Why Lime-Yellow Fire Trucks Are Safer Than Red
Red may be the traditional color of fire engines, but human factors and ergonomics research finds that lime-yellow fire vehicles are less likely to be involved in accidents.
Picture a fire truck and you are likely to see red — fire engine red. But when it comes to safety, human factors and ergonomics research paints a different picture. Much of what we know about human factors and ergonomics relies upon psychological studies of human visual and auditory perception. This research shows that because the color-transmitting cones in our eyes don't work well in the dark, some colors are easier for us to see at night. We are most sensitive to greenish-yellow colors under dim conditions, making lime shades easiest to see in low lighting. A 2009 study by the U.S. Fire Administration (USFA), a division of the Federal Emergency Management Agency (FEMA), also concluded that fluorescent colors, including yellow-green and orange, are easiest to spot in daylight.
Researchers (and volunteer firefighters) Stephen S. Solomon, OD, an optometrist, and James G. King were aware of these perceptual differences when they analyzed accident data from the Dallas Fire Department. In the 1970s and early 1980s, Dallas started replacing its red fire vehicles with lime-yellow fire vehicles with white upper cabs. After the early 1980s, the fire department bought red vehicles with white cabs. During their four-year study published in 1995, Solomon and King found that the risk of a visibility-related, multiple-vehicle accidents may be as much as three times greater for red or red/white fire trucks compared to lime-yellow/white trucks. The results also showed that when lime-yellow/white fire emergency vehicles were involved in an accident, the likelihood of injury or towaway damage was less than for red or red/white vehicles involved in an accident. An earlier study by Solomon involving nine cities and 750,000 fire vehicle trips found that lime-yellow fire trucks were half as likely as red trucks to be involved in intersection accidents.
However, later studies have qualified these findings. While the 2009 USFA study confirmed that fluorescent yellow-green and orange may increase vehicle visibility, the report also concluded that recognizing the vehicle was more important than paint color. Therefore, if people in a particular community don't associate the color lime with fire trucks, then yellow-green vehicles may not actually be as conspicuous as intended.
Furthermore, color is not the only important factor to consider when design vehicles to be conspicuous. Researchers have also found that retroreflective striping significantly increases a vehicle's nighttime visibility.
The National Fire Protection Association (NFPA) estimated that in 2011 there were 3,870 injuries sustained while fire department vehicles were responding to or returning from incidents. The U.S. Fire Administration reported that motor vehicle accidents were the cause of more than 10 percent of firefighter deaths in 2012. Additionally, such accidents can also injure or kill civilians.
While some communities have converted their fire fleets to fluorescent green, others have since gone back to the classic fire-engine red, in the interest of making the vehicles highly recognizable. In 2009, the U.S. National Fire Protection Association released a voluntary national standard for fire apparatus that requires retroflective striping in many locations on the vehicle. More work remains to be done to determine the most conspicuous features for emergency vehicles. As psychologists learn more about human perception, communities can continue to optimize their emergency fleets, resulting in fewer accidents and lives saved.
Federal Emergency Management Agency (2009). Emergency Vehicle Visibility and Conspicuity Study (FEMA Publication No. FA-323). Emmitsburg, Maryland.
Solomon, S.S., & King, J.G. (1995). Influence of color on fire vehicle accidents. Journal of Safety Research, 26, 41-48.
Solomon, S. S. (1990). Lime-yellow color as related to reduction of serious fire apparatus accidents: The case for visibility in emergency vehicle accident avoidance. Journal of the American Optometric Association, 61, 827-831.
American Psychological Association, February 2014