Question to the Department for Transport:

To ask His Majesty's Government, further to the Written Answer by Lord Hendy of Richmond Hill on 10 November (HL11340), when were the Stated Preference Techniques used in Transport Analysis Guidance assessments last updated.

The Department for Transport’s (DfT’s) Transport Analysis Guidance (TAG) uses evidence based on a range of valuation methods, including Stated Preference (SP) techniques.

The valuations of changes to passenger travel time in TAG are based on a large-scale set of SP surveys carried out in 2014/15, which surveyed 9,000 individuals and businesses to understand travel behaviour, and elicited values relating to travel time and reliability, as well as parameters relating to journey quality. Findings from this research were implemented in TAG in 2017, and are kept under review.

Further guidance on journey quality impacts for bus and active mode travel are underpinned by SP studies undertaken in 2009 and 1996/7 respectively, while evidence on the ‘option value’ of rail travel is drawn from a 2006 SP study.

Aspects of the evidence base in TAG on impacts to life and health, used in the appraisal of environmental and safety impacts, draw on several SP studies undertaken during the 1990s.

The DfT regularly reviews the evidence base underpinning TAG to ensure it remains a robust basis for investment decision-making. This includes commissioning new research using a variety of valuation methods. A notable recent example relates to the 2023 DfT and National Highways-commissioned study into road freight values of travel time, which utilised SP techniques.