Previous research investigated the likely effects of permitting longer and/or longer and heavier vehicles in the UK and found that the net effects of the larger options were uncertain, with potential benefits within the road sector but also with the potential for adverse environmental effects. However, the report did suggest that there could be worthwhile benefits from permitting a modest increase in the length of semi-trailers.
In 2008 the Government announced that so-called “super lorries” would not be permitted but that further consideration would be given to allowing longer semi-trailers. A consortium led by WSP and including MDS Transmodal, TRL, and Cambridge University was appointed to undertake further, more detailed research.
Detailed and objective case study data was gathered from the freight industry to add to the subjective views gained previously. The GB freight model was used to provide a more sophisticated estimate of effects than was previously possible. There was some concern that any differences between the two different analyses should be a result of new or more reliable evidence not because of different analytical techniques. This report describes a brief comparison of the techniques used in each study to establish the approximate effects on the results.

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