Transport appraisal: is it time to end reliance on time savings?

The value of travel time savings is central to the appraisal of most transport projects, even though it’s widely accepted that the savings ultimately lead to changes to activity patterns and patterns of development. Former DfT chief scientist David Metz believes it is these latter effects that appraisal should try to measure. But former DfT economist Tom Worsley says the current method is theoretically sound. LTT invited them to an exchange of views, with Tom kicking the discussion off...

22 January 2021

Dear David,

What do we want from an appraisal framework? An appraisal framework must be capable of assessing the full range of economic, social and environmental impacts and presenting them clearly to decision-makers. It should form part of the business case that provides information about the likely outcomes and risks and the resources, both financial and management, required to deliver the intervention.

An appraisal framework requires:

a coherent theoretical framework

facilitation of...