ViaStrada delivered a working paper summarising the methodology and calculations to derive estimates of the Total (Social) Costs, Average Costs, Marginal Costs and Marginal Externality Costs of road transport-related "accidents" in New Zealand (for both motorised and non-motorised users). This was a component in a wider NZ study on domestic transport costs and charges.
As well as aggregate cost calculations, the analysis considers the various inter-relationships between the funding and charging for costs related to accidents. This includes the roles of the Accident Compensation Corporation (ACC) and private insurance to cover many of the medical, work-interruption, and property damage costs associated with road accidents and other transport mode accidents (otherwise largely borne by individuals, employers and the public health service).
Following a review of the relevant literature and available data, the paper first explores the overall costs associated with road accidents (including pedestrians, cycles, motorcycles, trucks, buses, cars and other light vehicles) in New Zealand, and the average costs per vehicle-km, net tonne-km or person-km where possible. The data indicated an overall annual social cost of $5.6 billion for road accidents involving a motor vehicle and $0.8 billion for non-motorised accidents not involving a motor vehicle.
The next part looks at the marginal costs and charges (i.e. the unit variable costs of changes to the current transport volumes), including differences between urban, rural and motorway situations. It also explores further the payment streams (i.e. who ultimately pays for the costs involved with transport accidents) and makes some recommendations for improvements to existing transport data sources.
An industry question & answer session discussing the findings was also held on 30 August 2022.