the relationship between the VOT and income. MVA Consultancy et al. (1987) and
HCG ( 1990) have found that the value of time increases with income, but less than pro-
portionally. From the results of the stated preference analysis by HCG (1990), we esti-
mate a linear relationship between VOT and income. According to this relationship, the
elasticity of the VOT with respect to income equals 0.368.
The VOT in freight transport is based on De Jong et al. (1993) in which the short and
medium term VOT in freight transport are estimated by means of the contextual stated
preference method. The average VOT over the different goods categories equals 25.8
ECU/h in 1990. The value for 2005 is obtained by assuming that labour cost, which is
one of the main cost components of freight transport, increases by 2% annually between
1990 and 2005.