Select Committee on Transport, Local Government and the Regions Appendices to the Minutes of Evidence

Memorandum by dhc Transport Research and Consultancy (TYP 7)


  In response to the Committee's invitation to submit memoranda on aspects of the 10 year plan I have a few comments to make on the targets.


  If congestion targets are to be used, then the definition of congestion needs to be clarified (CPRE 2000), and practical and affordable ways of measuring congestion set in place. Congestion is mainly of significance to transport users because it lowers their levels of accessibility by increasing travel time and cost.

  There are therefore strong arguments that accessibility targets would be preferable to congestion targets. This would allow improvements by each mode to be measured consistently demonstrating balance within the plan, and would permit integrated targets to be set for multi-modal trips by trip purpose (see DHC 2000 for more details).

  Simple accessibility indices such as travel time could allow the development of a national travel time index where travel times between a network of origins and destinations in Britain are monitored. Other accessibility indices could look at population catchments for travel to work in major cities or by trip purpose, more explicitly linking land use and transport (see DHC 2001a).

  Travel time indices also lend themselves to measuring the reliability of travel which is particularly important for freight. A recent paper for CfIT suggested that the most effective congestion index was in fact travel time index (ie an accessibility index) since this allowed variations in travel time to be shown as a reliability measure (McKinnon 2001).

  Accessibility measures have the major advantage of describing the transport system as users see it rather than congestion which measure the transport system from the viewpoint of operators. If targets mean something to the general public then people and businesses are more likely to support the policies to deliver them.


  For rural transport, the plan states that its objective is to improve accessibility to jobs, shops, health etc. However it sets a target to "Achieve a one third increase in the proportion of households in rural areas within 10 minutes walk of an hourly or better bus service". In some parts of the country the target could work against the objective by encouraging authorities to divert funding to achieve hourly bus services rather than tackle problems of rural accessibility (DHC 2001b).

  It would be better for integrated accessibility targets to be set which link transport with wider issues such as social inclusion, rural development or other aims (eg to improve by a third access for people on income support to jobs). These integrated measures would be easier to calculate (from readily available data on people, locations of jobs and public transport travel times), that the access to hourly bus services measure, and would provide a direct indication of whether the overall objectives are being met.

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