Thursday, September 13, 2012

Road safety - how not to reason from data

My apologies for going quiet over the summer.  I've been in China, and they're not too big on blogs there (blogger is blocked).

Just a short post here, on something fairly obvious.  Here's an extract from post number 51 by Cambridge News' Cycling Blog on speed limits.
In Great Britian in 2011, 7 people were killed on a road with a 20 mph limit. 636 killed in a 30 mph limit. 289 people were seriously injured in a 20 mph limit, 13,168 in a 30 mph limit... Yes, these are large numbers. But it is the proportions that matter here... So that is proof then. Lower speed limits means fewer people killed.
[In case you're wondering, there's no irony in the last sentence.  At all.]  I assume you're all thinking the same as me by now.