortA Trunk - UrbanClick here to sortA Trunk - Rural


Statistical quality

These statistics are used within Welsh Government for policy formulation and monitoring and are also used to inform other Government departments, businesses, media and the general public. There are no other comprehensive data sources to enable the production of statistics about traffic for Wales and Great Britain. Some specific uses include:
1. Welsh National Transport Plan monitoring indicators include these traffic flow data. The indicator measures the change in traffic flows for Wales as a whole and for individual local authority areas.
2. These data will also be used as part of the calculations to meet any requests for the casualty rate per volume of traffic over individual road links.
3. The national and local CO2 emissions, relating to transport, use traffic flows estimates.

Road traffic estimates are based on the results of many 12-hour daily manual counts in every year, which are grossed up to estimates of annual average daily flows, using expansion factors based on data from automatic traffic counters on similar roads. These averages are needed so that traffic in off-peak times, at weekends and in the summer and winter months (when only special counts are undertaken), can be taken into account when assessing the traffic at each site. DfT now sort roads into 22 groupings (previously there were only 7). This allows a better match of manual count sites with automatic count sites. These groupings were based on detailed analyses of the results from all the individual automatic count sites and take into account regional groupings, road category (i.e. both the urban/rural classification of the road and the road class), and traffic flow levels.


Volume of road traffic, statistical release:


Volume of road traffic in Wales by class of road.

Last update

October 2023 October 2023

Next update

October 2024 (provisional)

Publishing organisation

Welsh Government

Source 1

Manual Traffic Survey, Department for Transport

Contact email


National Statistics

Lowest level of geographical disaggregation


Geographical coverage


Languages covered

English and Welsh

Data licensing

You may use and re-use this data free of charge in any format or medium, under the terms of the Open Government License - see


transport road traffic road classification

General description

The statistics refer to the volume of road traffic in Wales. Road traffic estimates for Wales are compiled by the Department for Transport on behalf of the Welsh Government. These estimates are based on annual roadside manual road traffic counts carried out across Wales during the year. These roadside counts are combined with automatic traffic count (ATC) data and road lengths to produce overall traffic estimates.

Traffic estimates for major roads are based on a census of all such roads whereas traffic estimates for minor roads are estimated by calculating growth rates from a fixed sample of count points on the minor road network. Further details of the methodology are available from the DfT at the link below:
All surfaced roads are included in the estimates. The categories are:
Major roads:
Motorways. Dual carriageways designed for fast traffic with access limited to motor vehicles, and with relatively few places for joining or leaving. The only motorway in Wales is the M4.
A Trunk roads. Part of the strategic road network owned by and operated on behalf of Government
A County roads. All other A roads.

Estimates for A roads are also available with sub-categories for urban and rural roads on StatsWales. Urban roads are those within the boundaries of settlements with a population of 10,000 or more, and rural roads are all other non-motorway major roads.

Minor roads:
B roads. Roads intended to connect different areas, and to feed traffic between A roads and smaller roads on the network.

Classified unnumbered. Smaller roads intended to connect together unclassified roads with A and B roads, and often linking a housing estate or a village to the rest of the network. Similar to ‘minor roads’ on an Ordnance Survey map and sometimes known unofficially as C roads.
Unclassified. Local roads intended for local traffic. The vast majority of roads fall within this category.
Traffic volume is measured using Vehicle Kilometres (VKM), which are calculated by multiplying the annual average daily flow of traffic by the corresponding length of road. For example, 1 vehicle travelling 1 kilometre a day for a year would be 365 VKM over a year. In this release estimates are presented as billion vehicle kilometres (bvk).

Frequency of publication


Rounding applied

Data are rounded to two decimal places. For entries where there are no data, a " * " is used.