For every dollar spent to build new separated bike lanes, cities could save as much as $24 thanks to lower health care costs and less pollution and traffic, according to a new study from researchers in New Zealand.

“At the moment in most car-dominated cities, it’s easy to justify spending transport money on new roads as a response to increasing car use, despite the negative impacts this has on the environment and people’s health now and in the future,” says lead author Alexandra Macmillan. “We wanted to explore some policy choices that were realistic, affordable, transformative and healthy.”





While there’s already research backing up the facts that biking makes us happier, more energetic, better able to concentrate, less fat, and generally healthier–and that bike lanes make more people ride, and even boost local business–this study may be the first to look at how different types of bike infrastructure investments pay cities back later.

The researchers looked at Auckland, New Zealand, which is currently not a particularly bike-friendly place, and used computer simulations to model different scenarios for new bike-related investments, including regular bike lanes, lanes shared with buses, and fully separated lanes.

They found huge differences: If the city built a network of separated lanes and slowed down traffic speeds, it could increase cycling by 40% by 2040, but adding a few lanes in a few places might only increase bike traffic by 5%. The more people ride, the more the cost savings would add up for Auckland–the biggest factor being a reduction in health care costs. A smaller investment would have little impact at all; the city is so bike-unfriendly that major changes are needed.





In cities dominated by cars, a small increase in cycling tends to lead to more biking injuries and deaths, making other people more afraid to ride. The way to overcome that problem, the researchers found, is to make a bigger commitment to better bike lanes.

“We found that significant infrastructure investment is needed to overcome this dampening effect of fears about cycling safety; that high quality changes to main roads and local streets are the best place to start for cities with low cycling and high car use; and that these investments can have benefits an order of magnitude greater than the costs if you get them right,” says MacMillan.