1.1 Impact on social cost of deaths and serious injuries

This benefit is about the impact of reducing the number of deaths and serious injuries (DSIs) in all land transport modes, and therefore reducing their social costs.

The social cost of deaths and serious injuries includes the cost to individuals, as well as the cost on the health system and costs due to delays on the network. It reflects the permanent and profound devastation that DSIs have on loved ones, families and whānau, colleagues and workplaces, and communities.

In calculating the monetised social cost, the unit cost of a road crash or a road injury includes loss of life and life quality, loss of output due to temporary incapacitation, medical costs, legal costs, damage to property, and vehicle damage costs. The unit cost is multiplied by the predicted number of crashes. The unit crash cost is varied by vehicle crash type and severity, and the predicted crash number accounts for the road environment and the exposure to the risk of crashing.

Quantitative measures include the number of DSIs, personal and collective risk, and crashes by severity. 

While current measurement is road-centric, this benefit also considers safety relating to rail and active modes.

Investments and programmes that may contribute to this benefit include those delivering specific safety infrastructure, such as median barriers and roundabouts, which are primary safety measures aimed at reducing DSIs. They may also include investment in other improvements where safety unlocks other co-benefits relating to wellbeing, for example mode-shift initiatives. Continuous programmes that maintain or improve safety might also contribute to this benefit.

This benefit impacts not only users of the transport system, but their family and friends who may be impacted by damage to property or personal injury or death.