STOCKHOLM — Across this Scandinavian capital of graceful cyclists and speed-regulating shrubbery, cabbies who drive Volvos and pedestrians who look over their shoulders before jaywalking, a simple figure rules:

Zero. It is the number of people permitted to die in Swedish traffic, according to national law.

For nearly two decades, every rising barrier and reduced speed limit has been tailored to this seemingly impossible goal, of eradicating traffic deaths and serious injuries, and its guiding premise: Every inch of street space must anticipate, and accommodate, human error.

While roadway deaths have not been eliminated, the country’s rate of fatalities has been whittled down to an international low. Now its approach faces perhaps its stiffest test: the streets of New York City.

In a bid to reverse generations of roadway unruliness, Mayor Bill de Blasio has put the strategy, known as Vision Zero, at the forefront of his transportation and policing agendas, targeting 2024 as the first year with no traffic deaths.

But in a city of 800 languages, nearly 14,000 taxis and 8.4 million potential traffic rants, street safety promises to be a complicated import.