Question to the Department for Transport:

To ask His Majesty's Government, further to the Written Answer by Lord Hendy of Richmond Hill on 27 November (HL11894), why time changes of such small increments are used in the calculation of journey saving; and what assessment they have made of the extent to which time changes in these increments can be depended upon.

Our approach to the modelling and appraisal of journey time changes is intended to capture the behavioural choices of travellers, and the resulting impacts on the welfare of society.

There is evidence from everyday life of individuals making choices that suggest they value very small time savings. For instance, pedestrians may choose to cross rather than wait for traffic lights to change, while travellers may rush to catch an underground service, to save 1-2 minutes.

The most recent national study into passenger values of time (Arup et al, 2015), considered this issue, and we provided the rationale for capturing the full range of sizes of time saving as part of our 2016 consultation response on values of travel time.

Firstly, that appraisals are carried out ‘at the margin’ for an incremental scheme, and hence capturing time savings of any size and valuing them at a constant unit value provides a robust mathematical framework to aggregate impacts in a consistent fashion across appraisals.

Furthermore, to ensure a representative approach, we want to reflect the full spectrum of sizes of time saving attributable to different kinds of schemes and different modes. Our approach to the capturing of small time savings is consistent with appraisal frameworks in other countries, for example Sweden.

We intend to gather further evidence on the value of small increments of time savings as part of the next national value of time study, currently being planned.