Walk into almost any factory, hospital, office, or warehouse, and you’ll likely encounter tier boards with a familiar set of colors: green, yellow, and red. Green means good. Red means bad. And yellow? Well, it has… some issues.

I began thinking about this after a discussion with my good friend and lean thought leader Billy Ray Taylor. He’s a crusader against the color yellow in visual management. His position is surprisingly simple: There’s no such thing as “almost standard.” A process is either operating to standard or it isn’t. Green means standard. Red means off-standard. Everything else, he argues, is an invitation to debate.

At first, I wasn’t convinced. Like many lean practitioners, I’ve spent years seeing yellow used as an intermediate condition. While working at a factory recently with Billy Ray, I even found myself defending it. “If they’re getting close to the goal,” I suggested, “why not make the metric yellow? It might encourage the team to push just a little harder to get to green.” Billy Ray smiled before replying, “Or yellow becomes the new green.” The room became quiet. His point was simple but profound. Once people begin viewing yellow as acceptable, they stop striving for green. What was intended as encouragement quietly becomes permission. Before long, people aren’t asking, “How do we get back to standard?” They’re asking, “Isn’t yellow good enough?”

The more I reflected on that conversation, the more I realized yellow has an identity problem. Ask 10 people what yellow means, and depending on context, you’ll likely hear many different answers. Here are a few:
• Lines on the floor to note the standard location for a forklift or a safe lane for walking
• Amber andon lights to indicate that assistance is needed before a problem is escalated
• A yellow traffic signal meaning slow down and proceed with caution (unless you’re the driver who interprets it as a signal to accelerate before the light turns red)
• OSHA and ANSI standard color to highlight physical hazards
• Lean daily management boards to signal that a process is near to but not at standard

For this last example:
• Green is easy: on target
• Red is clear: not on target

To the question of target vs. actual, however, yellow is open to interpretation. Does it mean not quite red, or not quite green? Or maybe, almost? Yellow may simply mean “good enough for now.” The answer is no longer clear at a glance. In Billy Ray’s words, if we can learn to “celebrate the red” as an opportunity to problem-solve, then yellow isn’t needed.

What does yellow mean on your tier boards? More important, what action does it trigger?

Please comment below.

Published July 13, 2026, in the Old Lean Dude blog.

By the way: BTW: The LinkedXL Team will be joining us on Sept. 29–30 in Springfield, Massachusetts, at the upcoming Northeast Lean Conference. They’ll be hosting two complementary sessions, one on the fundamental LinkedXL approach to lean daily management and one to share the unique LinkedXL-OS operating system. Workshop attendees receive a six-week trial sandbox.