Promoting Health Preventing Disease

Preventing road-related injuries 197
police patrols to identify alcohol impaired drivers in significantly reducing
accidents and fatalities, although reviews suggest some beneficial effects
(Goss et al. 2008). There is also insufficient information on the effectiveness
of employers screening employees who drive for a living for alcohol or drugs
(Cashman et al. 2009).
There are, of course, measures targeted at other harmful behaviours that
can improve safety on the roads. Driving after drinking alcohol substantially
increases the chance of a traffic crash. Restrictions on alcohol consumption
discussed by Peter Anderson in this volume highlight a wide range of effective
interventions to reduce harmful alcohol consumption. For example, in the United
States experiments looking at the impact of raising the minimum legal drinking
age to 21 in different states have been associated with a 19 per cent reduction
in the risk of road- related fatalities in young adults (Shults et al. 2001), while a
reduction in the minimum legal age in New Zealand for purchasing alcohol has
been associated with a significant rise in crashes and deaths (Kypri et al. 2006).
There is also evidence that helmets reduce the risk of head injuries and
deaths in cyclists and motorcyclists (Thompson et al. 2000; Liu et al. 2008).
Mandatory legislation for helmets for children in the United States has also
been associated with reduced rates of injury (Macpherson and Spinks 2008),
while non- legislative approaches such as community campaigns can increase
the use of cycle helmets by children (Owen et al. 2011).
Some ineffective interventions are also highlighted in reviews. These include
school- based driver education (Roberts and Kwan 2001), which may actually
have adverse effects by reducing the age at which people begin driving, as well
as post- licence driver education programmes (Ker et al. 2005). Evaluations of
some interventions have looked at immediate changes in behaviours, but do
not say anything about long- term impacts on injury such as pedestrian safety
education for children (Duperrex et al. 2002). Measures to improve the visibility
of cyclists and pedestrians do improve detection by drivers, but no work has
been done to look at their impact on accidents (Kwan and Mapstone 2006). No
robust trials on vision screening of drivers were found in one recent review
(Desapriya et al. 2011).
What do we know about cost- effectiveness?
There is a long- standing literature on the economic impacts of investing in road
safety measures with many estimates of different interventions (Elvik 2003).
We cannot report all of these economic studies here, but instead highlight
findings of some studies illustrating the potential cost- effectiveness of different
interventions. In doing so, it is important to remember that most effective road
safety strategies involve a combination of measures rather than individual
measures in isolation; their cost- effectiveness, in combination, may therefore
also be somewhat different. Moreover, many interventions we discuss below
depend very much on behaviour modification and compliance with laws and
regulations, which may differ substantially across cultures. There will also
be issues concerned with infrastructure and the absolute cost of scaling up
services. We will return to these issues later in the chapter.