Wells, Andy, Waterson, Ben, McDonald, Mike and Tarrant, David
Accessibility planning for cyclists.
In, 39th Annual Conference of the Universities' Transport Study Group, Harrogate, UK,
03 - 05 Jan 2007.
The UK Government's Accessibility Planning initiative aims to improve access to healthcare, jobs, shops,
services and community facilities by non-car methods of travel, particularly for disadvantaged groups and
areas. Every local authority in the UK is now required to report against a number of indicators in their
Local Transport Plan and Local Development Framework, commonly the distance or time needed to
access a particular location by walking, cycling and public transport. Accessibility for pedestrians and
cyclists is typically measured using a crow-fly distance or the shortest distance on the road network, but
these methods do not account for either cycle and pedestrian routes away from the road network, which
improve accessibility, or physical and psychological barriers to movement, which reduce accessibility.
This paper details a study of cyclists in Southampton, UK, which used Geographical Information Systems
to compare the commonly used crow-fly and road network estimates with actual travel distances for
cyclists, to assess whether improved distance measures could be derived to give better measures of
accessibility. Using a case study of a large shopping centre, the use of crow-fly distance measures was
found to significantly overestimate accessibility, suggesting that local authorities using crow-fly distance
measures should be extremely cautious when presenting and analysing results. Using measures based
on the road network alone was shown to slightly underestimate accessibility, with the error increasing as
the number of cycle routes and other routes available to cyclists increases.
By creating a weighted average of the crow-fly and road network distance measurements, a better
estimate of true shortest cycling distances was achieved. By effectively creating a road network based
accessibility polygon and then expanding it slightly to account for the likely presence of cycle routes
without having to know their exact locations, this paper describes a methodology for local authorities to
improve the accuracy of accessibility assessments until networks including detailed cycle routes and
other routes available to cyclists become available.
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