Los Angeles is a car town, so it's controversial to promote "road diets," a form of roadway reconfiguration intended to slow cars and reduce collisions, especially with cyclists and pedestrians. Scientists reviewed data from one controversial road diet and found that crashes were cut in half, and unsafe speed crashes dropped to zero.
The Rowena Avenue road diet was hotly contested, but average speeds dropped from 39 miles an hour to 35, which is the posted speed limit. That may not sound like a lot, but it is if you're a cyclist or pedestrian. According to the American Automobile Association's Foundation for Traffic Safety, if you get hit by a vehicle going 23 miles an hour, you have a 10% chance of dying. At 42 mph, that jumps to a fifty-fifty chance you'll die. Road diets reduce what engineers call "conflict points," or places where vehicles are most likely to hit something. On a four-lane road, left turns have six: getting rear-ended while making a right or left turn, sideswiping a vehicle while changing lanes to avoid a right or left turn, and crossing two lanes of oncoming traffic. A road diet that incorporates a left turn lane cuts conflict points in half.
The Rowena Avenue diet was helped greatly by 11-year-old Mattlock Grossman, who described the dangers and abuse he endured while trying to ride his bike in his neighborhood.
There's a wealth of previous data that corroborates the Rowena finding. The Federal Highway Administration published a 72-page overview on the conceptualization and execution of road diet strategies.
When I lived in Chicago, I didn't own a car and biked everywhere, but Los Angeles still feels too dangerous for riding a bike. In 2010 Los Angeles Mayor Antonio Villaraigosa was struck by a taxi and broke his elbow while biking. That incident made politicians start taking complaints from cyclists and pedestrian advocates more seriously. Given Southern California's weather, it's the perfect place for bike-friendly roadways, but visiting the comment section of any discussion of road diets, will bring out motorists who despise bicyclists, even if they are going the speed limit.
Mattlock's testimony had to disable comments because of the abuse he was receiving on YouTube, echoing the abuse hurled at him by passing motorists.
• Data scientists say controversial Rowena 'road diet' actually worked (Curbed LA)
• Read more about the project from the study's authors at The Los Angeles Times.