The design and interpretation of freight stated preference experiments seeking to elicit behavioural valuations of journey attributes

This paper considers how best to establish user valuations of the benefits for freight traffic from reducing both scheduled journey times and the variability of actual journey times. It first looks at who receives these benefits and establishes a case for delving further. A theoretical discussion then shows that estimated ‘values of time’ are likely to be conflations of several different effects, most probably varying from study to study. Results are then given from a case study where special care was taken to separate out these effects. As an Adaptive Stated Preference method is used, arguments are presented that counter the suggestion that resulting estimates will necessarily be biased. The paper ends with some conclusions.