When high-viz clothes make you invisible: reflectors can confuse automatic braking systems
Who’d have thought reflectors of all things could hinder brake assist systems in modern cars? Obviously, this isn’t a reason to stop wearing clothes that make you stand out. But it does pose a blind spot that puts those doing the right thing in danger.
Being inconspicuous like Harry Potter with his invisibility cloak is every child’s dream. It’s also every parent’s nightmare when they send their brightly clad, reflector-festooned children out in the morning with a queasy feeling.
But guardians do all of this with good reason. At nursery age and in the first few years of school, children can’t correctly assess noises and speeds – that’s if they can even see the traffic over the bonnets of parked cars.
The Swiss Council for Accident Prevention (BFU)(site in German) has ascertained that children aren’t fully aware of dangers until the ages of eight to ten. According to their figures, «in 1980, more than 1,700 children were seriously or fatally injured in road accidents, but today this figure is still around 10% of that.» While it’s a lot better, it’s still way too many.
One reason for the drop in accidents is certainly vehicle technology. By the time a person reacts, a lot of damage has usually been done, which modern safety systems can now prevent. Technology can understand, analyse and act on the situation. For example, by braking resolutely if a person steps onto the road unexpectedly. Since July 2024, emergency brake assist systems have been mandatory (site in German) for newly registered vehicles in Switzerland and the EU. But how beneficial are they?
Good performance on lit roads
Autonomous emergency braking systems can reduce the accident rate with pedestrians by 27%, according to data from the Insurance Institute for Highway Safety (IIHS) in its current publication. This American non-profit organisation is financed by car insurers and regularly conducts such studies.
As this positive impact has only been clearly demonstrated in good lighting conditions thus far, the test team is interested in how well emergency braking systems perform in the dark. Notably when the risk of accidents increases. So the IIHS tested three models, a Honda CR-V, Mazda CX-5 and a Subaru Forester, each from 2023 but all equipped with appropriate braking systems.
The cars drove towards a dummy, which was sent across the road from the left or right and in front of the three test vehicles, all travelling at a good 40 km/h. They changed up the conditions: sometimes with, other times without street lighting; some cases with dipped headlights, others with full beam. The test dummy was dressed in different clothing: all black, all white, black with a highly reflective ProViz 360 running jacket, and black with reflective bands.
The dummy was wearing something that looked like this:
Sometimes, the assumption that reflective clothing leads to better results was disturbingly inaccurate.
Surely brake assist would rarely get confused?
Honda’s brake assist failed in all the tests when the dummy was wearing a reflective jacket or high visibility strips. It only reduced speed before the collision by an average of over 50% with dipped headlights, street lighting and when the dummy had white clothing. The test dummy was hit in 46 out of 55 attempts, a rate of 84%.
Similarly, the Mazda didn’t slam on the brakes when the dummy had on reflector strips. Mazda’s brake assist coped slightly better with the running jacket and slowed down by as much as 62%, depending on light conditions. Overall, it was unable to prevent 88% of collisions in 59 attempts.
The Subaru proved it can do much better: in 53 journeys, it only failed to stop in time once. You probably already guessed it: the dummy was wearing reflector strips during that particular attempt.
Source: Wikimedia Commons/Kevauto/CC BY-SA 4.0
This blind spot needs to go
Anyone wearing reflectors to protect themselves while walking or cycling on dark streets is surprisingly ill equipped in this test set-up. Obviously, this is a problem that manufacturers need to address as soon as possible.
Pedestrians, cyclists, and road workers often wear reflective clothing for safety. It’s unacceptable that these measures could inadvertently make them harder for AEB systems to recognize.
You could argue that fluorescent clothing alone should be enough to make drivers aware of the hazard. You can see the difference it makes here:
It goes without saying that we shouldn’t rely on brake assist. But the results still make you feel a bit queasy, because it’s people who seem to be doing everything right that are at risk. We can only hope that manufacturers will take this to heart and eliminate this blind spot.
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Michael Restin
Senior Editor
Michael.Restin@digitecgalaxus.chSimple writer, dad of two. Likes to be on the move, shimmies through everyday family life, juggles with several balls and occasionally drops something. A ball. Or a remark. Or both.
