Crash rates for pedestrian crashes of all severities were 27% lower for vehicles equipped with pedestrian automatic emergency braking (AEB) than for unequipped vehicles as long as the vehicles were traveling during daytime or on a well-lit road, a new study from the Insurance Institute for Highway Safety (IIHS) found. 

However, when researchers evaluated pedestrian crashes that occurred at night on roads without streetlights, there was no difference in crash risk for vehicles with and without pedestrian AEB.

The findings indicate that pedestrian AEB systems are much less effective in the dark, where 75% of fatal pedestrian crashes happen.

Pedestrian roadway fatalities are on the rise — increasing 51% since 2009, and the 6,205 pedestrians killed in 2019 accounted for nearly a fifth of all traffic fatalities, notes IIHS. That same year, approximately 76,000 more pedestrians sustained non-fatal injuries in crashes with motor vehicles.

Those statistics speak to why safety systems are so important. Pedestrian AEB systems warn drivers when they’re at risk of hitting a pedestrian and apply the brakes if necessary to avoid or mitigate a crash. The recent study aimed to assess just what kind of impact the technology is having in the real world.

Overall, pedestrian AEB was associated with a 27% reduction in pedestrian crash rates of all severities and a 30% reduction in injury crash rates. However, among a subset of nearly 650 crashes for which detailed information about the lighting conditions, speed limit and configuration of the crash was available, a more complex picture emerged.

Those more detailed results showed that pedestrian AEB reduced the odds of a pedestrian crash by 32% in the daylight and 33% in areas with artificial lighting during dawn, dusk, and nighttime. But in unlighted areas, there was no difference in the odds of a nighttime pedestrian crash for vehicles with and without the crash avoidance technology.

Speed impacted on the effectiveness of the technology as well. For example, pedestrian AEB was associated with a 32% reduction in the odds of a pedestrian crash on roads with speed limits of 25 MPH or less and a 34% reduction on roads with 30-35 MPH limits, but no reduction at all on roads with speed limits of 50 MPH or higher or when the vehicle was turning.