Health impact model for modal shift from car use to cycling or walking in Flanders: application to two bicycle highways

Abstract

In Flanders, a European hot spot for air pollution, alternatives to car transport are put in place to increase the daily level of physical activity (PA) among the population and reduce air pollution and global warming. To evaluate the economic impact of increased PA (cycling and walking), a health impact model was developed for a given volume of PA, relative to car use, within a defined population in Flanders. Flanders is an interesting region because of the combination of high air pollution, high cycling volumes and good data availability e.g on crashes and PA. The model uses two health indicators: external costs and DALYs. Considered impacts in the model are: mortality and morbidity related to increased PA, air pollution exposure for society and active individuals and crash risks. In addition to health, external costs for CO2 emission, congestion and noise exposure can be considered. The model was applied to the new bicycle highways Antwerp–Mechelen and Leuven–Brussels, which were built near important traffic axes to provide the densely populated region with an alternative to car use. Different sensitivity analyses with a variable number of cyclists and travelled distances were elaborated to check the robustness of the results. Overall, the conclusion was that increased PA outweighed other impacts. The benefit:cost ratio for health impact and infrastructure construction costs was mainly positive, even with conservative assumptions and when the impacts of congestion, noise and reduced CO2 were not accounted for. When reduced congestion was added to the model, benefit:cost ratios largely exceeded one. The model can be used in a retrospective way to analyse previous investments or can be applied to new policy decisions. The presented model is tailored here to the Flemish context for crash risks and air pollution but parameters can easily be adapted to reflect conditions in other regions.