Download Closed Charging Cordon Design Problem

Abstract
The UK Department for Transport (DfT) is currently looking into different methods of designing
closed charging cordons around smaller cities. The DfT’s current scope of interest is to find an
algorithm or method which uses SATURN, a traffic modelling software package, to help find an
optimal or near optimal closed charging cordon for any given network. They are currently using a
genetic algorithm to design and optimize cordons together with SATURN which evaluates each
cordon separately. This method seems to work for small road networks but takes too much
computational time for cities with networks of over a few hundred nodes. This paper suggests
some possible ways in which to approach the closed charging cordon design problem to get faster
computational results while still staying within the DfT’s current scope of interest.
Some parts of the paper discuss ideas that can quickly and easily be implemented to help
decrease the computational time by a small degree. These ideas are “quick fixes” to help get faster
results straight away without investing in extra resources and/or lots of time. One set of ideas are
improvements and suggested changes to the DfT’s current genetic algorithm to help decrease the
number of iterations needed before finding a satisfactory closed charging cordon design. The other
set of ideas comprise of changes to the set up of SATURN to help speed up the evaluation process
of each cordon.
Other parts of the paper discuss future research areas that are strongly suggested to be pursued.
These ideas are more time consuming and need to be researched before they will be able to be
implemented but will likely lead to favourable results. The first is to create a new heuristic algorithm
that uses more local then random searching compared to a GA. The second is to design and
implement a network aggregation algorithm to let SATURN evaluate cordons on a much smaller
but well represented network compared to the original network. Beyond these issues is the
question, for areas like the West Midlands in which there are several cities in close proximity, of
how to model and optimize road charging schemes where a single cordon may or may not be
appropriate.
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