Calculating wider economic impacts: overlap between transport appraisal and agglomeration benefits
Provides perspectives on the current practice used to calculate wider economic impacts (WEIs) of agglomeration in transport appraisal.
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This research provides perspectives on practices used to calculate wider economic impacts (WEIs) of agglomeration in transport appraisal. It focuses on the potential sources of overlap with other elements of appraisal.
The objectives of the report are to:
- explain what is being done in terms of econometric estimation of agglomeration elasticities and in the use of the econometric evidence for practical calculation of WEIs
- comment on the theoretical and methodological case for use of generalised travel costs-based measures of agglomeration in econometric estimation and appraisal calculations
- evaluate the scope for overlap between direct user impacts and WEIs as currently calculated using a distance-based measure of agglomeration
- comment on the potential for overlap between the three categories of WEI that are assessed in UK appraisal
Professor Dan Graham from Imperial College London conducted the research on behalf of the Department for Transport.