If You See a Traffic Light With a Yellow Border, Here’s What It Means

Traffic lights are something drivers encounter almost every day. And even though they’ve been looked at countless times, most drivers barely even notice some of the subtle details about them.

One detail that stands out at some intersections is a bright yellow border around the traffic lights. It’s a small change to a familiar piece of road equipment, and it can make a difference at busy intersections. Learn what the borders do and why they’re not on every traffic light.

What Do Yellow Reflective Borders Around Traffic Lights Mean?

The yellow borders around traffic lights are strips of reflective material attached to a black panel called a backplate. Much like reflective road signs, they catch vehicle headlights and help drivers spot traffic signals at night. The black background also makes the colored lights easier to see against bright skies and nearby buildings.

“This treatment is recognized as a human factors enhancement of traffic signal visibility, conspicuity, and orientation for both older and color vision deficient drivers,” according to the Federal Highway Administration (FHWA).

The borders also help drivers recognize intersections during power outages.

“This countermeasure is also advantageous during periods of power outages when the signals would otherwise be dark, providing a visible cue for motorists to stop at the intersection ahead,” according to the FHWA.

Research suggests the borders can improve road safety. A 2005 study found that adding yellow reflective borders reduced crashes at the intersections researchers examined. The FHWA now recognizes them as a proven safety measure. However, the borders don’t change how traffic lights operate or how long each light stays on. Drivers still need to follow normal traffic rules, including when a signal stops working.

Why Do Some Traffic Lights Have Yellow Borders While Others Don’t?

Federal traffic safety standards allow yellow reflective borders, but don’t require them at every intersection. State and local transportation agencies generally decide where to install them. Some intersections may need better visibility because of glare, nearby buildings, or poor lighting. Transportation agencies may also add reflective borders when installing new signals or upgrading existing equipment.

Cost can influence those decisions, too. Adding reflective strips to an existing backplate is relatively simple, but installing a new backplate may require additional support. That’s why two intersections along the same road might have different traffic lights. The lack of a yellow border doesn’t necessarily mean a signal is unsafe.

Sources

• Federal Highway Administration, “Backplates with Retroreflective Borders”
• Federal Highway Administration, “Manual on Uniform Traffic Control Devices, 11th Edition with Revision 1, Section 4D.06”
• Federal Highway Administration, “Crash Modification Factors Clearinghouse: Safety Impact of Increased Traffic Signal Backboards Conspicuity, Sayed, Leur, and Pump”

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