It is this last category which has been focal in medical and pharmaceutical research and which is of great interest to the transport safety field, especially when considering the introduction of road safety devices or other countermeasures. Thompson, Graham & Zellner (2001) discuss a number of quantitative approaches to deal with this issue.
One approach (QALY) calculates the quality-adjusted life years associated with a certain safety measure. QALYs combine information on duration of life and health-related quality of life into a numerical index. This technique is widely used in the medical field to assess new drugs or medical interventions and could be applied in the road safety field as well.
A slightly different technique, called DALY is promoted by the World Bank and the World Health Association (WHO). DALY also combines information on duration of life and quality of life into a numerical index that can be aggregated across people. The DALY approach evaluates health states in terms of a single dimension, degree of disability, whereas QALY addresses a wide range of dimensions of quality of life. A third approach which has been suggested calculates the Normalised Injury-Fatality Costs (NIC). It is a research-based tool which assumes that all health-state values and preferences are reflected in the actual lifetime costs of medical treatment, ancillary costs (which include costs of permanent partial incapacity) and fatality costs to society. NIC intentionally neglects so-called 'pain and suffering' costs, as these were believed to be subject to enormous variations.
Despontin, Verbeke & Brucker (1997) suggest that decision-makers should approach the issue of road safety countermeasure evaluation in a twodimensional way as illustrated in Table 6.