Those White Traffic Lights You May See On Some Roads Aren’t Meant For You

If you are in your car, driving through an intersection with traffic lights, you’re accustomed to looking for a few types of signals — usually green, yellow, and red lights or turn arrows. These long-established traffic signals and their colors are second nature for motorists, so when drivers see a traffic light color or pattern out of the ordinary, it can be very confusing, throwing off our familiar patterns.

In recent years, drivers in certain cities may have noticed a separate signal housing on certain traffic lights. This housing displays a white bar that operates independently of the existing lights. Is this some sort of new traffic rule for cars to follow? Nope. Though visible to everyone, the white signals are not for normal motorists or pedestrians; instead, they’re specifically for buses.

The signals are part of an increasingly common, automated Transit Signal Priority system that gives buses the right-of-way at busy intersections. The goal is to avoid buses being held up in normal traffic, helping to speed up transit times for riders while also reducing emissions by reducing the time buses spend idling in traffic. When properly implemented, the signals are just one of the tools that can help bridge the gap between road-going buses and other, more streamlined forms of mass transit. 

Traditionally, one of the biggest issues with buses as a form of urban transit is that they generally use the same streets as normal cars. While a train or subway operates on its own tracks, buses can be just as susceptible to traffic gridlock and crowded streets as any other vehicle. All of this comes on top of other rules that can impede their travel times, of course, like mandated stops at every railroad crossing. 

In some urban areas, buses can use their own designated lanes in traffic, which helps speed things up. When they come to intersections, though, they usually have to stop and follow the same signals and traffic flow as every other vehicle. That’s where the white bus signal lights come in.

These separate bus signals, sometimes referred to as “queue jump” lights, have sensors that detect approaching buses and send a signal to the traffic light. When this happens, the white bar in the light moves from horizontal to vertical, signaling to the driver that they can cross the intersection, all while the other lights remain red.

While the bus priority signal system is relatively simple, you can’t just add these signals to any busy intersection and immediately speed up transit times. To work properly and avoid entanglements with normal traffic, the signals need to be used in areas with designated bus lanes. Otherwise, even if given the right-of-way, buses could still be held up by stopped traffic. Some cities have implemented alternative forms of signal priority systems that detect the approach of buses and emergency services, but instead show a green light without dedicated signals or designated bus lanes.

When the white bus signals first debuted, motorists weren’t just confused by the new, unfamiliar white lights themselves. News reports of the time relayed how some drivers would complain after observing city buses seemingly blowing through red lights — only to be told by bus drivers that they were actually following the new, bus-only signal system.

While this signal system might confuse some unfamiliar motorists and observers, the results so far have been positive. They might take some getting used to, but they’re much more benign than the controversial AI technology New York City adopted in 2025, where city buses can use cameras to autonomously issue traffic tickets to cars parking or driving in bus lanes.