Pedestrians and traffic, reflected in a mirror, make their way down 14th St. NW on a rainy morning in Washington. (Michael Robinson Chavez/The Washington Post)

Jurisdictions across the United States, including those in the Washington region, are embracing lower speed limits as the key to reversing the recent rise in traffic fatalities.

Their efforts include lowering default speed limits and those in major corridors, and creating slow-driving zones in areas with heavy pedestrian traffic.

Lowering speeds is a fundamental strategy for communities that are part of “Vision Zero,” a program aimed at eliminating traffic fatalities and serious injuries. Locally, the District, Alexandria and Montgomery County have taken the “zero” pledge, joining a growing number of cities that have made the commitment in areas where drivers are increasingly sharing the road with bicyclists and pedestrians. New York, Boston and Seattle are among cities nationwide that have adopted the program.

Officials in the jurisdictions say prioritizing safety over speed or convenience is crucial to meeting their goal. According to research, if a vehicle hits a pedestrian while traveling at 20 mph, the victim has a more than 90 percent chance of surviving. But if the vehicle is traveling 50 mph, the survival likelihood drops to 25 percent.

“We know it’s the speed that kills,” said Leah Shahum, founder of the Vision Zero Network, a campaign supporting cities that have adopted the approach. “People make mistakes; humans are fallible. There will still be traffic crashes. But if they do so at a lower speed, the likelihood of walking away with a broken ankle or an injury that is survivable is dramatically greater than if there is high speed involved.”

The recent uptick in traffic fatalities after a years-long decline, combined with the disproportionate number of pedestrians and bicyclists being killed in the crashes, has added a sense of urgency to the mission, officials say.

Road deaths in the United States increased 6 percent in 2016, reaching more than 40,000 for the first time in a decade, according to a recent report by the National Safety Council. Traffic fatalities had been declining significantly since the 1970s as a result of safer vehicles and increased enforcement of laws on drunken and impaired driving and the use of seat belts.

[Traffic deaths soared past 40,000 last year for the first time in a decade]

Researchers attribute the recent increase mostly to the improved economy and lower gas prices, which have led to more people driving for work and pleasure. In the Washington area, the increases have not been as dramatic as those nationwide, but officials are concerned about the growing number of deaths involving pedestrians and cyclists.

The District has committed to end traffic-related deaths by 2024, with a plan that lowers the default speed limit to 20 mph from 25 on some neighborhood streets and creating 15 mph zones from 7 a.m. to 11 p.m. on roadways around schools, parks, and senior and youth centers. The city also has proposed raising the penalty for excessive speeding to $500.

Montgomery County is pressing the state to allow it to cut the default speed limit to 25 mph from 30 and lower the limit in some neighborhoods to 20 mph.

Alexandria lowered the default speed limit in some neighborhoods by 10 mph last year to 25, and the city is studying reducing speed limits in areas where speed is consistently a factor in crashes.

“The faster you are going over 20 miles per hour, the more likely the person that you hit is going to die. There is no question that reducing speed improves safety,” said Michael Farrell, a senior transportation planner at the Metropolitan Washington Council of Governments. “The message out there is to slow down.”

But the approach is not without critics. Some say cities are using traffic data to justify raking in millions in traffic fines. Others contend that the proposals go too far, arguing that lowering speeds too much has a significant impact on travel times. Why, for example, set a 15 mph limit around schools when the facilities are closed, they say.

John Townsend, a spokesman for AAA Mid-Atlantic, said lower speed limits could lead to unsafe lane changes and more crashes as motorists try to get around ­slower-moving vehicles. Drivers also fear, he said, that further reductions to the posted speed limits “will engender the proliferation of speed cameras,” and turn city roads into “speed traps.”

In the District, where officials have proposed new and significantly higher fines for a variety of traffic offenses as part of the city’s Vision Zero plan, public backlash stalled the plan for a year. Critics accuse the city of waging war on drivers.

City officials say the goal is to protect all road users. In 2015, 15 of the 26 people killed in traffic crashes were pedestrians, data shows. The number of pedestrians killed last year decreased to nine, but there were more total fatalities, at 28. In many of the cases, authorities say, speed was a factor.

[D.C. plans to add more traffic cameras]

Vision Zero cities also are redesigning roads built for motor vehicles to make them safer for other users. The District, for example, has reduced some lanes to add protected bike lanes, and it has widened some sidewalks. District officials also are pushing for more automated enforcement to target traffic violators, chiefly speeders.

The city operates 171 traffic cameras, according to D.C. police: 107 that monitor speed, 48 to catch red-light runners, eight at stop signs, and eight to detect vehicles that are above size and weight limits. The original Vision Zero action plan called for the deployment of up to 100 additional cameras by October 2017, though officials later said the mayor’s final plan would not specify a number.

Advocates say the strategies work. Two decades after launching its Vision Zero initiative, Sweden is known to have the world’s safest roads. And there is growing evidence that the movement has had a positive impact in the three years since it started in the United States.

In New York, the first city to adopt the program, traffic deaths declined for three consecutive years, down 23 percent overall, according to city data. The program is in use in about two dozen cities nationwide.

Locally, Alexandria and Montgomery are just starting to hash out detailed strategies on enforcement, public education, street engineering and data collection. In the District, two years after Mayor Muriel E. Bowser (D) announced the city’s commitment, a two-year action plan spelled out goals to create safe streets, protect vulnerable road users and prevent dangerous driving. A year after that plan was released, however, it’s unclear how many of the deadlines have been met. The annual progress report that was due in October won’t be released for another few weeks, city officials said.

A national strategy on highway safety, “Toward Zero Deaths,” was rolled out in 2015. Washington-area jurisdictions have supported a regional campaign that promotes road safety. In some jurisdictions, authorities have gotten creative — for example, sending police officers dressed like homeless people out to catch people texting while driving.

“But there is more that we can do,” Montgomery County Council President Roger Berliner said a year ago when announcing the county’s “zero” pledge. “It is time to stop thinking of these fatalities as accidents. These are crashes that we can and must act to prevent. We must say to us, zero is our goal.”

[15 mph speed limit might be coming to a D.C. street near you]

Long-term success, officials say, requires cities to commit earnestly to the goal, using data to drive changes in policy and emphasizing education and enforcement.

“We know that not everyone understands why we do make these changes,” said Yon Lambert, Alexandria’s transportation chief. But they are part of the shift from thinking that traffic fatalities are unavoidable tragedies. Vision Zero may not eradicate all crashes, but it can help cut down on the deadly ones, he said.

“We know that we have a lot of work to get there,” he said.