The US government will require automatic emergency braking systems in all new cars starting in 2029. In practice, the new regulation won’t change much – most new cars sold in 2024 will already be equipped with it.
But it could be the start of a government effort to get the auto industry to improve technology, which can be wildly inconsistent and doesn’t live up to advertising claims.
Related: What is automatic emergency braking?
The National Highway Traffic Safety Administration (NHTSA), the government agency most responsible for regulating cars, said Monday that the rule will “save at least 360 lives per year and prevent at least 24,000 injuries per year.”
Automatic emergency braking is already common
Automatic emergency braking systems detect an object in a car’s path and apply the brakes to avoid an accident. Early versions of the technology were able to avoid a collision with a stationary car. Newer versions are designed to detect smaller objects.
The systems attempt to bring a car to a complete stop to prevent an accident. If they fail to do this, they can still slow the car, drastically reducing the severity of the collision.
Automakers now market them with names like “automatic emergency braking with pedestrian detection” and claim they won’t hit cyclists and pedestrians.
They used to only be common on luxury cars. Almost all automakers have signed a pledge promising to include them by September 1, 2022, and they have largely kept their word.
These days they can be found on almost every new car for sale. Even the Nissan Versa and Mitsubishi Mirage – the lowest-priced cars built this year – included versions of the system as standard equipment.
There are now versions of more expensive vehicles that are designed for use in curves or in reverse gear and that detect quickly crossing traffic, such as the one you see when you back out of the driveway onto the street.
But systems don’t always work as they should
Automatic emergency braking makes driving safer. Studies have found that widespread use has halved the number of accidents, saved lives and prevented property damage.
But the technology often does not live up to its marketing.
It works best at low speeds, and we don’t limit our driving to low speeds. An insurance industry safety lab recently began testing the systems above 25 miles per hour. In two rounds of testing, the results were disappointing.
On one lap, no one in a group of midsize SUVs managed to even brake when a simulated car crossed their path. In another case, most compact SUVs encountered a stationary motorcycle in their lane, even though the best systems tested braked to reduce the severity of a collision.
Other tests have shown that the systems are significantly less effective at night.
A recent round of testing found that automatic emergency braking is even less reliable in reverse gear. Insurance industry workers tested four small SUVs to see if they could avoid crossing traffic behind them. Four failed ten times out of ten and one failed nine times out of ten.
However, most systems provided an audible warning that could prompt the driver to brake more effectively than the system alone could.
Mandate means rules of effectiveness
If the automotive industry has already made the equipment standard in practice, why bother with a mandate?
Because once they are required, regulators can require them to be effective.
“The new standard requires all cars to be able to stop up to 62 miles per hour and avoid contact with a vehicle in front,” NHTSA says. Cars must also “detect pedestrians in both daylight and darkness.” In addition, the standard requires the system to automatically brake up to a speed of 150 km/h if a collision with a vehicle in front is imminent and up to a speed of 72 km/h if a pedestrian is detected.”
Testing conducted by watchdog groups raises doubts that many of today’s systems could pass these tests.
A mandate could force the industry to improve it.