CYCLING INJURY RISK

In last (Wednesday) evening's Evening Standard, and also WF Guardian online, there is reference to a study by Rachel Aldred at the University of Westminster.It can be found here:

It is entitled "Cycling injury risk in London: A case-control study exploring the impact of cycle volumes, motor vehicle volumes, and road characteristics including speed limits".

The paper's own abstract is this:

"Cycling injury risk is an important topic, but few studies explore cycling risk in relation to exposure. This is largely because of a lack of exposure data, in other words how much cycling is done at different locations. This paper helps to fill this gap. It reports a case-control study of cycling injuries in London in 2013–2014, using modelled cyclist flow data alongside datasets covering some characteristics of the London route network. A multilevel binary logistic regression model is used to investigate factors associated with injury risk, comparing injury sites with control sites selected using the modelled flow data. Findings provide support for ‘safety in numbers’: for each increase of a natural logarithmic unit (2.71828) in cycling flows, an 18% decrease in injury odds was found. Conversely, increased motor traffic volume is associated with higher odds of cycling injury, with one logarithmic unit increase associated with a 31% increase in injury odds. Twenty-mile per hour compared with 30mph speed limits were associated with 21% lower injury odds. Residential streets were associated with reduced injury odds, and junctions with substantially higher injury odds. Bus lanes do not affect injury odds once other factors are controlled for. These data suggest that speed limits of 20 mph may reduce cycling injury risk, as may motor traffic reduction. Further, building cycle routes that generate new cycle trips should generate ‘safety in numbers’ benefits."

Assuming the analysis to be as rigorous as most of this abstract suggests, the last sentence of it seems to be a curiously questionable claim. The new cycle trips may benefit the existing trips in terms of safety in numbers, but - if risk while cycling is your yardstick (as distinct from, say, convenience) - the new cyclists will probably be at greater risk than if they continued to do whatever they were previously doing (driving, watching TV .....