Vehicle safety tech struggles in bad weather

The latest research from AAA finds that some of the new vehicle technology intended to improve safety may not work in the rain.

The new research finds that moderate to heavy rain affects a vehicle safety system’s ability to “see” and therefore limits the effectiveness of the technology, including automatic emergency braking and lane keeping assistance.

Vehicle safety systems rely on sensors and cameras to see road markings, other cars, pedestrians and other obstacles in the roadway, and those sensors and cameras do not function as well in the rain. It is critical that drivers understand the limits of new technology and remain fully engaged when behind the wheel.

During closed course testing, AAA simulated rainfall and found that test vehicles equipped with automatic emergency braking traveling at 35 mph collided with a stopped vehicle one third (33%) of the time. Lane keeping assistance didn’t fare any better with test vehicles departing their lane 69% of the time.

Automatic emergency braking engaged while approaching a stopped vehicle in the lane ahead:

In aggregate, testing conducted at 25 mph resulted in a collision for 17% of test runs.

In aggregate, testing conducted at 35 mph resulted in a collision for 33% of test runs.

Lane keeping assistance engaged to maintain the vehicle’s lane position:

In aggregate, veered outside of the lane mark- ers 69% of the time.

Vehicle safety systems, also known as advanced driver assistance systems or ADAS, are typically evaluated in ideal operating conditions. However, AAA believes testing standards must incorporate real-world conditions that drivers normally encounter.

Previous AAA testing of vehicle safety systems in both closed-course and real-world settings show that performance is greatly impacted by driving scenarios, road conditions and vehicle design, finding issues like the following:

Struggling to stay within in a marked lane in moderate traffic, on curved roadways and on streets with busy intersections

Failing to stop for pedestrians in common scenarios like crossing in front of a vehicle, a child darting out between two parked vehicles or walking at night

Colliding with a simulated disabled vehicle and instances of coming too close to other vehicles or guardrails

AAA’s research continues to show that vehicle safety system performance varies widely, reinforcing that they are not a replacement for a fully engaged driver.

AAA recognizes these systems have the ability to lessen the chance of a crash and improve the overall safety of driving, but this research, like previous AAA research, illustrates that there is still opportunity for improved performance in real-world scenarios.

It is essential for drivers to be familiar with how their system operates. AAA urges drivers to take time to read the vehicle owner’s manual to learn when, where and how to use them. The vehicle owner’s manual or online materials provided by the automaker are the best resource for understanding the ins and outs of an individual vehicle’s safety system. It will give clear guidance on when and where the system operates best, as well as how to use it properly.