for Transport calculates average values of time for travel on various modes of transport so that these values can be used to appraise transport projects as part of its New Approach to Appraisal. Some examples are given below in 2002 prices: Car drivers: £26.43 per hour Car passengers: £18.94 per hour Bus passengers: £20.22 per hour Rail passengers: £36.96 per hour* Underground passengers: £35.95 per hour* Walkers: £29.64 per hour Cyclists: £17.00 per hour ∗ Skewed by London wages The US Department for Transport uses the average value of time for infrastructure projects at 50% of the wage rate. Recent experimental research across the US suggests that this value should be 75%. Non-working time This is time spent outside our work, which might include journeys to and from work and leisure journeys. Since this time is not valued in a market, it can only be estimated from revealed preference or stated preference analysis techniques, where the real or hypothetical choices of travelers between faster, more expensive modes and slower, cheaper modes can be examined. For example, if a traveler has a choice between a coach which takes six hours and costs £10, or a train which takes four hours and costs £30, we can deduce that if the traveler chooses the train, their value of time is £10 per hour or more (because they are willing to spend at least £20 to save two hours' travel time). The difficulty in narrowing down the actual value of time from a pair of choices means that hypothetical situations are generally used (the stated preference technique) to deduce values of time. The value of non-working time is linked strongly to utility theory. Forecasting the value of time The value of time cannot be assumed constant over time. Time is a limited good and as productivity and income increase, the relative value of time increases as well. Historically, the projection of the value of time has been closely linked to personal income growth, which in practical applications is typically approximated by GDP growth. Due to a substantial amount of uncertainty in predicting the relationship between income and the value of time, it is common to apply relatively simple “rule-of-thumb” estimates that are measured as elasticity to income. Generally, it is not clear what the elasticity should be, and from a theoretical standpoint there is no reason why the income elasticity for private travel should