Why railway passengers are more polluting in the peak than in the off-peak; environmental effects of capacity management by railway companies under conditions of fluctuating demand

Given the difference between peak and off-peak occupancy rates in public transport, the average emission per traveller kilometre is lower in the peak than during the off-peak period. However, in this paper it is argued that it is much more fruitful to analyse environmental effects in marginal than in average terms. The issue appears to depend on capacity management policies of public transport suppliers that are facing increases in demand both during the peak and off-peak period. A detailed analysis of capacity management of the Netherlands Railways reveals that the off-peak capacity supply is mainly dictated by the demand levels during the peak period. Topics that receive attention in the analysis are the effects of frequency increases and size of vehicle increases on environmental effects. Also environmental economies of vehicle size are taken into account in the analysis. The main conclusion is that the marginal environmental burden during the peak is much higher than is usually thought, whereas it is almost zero at the off-peak period. Thus, one arrives at a pattern that is entirely reversed compared with the average environmental burden: peak passengers are more polluting than off-peak passengers. The conclusion is that policies based on average environmental performances would lead to misleading conclusions.