Is it possible to have zero traffic deaths in a year? Is it even probable? As it turns out, yes. Here’s an article on what Helsinki did in order to make this a reality:

Andrei, M. (August 1, 2025) “Helsinki went a full year without a traffic death. How did they do it?” ZME Science, https://www.zmescience.com/science/news-science/helsinki-went-a-full-year-without-a-traffic-death-how-did-they-do-it/ [Last accessed: 8/19/2025]

To quote from the article:

“A lot of factors contributed to this, but speed limits are one of the most important,” said Roni Utriainen, a traffic engineer with the city’s Urban Environment Division.

More than half of Helsinki’s streets have a speed limit of 30 km/h (approximately 20 mph). Half a century ago, the city barely had half of its area with a 50 km/h limit (30 mph). They gradually worked to reduce the speed limit, especially around schools and kindergartens.
Smarter street design also played a key role. Pedestrian and cycling infrastructure was prioritized for upgrades in recent years. More and more people started using public transit or bikes, or just walking. Substantial investments also made public transit more efficient and reliable.

“Public transport in Helsinki is excellent, which reduces car use, and with it, the number of serious accidents,” Utriainen noted.
Another key component was bringing the police on board. Helsinki introduced automated traffic cameras and enforcement systems, which also helped bring down reckless driving.”