WASHINGTON — Federal regulators are proposing to require that manufacturers equip large trucks and buses with safety systems that help prevent rollover accidents.

The National Highway Traffic Safety Administration proposal to require electronic stability control in new buses and trucks was published online today.

When the safety system detects a loss of steering, it automatically applies the brakes to help steer the vehicle in the direction the driver intends to go. Braking is applied individually to wheels to counter over-steering and under-steering.

Government research shows the technology could prevent up to 56 percent of rollover crashes each year — the deadliest among all crash types — and another 14 percent of loss-of-control crashes.

The safety systems are already required in passenger cars, sport utility vehicles and light trucks.