Could a simple front brake light save lives at intersections?

Picture yourself approaching a busy intersection. Cars are zipping past, bicycles weave through gaps, and a pedestrian edges nervously toward the crosswalk. One of the hardest parts of navigating this moment is guessing what the other drivers are about to do. Is that car slowing down? Are they stopping, or will they dart into the junction?

Now imagine if every car had a small green light on the front bumper that flicked on whenever the driver hit the brakes. Suddenly, you wouldn’t need to guess. You’d know instantly: that car is slowing, and you can react accordingly.

This is exactly the idea behind the Front Brake Light (FBL), a simple, retrofit system that could help prevent crashes at intersections. And according to a study published in Vehicles by researchers Ernst Tomasch (TU Graz, Austria), Bernhard Kirschbaum (Comenius University, Slovakia), and Wolfgang Schubert (Bonn Institute for Legal and Traffic Psychology, Germany), it might actually work.

Intersections are the traffic equivalent of chaos theory. Most accidents don’t happen on long, straight highways where everyone is moving in the same direction. Instead, they cluster where paths cross: at crossroads, roundabouts, and T-junctions.

In Austria, for example (where this study is based), just three types of intersection crashes, cars turning across oncoming traffic, cars colliding while crossing paths, and cars turning left into the path of another, account for more than 80% of serious and fatal junction accidents.

Safety technology has advanced dramatically since the first anti-lock braking systems appeared in the 1970s. Modern cars now come with automatic emergency braking, forward collision warnings, and lane departure alerts. These systems save lives, but it takes decades before an entire vehicle fleet is replaced. Not everyone drives a shiny new car with the latest safety package. That’s where retrofittable systems like the FBL come in. Instead of waiting for the future of fully automated vehicles, could we save lives with a clever add-on today?

The Front Brake Light isn’t a brand-new concept. In fact, researchers first tested it in the 1970s. Back then, the results were promising: people liked the idea, and both drivers and pedestrians felt it made traffic safer. But after that, the idea gathered dust.

It wasn’t until the 2010s that researchers in Germany revisited the concept. In controlled lab studies, pedestrians could identify when a car was braking more quickly if it had an FBL. Later, trials at Berlin’s former Tegel Airport and in Slovakian cities put thousands of FBL-equipped cars, buses, and trucks into real traffic. Drivers overwhelmingly reported that the system made road interactions smoother and safer.

Still, those studies focused mostly on perception and driver attitudes, not on whether the FBL could actually prevent accidents. That’s the gap the new research aimed to fill.

Since no commercial cars are currently sold with FBLs, the researchers couldn’t simply pull crash statistics from national databases. Instead, they used a method called counterfactual simulation, essentially a giant “what if” experiment.

Here’s how it worked. They started with 200 real intersection crashes from Austria, drawn from a detailed accident database. Then, using reconstruction software, they recreated each crash step by step: who moved where, at what speed, when brakes were hit. Subsequently, they ran the same crash again, but this time, they imagined the “non-priority” car (the one breaking the rules or entering incorrectly) had a front brake light. Finally, they asked: would the driver of the other car have had time to react differently if they’d seen that FBL signal?

This approach let them test the FBL against a wide variety of crash scenarios, from cars pulling out of side streets to left-turn collisions, without waiting for years of real-world adoption.

The results were encouraging. In fact, Up to 17% of crashes could have been completely avoided with an FBL, depending on how quickly drivers reacted. Another 9–25% of crashes could have been less severe, with reduced collision speeds. If visibility of the FBL was good (for example, when cars were facing each other head-on rather than at sharp angles), the benefits were even greater: as many as 26% of crashes might be avoided, and nearly 40% mitigated. Reaction time mattered a lot. With lightning-fast reactions (half a second), drivers could avoid far more crashes. With slower reactions (1.5 seconds), benefits dropped, but the FBL still helped. The system worked just as well in cities as in rural areas. It was slightly less effective in bad weather (rain or snow) but still offered measurable improvements.

In plain terms: if widely adopted, a simple light on the front of cars could make a meaningful dent in one of the most dangerous categories of crashes.

At first glance, it seems almost too obvious. Why would a front-facing brake light make such a difference? Well, the answer lies in human reaction time. On average, it takes drivers more than a second to notice and respond to unexpected hazards. But when we’re given a clear, early cue, like a glowing light that says “this car is braking”, we can shave crucial fractions of a second off that response.

Those fractions matter. A car traveling 50 km/h (about 30 mph) covers almost 14 meters in one second. Reacting even half a second sooner can be the difference between stopping safely and a devastating collision.

The FBL essentially works as a form of non-verbal communication between drivers. Just as a cyclist makes eye contact before crossing a lane, the light gives others insight into what the driver intends. In the unpredictable chaos of intersections, that extra signal could save lives.

One of the most striking aspects of this research is its practicality. Unlike futuristic autonomous driving systems, the FBL is cheap, simple, and retrofittable. It doesn’t require new infrastructure, satellites, or artificial intelligence. It’s just a light wired to the brake pedal.

And yet, the social science side is equally important. Earlier studies found that most drivers and pedestrians liked the FBL. In trials across Slovakia, more than three-quarters of road users said they’d support making it standard on all cars. That kind of public acceptance is rare in traffic safety, seat belts and speed limits, for instance, faced decades of resistance.

So, where do we go from here?

Of course, not every crash type benefits equally. In side-impact crashes where cars meet at sharp angles, the FBL might not even be visible. In nearly 40% of the studied crashes, the light wouldn’t have been seen by the other driver. Weather, urban lighting, and background distractions could also reduce effectiveness.

Still, the numbers are hard to ignore. If regulators required FBLs on new cars, or even encouraged retrofits on older vehicles, thousands of lives could be saved over the long term.

The authors note that mandatory adoption, similar to how rear brake lights or seat belts became standard, could be a game-changer. Euro NCAP (Europe’s vehicle safety assessment program) already evaluates braking systems at junctions. An FBL could slot naturally into such frameworks.

It’s tempting to think road safety requires moonshot innovations: self-driving cars, radar sensors, vehicle-to-vehicle communication. But sometimes, the most effective solutions are also the simplest.

The front brake light doesn’t replace high-tech driver-assistance systems. But while we wait for the global car fleet to modernize, a process that takes decades, it could act as a bridge technology, making intersections safer today. The FBL is not a silver bullet. But it could be a low-cost, high-impact addition to the safety toolbox. And when it comes to traffic crashes, where milliseconds matter and human lives are at stake, that’s worth serious consideration.

If you want to learn more, read the original article titled "Assessment of the Potential of a Front Brake Light to Prevent Crashes and Mitigate the Consequences of Crashes at Junctions" on Vehicles at http://dx.doi.org/10.3390/vehicles7020040.