A group of New Zealand researchers recently published an excellent paper on the costs and benefits of investing in a complete cycle network and safe street design. Their paper, which is available online, found that:
the benefits of all the intervention policies outweighed the harms, between 6 and 24 times. However, there were order-of-magnitude differences in estimated net benefits among policies. A universal approach to bicycle-friendly infrastructure will likely be required to achieve sufficient growth in bicycle commuting to meet strategic goals.
Our findings suggest that the most effective approach would involve physical segregation on arterial roads (with intersection treatments) and low speed, bicycle-friendly local streets.
We estimate that these changes would bring large benefits to public health over the coming decades, in the tens of dollars for every dollar spent on infrastructure. The greatest benefits accrue from reduced all-cause mortality due to population-level physical inactivity.
The researchers employed a system dynamics modelling approach that incorporated feedback loops between infrastructure provision and street design, people’s travel behaviours, and actual and perceived safety.
As a transport economist, I found their methodology incredibly interesting. It illustrates how you often need complex modelling tools to quantify things that are intuitively quite simple. In this case, the fact that if you make every street safe to cycle on, people will choose to get on their bikes.
Importantly, the researchers found that a larger, more ambitious programme of cycle upgrades will deliver a higher benefit-cost ratio than a smaller programme. This is what economists sometimes call the “complete network” effect – in effect, the more places you can get to easily and safely on a bicycle, the more likely you will be to cycle. (This is also why Facebook has so many users: You have to have an account because everybody else also has an account!)
Right now, Auckland’s obviously not doing too well when it comes to complete cycle networks. If you look at Auckland Transport’s online cycle maps, you’ll see some streets with strips of green paint down the side, and many more that you could in theory cycle on (if you were especially bold).
However, we’re lucky enough to have a local example of a city that is rolling out an ambitious complete cycle network. Since the 2011 Canterbury Earthquakes, Christchurch has planned a network of 13 major cycleways that will extend throughout the city, a re-jig of its city centre street network, and a new street design manual that will deliver better on-road cycle facilities. (Disclaimer: I have previously worked on the An Accessible City project as a consultant.) And they’re planning on getting it done over the next five years.
It’s going to be interesting to watch Christchurch over the next few years. I expect they’ll provide a good example for a lot of other New Zealand cities.