Researchers in this week's BMJ assessed the best available evidence from towns and cities around the world, looking for evidence of measures that had reduced car use, increased walking and cycling, and, if possible, improved the health of the local population into the bargain.
They found that giving targeted advice and support to people who already want to change their behaviour can be effective, but for many other measures that could influence the wider population, the evidence is far from clear yet.
"We see this as a first attempt to map out what the evidence shows and to lay some ground work for further research," say the authors. "A lot of transport research has focused on how to reduce congestion or make the roads safer. These are obviously good things in their own right, but given the current interest in the health benefits of regular physical activity, we wanted to find out how the population can be encouraged to walk and cycle more instead of always taking the car.
"So far, there's remarkably little evidence that measures like traffic calming and publicity campaigns have actually had this effect in practice. That's not to say they couldn't work, of course. It's only recently that walking and cycling have been taken at all seriously in transport planning, and not much research has been done on this topic."