By James Hughes
About 4-5% of the population experiences some level of color blindness, ranging from confusion of colors to complete greyscale vision; for these drivers, color-specific cues add layers of complexity, according to a recent Institute for Traffic Engineers (ITE) publication. For example, red and green (the most commonly used colors for traffic design), are also the colors most confused by color blind drivers. Differing shapes and patterns, in addition to color, can provide better road information to color blind individuals.
To combat confusion of drivers and maintain a uniform presence, general accessibility principles should be integrated into road design processes. These principles include:
- Not relying fully on color to communicate
- Utilize simulation when possible to identify contrast issues
- Have color blind individuals review color guidance
To upgrade current infrastructure or design into upcoming projects, accommodations can be made to benefit drivers with or without color blindness. Designing road signs to not blend into the surrounding environment and adding flashing lights or additional reflective striping are some of the easiest fixes. Lane striping patterns can also be adjusted to communicate pass/no pass zones or lane separation with striping patterns commonly used in Europe, which do not rely on yellow or white color paint.
For traffic signals, vertically mounted red signals can be mounted to form a “T” rather than a singular red signal. For horizontally mounted signals, a double red signal on the outermost positions can uniquely signal to stop.
The MUTCD provides standards and guidance on signage colors and gives flexibility on additional cues for aiding drivers in understanding current traffic signaling and permitted uses. These opportunities for improvement should be taken into serious consideration when designing a project to reduce the chances of fatal crashes with other drivers or pedestrians, as these improvements make information clearer for all drivers, and especially for color blind road users.
Photo credit: Clay Junell at Flickr