How Colorblind People See Traffic Lights

For the estimated 300 million people worldwide with color vision deficiency, traffic lights present one of the most safety-critical color discrimination tasks in daily life. The standard red-yellow-green color scheme was designed long before color blindness was well understood, and it uses the exact color combination that is most difficult for the most common types of color blindness. For someone with protanopia or deuteranopia, the red signal may appear dark brown or olive, while the green signal can appear yellowish — making red and green potentially indistinguishable by color alone.

The most important strategy colorblind drivers use is positional recognition. In virtually all countries, traffic lights follow a consistent layout: red on top, yellow in the middle, and green on the bottom (or left-to-right in horizontal signals). By memorizing the position of each signal, colorblind drivers can identify which light is active without needing to perceive its color. Brightness differences also help — red lights often appear dimmer, while green lights tend to have a noticeable blue tint that distinguishes them. Many colorblind people report that they adapted to this system so naturally that they were unaware of their deficiency until formally tested.

Some cities and countries have adopted colorblind-friendly modifications to traffic signals. Japan introduced blue-tinted green signals in the 1970s, making them easier to distinguish from red for people with red-green deficiency. Canada has experimented with adding shapes to traffic lights — a diamond-shaped red, circular yellow, and cross-shaped green — to provide shape-based identification alongside color. LED traffic lights have also improved things somewhat, as their purer, more saturated colors create slightly larger perceptual differences than older incandescent bulbs. However, universal adoption of colorblind-friendly signals remains inconsistent globally.

In most countries, color blindness alone does not disqualify someone from obtaining a driver's license. While some countries (such as Romania and Turkey) historically restricted or banned colorblind individuals from driving, most modern regulations recognize that positional cues make safe driving possible for colorblind people. In the United States, there is no federal color vision requirement for a standard driver's license, though commercial driver's license requirements vary by state. Studies have consistently shown that colorblind drivers do not have statistically higher accident rates at signalized intersections.

While standard three-phase traffic signals can be managed through position, certain signal types are more challenging. Flashing red or flashing yellow signals at intersections present a single light without positional context, making color identification the only cue. Temporary construction signals, railroad crossing signals, and single-light warnings can also be ambiguous. In these cases, colorblind drivers rely on brightness, context (presence of stop signs, railroad tracks), and cautious behavior. Some navigation apps now include audible or text-based traffic signal information as an accessibility feature.