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:
https://www.gov.uk/government/publications/road-traffic-speeds-and-congestion-statistics-guidance
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All surfaced roads (excluding Trunk 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 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.

The analysis by vehicle type is based on roadside observation where vehicles are classified according to their general appearance. The vehicle types identified are: 1) Pedal cycles: Includes all non-motorised cycles, 2) Motorcycles: Two-wheeled motor vehicles, including mopeds, motor scooters and motorcycle combinations, 3) Cars and taxis: Includes estate cars, all light vans with windows to the rear of the driver's seat, passenger vehicles with 9 seats or fewer, three-wheeled cars, motorised-invalid carriages, Land Rovers, Range Rovers and Jeeps. Cars towing caravans or trailers are counted as one vehicle, 4) Buses and coaches: Includes all public service vehicles and works buses other than vehicles with less than 10 seats, 5) Light vans: All goods vehicles up to 3,500kg gross vehicle weight. This includes all car-based vans and those of the next larger carrying-capacity, such as transit vans. Also included are ambulances, pick-ups, milk floats and pedestrian-controlled motor vehicles. Most of this group are delivery vans of one type or another, 6) Goods vehicles: All goods vehicles over 3,500kg gross vehicle weight. Includes tractors (without trailers), road-rollers, box vans and similar large vans. A two-axle motor tractor unit without trailer is also included, 7) All motor vehicles: All vehicles except pedal cycles.

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).

Data collection and calculation

Road traffic estimates for Wales are compiled by the Department for Transport on behalf of the Welsh Government. These estimates are based on the 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.

The DfT also produces a geographical website that allows users to view and download estimated traffic flows on every link of the ‘A’ road and motorway network in Great Britain together with the traffic datasets for 2000 to 2019 (major and minor roads):
http://www.dft.gov.uk/traffic-counts/

Frequency of publication

Annual

Rounding applied

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

Weblinks

Volume of road traffic, statistical release: https://gov.wales/road-traffic

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.

Accuracy
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.

Keywords

Transport road traffic local authority excluding trunk roads

Name

TRAN0113