WASHINGTON, D.C. — The U.S. Transportation Department’s National Highway Traffic Safety Administration (NHTSA) said on Wednesday it has finalized rules requiring electronic stability control (ESC) systems on new commercial trucks and large buses.

The regulations require the systems on Class 6-8 trucks plus large buses exceeding 26,000 pounds in gross weight.

Compliance will be evaluated using a “j-turn” test that replicates a curved highway off-ramp.

The rules will take effect for most heavy trucks two years from publication of the regulations while some of the largest buses will have longer to comply.

Canada is expected to adopt similar regulations.

“ESC is a remarkable safety success story, a technology innovation that is already saving lives in passenger cars and light trucks,” said U.S. Transportation Secretary Anthony Foxx. “Requiring ESC on heavy trucks and large buses will bring that safety innovation to the largest vehicles on our highways, increasing safety for drivers and passengers of these vehicles and for all road users.”

ESC works instantly and automatically to maintain directional control in situations where the driver’s own steering and braking cannot be accomplished quickly enough to prevent the crash.

The National Transportation Safety Board in the U.S. has recommended a requirement for ESC on heavy-duty vehicles since 2011.

A rule requiring light-duty vehicles to include ESC took effect in 2012.

“Reducing crashes through ESC in these trucks and buses will save lives, nearly 50 each year. It will move goods and people more efficiently and reduce the toll crashes take on our economy through traffic delays and property damage,” said NHTSA Administrator Mark Rosekind. “It’s a win for the safety and convenience of the traveling public and for our economy.”

NHTSA estimates the rule will prevent as many as 1,759 crashes, 649 injuries and 49 fatalities each year. It also believe ESC will prevent up to 56% of rollover crashes, which defined as a truck rollover not caused by striking an obstacle or leaving the road.

The American Trucking Associations said it welcomed the mandate. 

“Last month, NHTSA reported to Congress that truck rollover and passenger ejection were the greatest threats to truck driver safety,” said ATA Executive Vice President Dave Osiecki. “We can save lives by preventing rollovers with electronic stability control technology, and that’s a positive for our industry. Many fleets have already begun voluntarily utilizing this technology and this new requirement will only speed that process.”