Rethinking travel time valuation in the light of environmental preferences

Reducing travel time emerged as the most substantial benefit justifying transportation projects in cost-benefit analyses, overshadowing environmental costs linked to infrastructures. Although environmental externalities and associated costs are increasingly considered, direct inclusion of additional factors such as environmental preferences in the assessment of benefits, particularly in terms of value of travel time, remains to be explored. There are compelling reasons to consider that individuals may assign differing values to travel time based on ecological integration of a transport infrastructure. We illustrate, using a transportation infrastructure example featuring varying ecological integration, that the subjective value of travel time can be significantly influenced by individuals’ environmental preferences. We evaluate preferences through a national-scale choice experiment with trade-off between infrastructure ecological integration and travel time. A significant proportion of individuals is willing to forego travel time reductions for an infrastructure offering greater ecological integration. However, among individuals less connected to nature, the most disadvantaged appear to lack choice of sacrificing travel time to better accommodate ecological considerations, while a more affluent minority prefer not to take biodiversity into account when considering the impact on travel time. Environmental preferences are thus key factors to consider in transport project assessment, as ecological feature may impact the value attributed to travel time.