Reductions in carbon dioxide emissions from an intervention to promote cycling and walking: A case study from New Zealand

Policies promoting active transport, such as walking and cycling, can reduce transport-related carbon emissions. However, there are few studies that examine the carbon emission outcomes of such policies. This paper presents a case study of an intervention carried out in New Zealand that involved the construction of urban cycling and walking infrastructure in parallel with programmes to encourage such active travel. Using vehicle licensing data in the context of a quasi-experimental study design, we evaluated transport carbon dioxide emissions saved. Vehicle distance travelled within the study area was derived from odometer readings that are recorded on the New Zealand licensed vehicle administration system. Using a representative sample of households in the intervention and control areas, we also estimated changes in the number of vehicles licensed per household. Consistent with increases found previously in walking and cycling trips, there was a decline of 1.6% in average distance travelled per passenger vehicle by the third year of the intervention. Averaged across the intervention period, there was a 1% reduction in distance travelled per vehicle and associated carbon dioxide emissions. It is possible that this estimate is conservative as there was indicative evidence from travel survey data that the number of vehicles per household also fell. This is the first study we know of to have shown, using independent and objectively measured data, that the establishment of cycling and walking infrastructure is associated with reduced transport carbon dioxide emissions within a short space of time, even though the reductions found were modest.