Road Traffic and Congestion in Great Britain: Quarter 1 2008

This bulletin includes statistics on Traffic in Great Britain for the first quarter of 2008. Figures for 2007 and 2008 are provisional. Final 2007 figures will be published in July 2009 and are liable to differ slightly from the provisional figures. The provisional figures indicate that there was no overall change in estimated levels between the first quarters of 2007 and 2008. The bulletin includes analyses by vehicle type and road class. Key results include: Between the first quarters of 2007 and 2008;

• Car traffic decreased by 2 per cent
• Light van traffic increased by 6 per cent
• Heavy goods vehicle traffic increased by 3 per cent
• Traffic on motorways increased by 2 per cent  
• Traffic on both rural 'A' roads and minor rural roads increased by 1 per cent
• Traffic on both urban 'A' roads and minor urban roads fell by 2 per cent

Inter urban congestion

This quarterly bulletin also includes National Statistics on congestion on motorways and trunk roads in England used to monitor the PSA measure on inter-urban congestion. Between the baseline year (August 2004-July 2005) and the target year (April 2007-March 2008):

• Average Average vehicle delay on the slowest 10 per cent of journeys rose from 3.78 to 3.95 minutes per 10 miles

Congestion in major urban areas in England

This bulletin contains statistics for monitoring the PSA target on urban congestion.

2006-07 person journey times across the ten largest urban areas were 2.4 per cent faster than in the baseline. In the baseline year person journey times were 3.85 person minutes per mile, falling to 3.75 person minutes per mile in 2006-07. Over the same period, person miles travelled fell by 1.5 per cent.

1. The quarterly estimates are based mainly on data from 190 Automatic Traffic Counter (ATC). Caution should be taken in drawing conclusions about longer term trends from a single quarter's or year's estimates.

2. The final annual road traffic estimates are calculated from data collected by both the ATCs and 10,000 12-hour manual counts, combined with road lengths. Final annual traffic estimates for 2007 will be presented in the Statistical Bulletin Road Statistics 2007: Traffic, Speeds and Congestion, due to be published in July 2008.

3. The next quarterly bulletin will be published on 7 August 2008.

4. The figures on traffic levels are measured in terms of vehicle kilometres and are sometimes known as the volume of traffic. This is not the same as congestion. For example, traffic levels could increase without increasing congestion if traffic is more evenly spread during the day, with less during peak periods and more at other times. Congestion has a number of consequences, such as causing delays and making journey times unreliable.

5. The indicator used to monitor inter-urban congestion is the average delay in minutes per 10 miles (derived from the differences between observed journey times and a reference journey time) experienced on the worst 10 per cent of journeys for each monitored route. The Department has a Public Service Agreement (PSA) target to make journeys more reliable on the Strategic Road Network (SRN) in England. The target will be achieved if the average vehicle delay on the SRN's slowest 10 per cent of journeys is less in target year 2007-08 than in the baseline period. Currently, because of data quality issues, 91 of the 103 routes are used to monitor network performance. More information can be found at: http://www.dft.gov.uk/pgr/statistics/datatablespublications/
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6. The inter-urban congestion data are now National Statistics. The data for March 2008 are provisional because there has not been full quality assurance at a route level, but it is unlikely that they will be revised. Provisional data for April and May 2008 will be published on 5 June and 3 July 2008 respectively.

7. Congestion in urban areas is measured by "person journey time per mile". The Department's urban congestion PSA target states that by 2010-11, the ten largest urban areas will meet the congestion targets set in their local transport plan relating to movement on selected main roads into city centres. The target will be met if person journey times in the ten largest urban areas increase from the baseline by no more than 3.6 per cent by 2010-11, in the context of travel volumes increasing by 4.4 per cent.

8. The urban congestion data are experimental statistics that are under development and are being tested for their ability to meet user needs. More detailed information about the methodology used for the calculations is published in the Technical Note - PSA 4, published on the DfT website at: http://www.dft.gov.uk/about/howthedftworks/psa/spendingreview2004psatargets2

9. The urban congestion baseline uses data from both 2004-05 and 2005-06.

10. The volume of travel is the number of people using the roads, rather than the number of vehicles.

Publication details

Published on 8 May 2008 by Transport Statistics.

The next bulletin in this series will be published on Thursday 7 August 2008

Email: roadtraff.stats@dft.gsi.gov.uk for queries concerning this bulletin.

For information about release of this product see National Statistics Online.