Institute of Transport Studies, University of Leeds
Abstract
Construction of the LEeds Freight Transport Model (LEFT) series was begun as part of the
ITeLS project, although other funding has helped and will take forward its development. The
initial version, now referred to by us as LEFT1, was a simple mode split model intended to
give a rough idea of the magnitudes of the effects of various scenarios, possibly as a way of
filtering which scenarios might be investigated using more detailed models. Besides being
limited to mode split, LEFT1 suffered from a range of minor defects and deficiencies which
led to its abandonment in favour of its successor, LEFT2.
LEFT2 was constructed in 2004 as part of the Engineering and Physical Sciences Research
Council LINK FIT project, ITeLS, funded by the Department for Transport (DfT). We
acknowledge here the help and useful comments from many persons associated with that
project. Besides mode split effects, LEFT2 allows scenarios to alter the total size of the (road
plus rail) market. Its purpose is to provide instantaneous ballpark estimates of road and rail
freight tonne kilometres under various ‘scenarios’. At its base is a desire that the scenarios
should not affect the sum of tonnes moved by both road and rail modes. This was because we
felt that our scenarios should be viewed as having a neutral macroeconomic effect. For
example, if taxes on lorry usage were increased, we would expect other taxes to be lower
than otherwise (or government spending to increase) so that total demand in the economy
would not change. Consumers might buy their goods from closer sources than hitherto, but
they would not be expected to consume less in total. For example, if prices of some goods
rose slightly due to higher road user charges, the consumer would have more to spend due to
offsetting reduced income tax (or whatever) and much the same total quantity would be
bought. Similarly, industrialists as a whole might find input prices increasing slightly, but
will find they can charge slightly more for their outputs.
In summary, LEFT2 provides an instantaneous estimate of the effect of macroeconomically
neutral scenarios on mode split (road, trainload and wagonload), average length of haul and
total market size.
LEFT2 does not load the traffic onto vehicles, and so does not produce magnitudes of HGV
vehicle kilometres, for instance. Consequently it does not produce estimates of emissions or
other nuisances. It is hoped that a future version of LEFT can incorporate these elements and
revisit the other matters that have had to be ‘parked’ for the present. LEFT2 gives a quick
idea of the magnitudes of the effects of any policies that might be considered and should help
to provide a first sift where many policies are being considered.
This report describes the basic LEFT Methodology in Section 2. Emphasis is given to that
methodology actually embodied in LEFT2, but there is also some discussion of rejected
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methodologies, and some that have had to be held over for later versions of LEFT. Section 3
presents additional data that was needed by the LEFT2 model. Section 4 describes the
scenarios chosen for testing in the ITeLS project, while section 5 gives the first results from
using the LEFT2 model, for those scenarios
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