Last year turned out to be a banner one for traffic safety in San Francisco and New York, two leaders in the Vision Zero movement to eliminate all traffic-related fatalities. Both cities saw fewer traffic deaths in 2017 than at any point on record.

Vision Zero sets the goal of eliminating all traffic deaths -- whether they are of drivers, passengers, cyclists or pedestrians. The novelty of the movement may be more in its approach than its goal: Vision Zero starts with the premise that humans make mistakes, but road infrastructure ought to account for that. Its champions stress making changes to the physical aspects of streets and sidewalks to reduce vehicle speeds.

The newest numbers boost the case that Vision Zero is working in those cities, because, nationally, the number of traffic deaths has risen more than 13 percent since 2013 when New York and San Francisco adopted the policy.

New York Mayor Bill de Blasio touted his city’s success in a press conference on Monday. The number of pedestrian deaths last year decreased by 32 percent from 2016, while overall traffic fatalities dropped by 7 percent. The city says the 214 deaths is the lowest since New York started tallying traffic-related deaths in 1910.

De Blasio credited the success to a number of changes the city has made in the past few years.

“Vision Zero is working. The lower speed limit, increased enforcement and safer street designs are all building on each other to keep New Yorkers safe. Now we must deepen this work. Not even a single tragedy on our streets is acceptable, and we’ll keep fighting every day to protect our people,” de Blasio said.

In San Francisco, only 20 people died in traffic in 2017. That was a drop from 30 fatalities in 2016 and the lowest number since records started being kept in 1915.

Although we had fewer fatalities on our streets last year, we have more improvements to make before we reach our goal of #VisionZero pic.twitter.com/IbSlbXGf1H — London Breed (@LondonBreed) January 4, 2018

New York and San Francisco were among the first U.S. cities to adopt the Vision Zero traffic safety approach. Dozens of other cities have since followed in their footsteps, but many of them have not seen the same drops in traffic deaths. New York and San Francisco have both made especially significant and widespread improvements to the physical infrastructure of their streets.

New York City says it completed 114 street safety engineering projects in 2017, more than double the pre-Vision Zero annual average. That brings the total number of safety improvements added since the start of Vision Zero to 350.

San Francisco, meanwhile, added 700 improvement projects last year on city streets, including sidewalk bulb-outs, speed humps and signal upgrades, according to KTVU.

Although the overall numbers were encouraging, the numbers in New York, in particular, also raised some worries.

While pedestrian deaths are down, deaths among cyclists, motorcyclists and people in motor vehicles all actually increased from 2016 to 2017. Twenty-three people on bicycles died in New York in 2017, nearly double the 12 who died in 2013.