Promoting Walking and Cycling As An Alternative to Using Cars: What Works? a Systematic Review
D Ogilvie, M Egan, V Hamilton, M Petticrew, Medical Research Council, UK
Urban traffic congestion is an increasing problem throughout Europe. One response to this is to discourage the use of private cars and to encourage a shift towards alternative modes of transport. However, the potential benefits of a modal shift are not limited to effects on congestion and the environment. There is increasing interest in the relationships between transport and health. In particular, walking and cycling pose little risk to other road users, and provide opportunities for increasing physical activity which may reduce the risk of heart disease, obesity and diabetes and promote wellbeing.
Promoting a modal shift from using cars towards walking and cycling could therefore help to meet cross-cutting health, transport and environmental policy objectives for cities throughout Europe.
Good evidence of what interventions might be effective in achieving a modal shift is rarely cited. In many areas of health and social policy, the most reliable evidence of the effectiveness of interventions is now considered to be the systematic review, in which a rigorous scientific method is applied to finding, appraising and synthesising evidence.
We carried out a systematic review to address the question: what interventions are effective in promoting a modal shift from using cars towards using physically active modes of transport in urban populations in developed countries?
We sought empirical studies of any design that assessed the effects of any intervention that was applied to a whole urban population or area and for which outcomes were reported in terms of a change in the distribution of transport mode choice. We also sought evidence (where available) about the social distribution of intervention effects and about positive or negative effects on health. We searched 17 electronic databases for published and unpublished literature in any language. We also searched bibliographies, reference lists and websites and contacted experts. We assessed each study for its methodological quality and its relevance to our research question and synthesised the findings.
After screening over 5500 titles and abstracts, we assessed the full text of 390 documents in English, Danish, Dutch, French, German, Norwegian and Swedish. We identified 69 potentially relevant studies and included the 23 most valid studies in our final analysis. These were studies that used a prospective and/or a controlled study design and in which outcomes were assessed in an identifiable local population.
We found evidence about interventions of four main types: ?health promotion? activities, engineering measures, financial incentives, and the provision of alternative services. The best evidence we found in each category was as follows:
?Health promotion? activities ? We found little good evidence that publicity campaigns or school travel co-ordinators were effective in changing behaviour. Some targeted or tailored interventions offered only to households or commuters identified as being ready to change were effective, but the social distribution of their effects is not clear.
Engineering measures ? Improving the connectivity of the cycle route network in one city where cycling was already very popular increased the cycling mode share. We found no evidence of comparable quality from other cities, and no good evidence that traffic restraint schemes on their own were effective.
Financial incentives ? We found no evidence that road user charging was effective. A law requiring workplaces to offer staff financial incentives not to drive to work was associated with a small positive effect.
Alternative services ? Opening a new railway station in one commuter town was followed by a positive modal shift. The evidence we found about telecommuting and car sharing showed that these were ineffective and may even have encouraged car use.
Robust evidence about direct effects on health is rather limited. The best evidence comes from randomised trials concerned with promoting active commuting to work. These showed small increases in certain measures of fitness and general health in the intervention groups. We found no evidence about the effects of a successful modal shift intervention on accident rates or on any other measure of population health.
The available evidence suggests that behaviour change programmes may be effective where they are targeted on receptive subgroups in the target population and involve quite intensive and/or tailored input. The evidence for these targeted interventions is stronger than for those based solely on publicity, engineering, financial and other measures.
However, it may not be possible to apply these targeted interventions to large populations, and we suspect from what we know in other areas of health promotion that they are likely to be taken up most by the healthiest people in the population. We will discuss the implications of these observations for the design of future interventions.
Most existing research in this area is of limited utility for answering the increasingly important question about how transport policies can influence population health, either because of methodological weaknesses or because relevant research questions have not been asked. However, even the limited evidence available raises the possibility that some well-intentioned interventions may be ineffective or even have negative effects. We now need rigorous prospective studies of the effects of transport interventions on the health and health-related behaviour of local populations. We will offer a public health perspective on how such research might be conducted and discuss the potential for collaborative research between transport and health researchers.
Association for European Transport