Salt Lake City's lower speed limits could save lives

• Research shows the risk of serious injury or death drops majorly for pedestrians hit by cars traveling 20 mph versus 25 mph.

Driving the news: Salt Lake City began posting speed limit signs of 20 mph on streets that were previously at 25 mph.

• About 70% of Salt Lake's streets will be affected.

Zoom out: In England, lower speed limits have been promoted for many years — and have been effective in some cities.

• Cities like Bristol and London saw traffic injuries drop anywhere from 19% to more than 60% in connection with speed limit reductions to 20 mph.

Reality check: People didn't actually drive much slower on most of the roads where the speed limit was reduced, according to a national study in the U.K.

• Yes, but: A lot of those case studies were in places that only tested lower speed limits in individual neighborhoods rather than whole cities.

Drivers' behavior appears to change more if speed limits are reduced across a large area, like Salt Lake City's plan.

• Portland, Ore., saw less speeding after reducing residential limits to 20 mph.

Context: So far this year, cars have killed at least 44 Utahns who were on foot or cycling, plus four on "personal conveyance" devices like wheelchairs or scooters.

• That total was just 24 at this time last year.
• In 2015, 54 cyclists and pedestrians were killed in traffic for the entire year — and that's Utah's highest death toll in the past decade.

What's next: Crews will install 575 new "Speed limit 20" signs around the city.

What the city is watching: If you see the new, lower speed limit sign in your neighborhood, take a picture and let SLC know!