Automatic emergency braking is not great at preventing crashes at normal speeds

According to new research from the American Automobile Association, automatic emergency braking is good at preventing low-speed rear-end crashes, but not so good when vehicles travel at more average speeds.

All new cars sold in the US are required to come standard with AEB, which uses forward facing cameras and other sensors to automatically apply the brakes when a crash is imminent. According to the Insurance Institute for Highway Safety, AEB could prevent over 30,000 crashes and 12,000 injuries by the year 2025.

Since first rolling out to production vehicles nearly 20 years ago, AEB has evolved and been put to the test. It wasn't that great.

Greg Brannon, director ofAAA's automotive engineering and industry relations, stated that Automatic Emergency Braking does well at tackling the limited task it was designed to do. The task was drawn up a long time ago and the standards haven't changed.

The limited task it was designed to do did well.

Four vehicles were selected for testing and all of them came with driver-assist features.

T-bone and left turns in front of oncoming vehicles are two more common crash scenarios that AEB can be used to reduce. Forty percent of the total deaths in crashes involving two passenger vehicles in which the striking vehicle did not lose traction or leave the roadway were caused by these two types of crashes.

The results weren't very good. In both the T-bones and left turns, AEB failed to prevent crashes. The system failed to slow the vehicle.

As long as the speed was kept low, AEB did a better job. The system prevented 17 crashes at 30 mph. The impact speed was reduced for the test runs. Six out of 20 rear-end crashes were prevented by AEB at 40 mph. The impact speed was reduced for test runs that ended in a crash.

The shortcoming of automatic braking and other driver assist features has been highlighted before. The group found that AEB was terrible at preventing cars from running over dummies.

The studies will be of interest to the auto industry, which has made eliminating traffic crashes and deaths a priority. The auto industry is being pressured by regulators to do more.