Travel Time

A2.56 Values of Travel Time Savings (VTTS) vary according to journey purposes, the characteristics of the journeys being made and the preferences of individual travellers. In the context of transport appraisal, it is standard practice to disaggregate VTTS by 3 journey purpose types:

  commuting - often to/from a usual place of work

  employer's business - journeys made in the course of work

  other non-work - all other trips (such as shopping, leisure and personal trips)

A2.57 The VTTS for employer's business trips represents the opportunity cost to the employer of time spent travelling by their employee. Businesses benefit from reduced travel times include improved access to suppliers or customers, which increase productivity by lowering the cost or raising the quality of inputs and widening the market a business can serve. It is these benefits that form the basis of values of employer's business VTTS.

A2.58 For non-work (commuting and other non-work trips) the VTTS represents the value travellers place on the preferable activities they can undertake in the saved time. For instance, in response to a quicker commute a traveller could choose to spend more time at home with their families or move to a bigger house further away from work.

A2.59 VTTS differs by travelling conditions, for example:

  a higher value is placed on saving walking or waiting time than on saving time spent in a vehicle

  time spent in overcrowded conditions on public transport also carries a higher weight, the value being determined by the severity of the overcrowding

  reliability can also carry a premium and is commonly measured in terms of the standard deviation of journey time or average lateness in the case of public transport

A2.60 Values for use in VTTS are available in the WebTAG data book which is maintained and updated annually by DfT. Further, more detailed guidance on the use of VTTS in transport appraisal and information on the derivation of DFT's recommended VTTS can be found on the DFT webpages.