Drivers who cruise through the residential areas of Portland will soon have to drive slower.

Portland city commissioners overwhelmingly approved an ordinance to reduce speeds in residential zones from 25 mph to 20 mph.

Residential streets make up 70 percent of Portland’s transportation network, and signage is expected to be installed citywide by April 1 this year.

Introduced by Commissioner Dan Saltzman, who oversees the Bureau of Transportation, the plan is part of the city’s Vision Zero goal to reduce traffic-related deaths on Portland roads to zero by 2025.

“Excessive speed is one of the major factors contributing to traffic deaths,” Saltzman said. “From our research, we knew that if we could get Portlanders to slow down, we could save lives.”

Capt. Mike Crebs with the Portland Police Bureau’s traffic division said he supported the ordinance, adding that the ordinance will prevent deaths. Crebs told city commissioners that it takes 59 feet to stop when driving 25 mph, and that it takes 42 feet to stop when going 20 mph — the entire length of a car.

Crebs said Portland Police enforcement of residential zone speeds will remain the same.

“I feel confident that this will prevent somebody from either getting killed or seriously injured,” he said.