Across London, 20 mph zones combine a lower speed limit with physical street engineering and camera enforcement to create pockets of safety across the city. According to the British Medical Journal, serious traffic injuries and fatalities have fallen by 46 percent within the zones; 27 fewer Londoners are killed or seriously injured each year because of the zones. Now, street safety advocates are looking to join those neighborhood-sized zones with signage-only 20 mph speed limits on connecting streets.

While the physically calmed zones can be installed by neighborhood-level officials, the new push requires mayoral support. With London holding an election for mayor in May, 2012, street safety activists are hoping to make lower speeds limits a campaign issue. A coalition of public health, environmental, and transportation advocates have launched a letter-writing campaign to each of the mayoral candidates, asking them to commit to instituting a 20 mph speed limit. Though the major-party candidates have not yet signed on, Green Party candidate Jenny Jones, whose party won about three percent of the vote in 2008, has promised to institute 20 mph speed limits if elected.

Here in New York City, our next mayoral elections will take place a year after London’s. The race is already well underway, though. With a crowded field for the Democratic primary, candidates are jostling for support wherever they can find it. So what’s one thing would you ask the New York City mayoral candidates to commit to?