Memorandum by dhc Transport Research and
Consultancy (TYP 7)
10 YEAR PLAN
INQUIRY
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.
Congestion
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.
Conflicts
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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