Interesting piece by Hayley Birch for The Guardian:

Implicit in all of this is the idea that 20mph speed limits actually work. To reduce casualties they have to reduce speed, but not everyone agrees that they do. Asked whether he thinks Islington’s 20mph speed limits have made any difference, Aidan Farrow, a member of Islington Cycling Club who cycles thousands of miles on the roads every year, says he doesn’t think so. “My experience is that they’re ignored by many drivers,” he says. “I don’t think they’re enforced and I don’t think that drivers realise they’re there a lot of the time.”

Long story short: 20mph zones would be great for improving safety but in reality, most drivers don’t actually respect the speed limit so they’re pretty much useless.

Madrid is a living example of this problem: over the past year many streets in the city have been fitted with 20mph lanes where cyclists have preference, but the reality is that they’ve done very little to improve the situation. Most drivers simply ignore the 20mph signs completely, using those new lanes as if they were regular lanes. Unless the city is willing to start handing out tickets for these infractions, there’s little hope for meaningful change to occur anytime soon.

Via Taras Grescoe.