Have you ever wondered why most emergency vehicle lighting in the U.S. is red and blue? Or, even more intriguingly, why not all police vehicles in the U.S. use the same color lights? We did a little digging to find out the reasoning behind these colors, learn why there are differences between agencies, and imagine what the future may hold for color in police vehicle lighting.
A Brief History of Emergency Vehicle Lighting
Looking at the evolution of police vehicles in the U.S., we found that when police departments first adopted automobiles to patrol their precincts in the early 1900s, they had no way of distinguishing them from civilian vehicles. Their first solution was to use convertible cars and keep the top down so that civilians would see their police hats–come rain, snow or sleet! Seeing the obvious flaws in this approach, PDs began experimenting with different paint markings, eventually landing on an all black car with white doors and roofs, often called “black and whites,” which are still seen in some precincts today.
It wasn’t until the 1930s that red lights were added to the roofs and grills of patrol cars to signal civilian drivers to pull over for a chat and possible citation. The lights were red because they were made from repurposed tail lights, and probably because red lights on the road meant “stop.” The trend caught on and evolved from there into the rotating “gumball” light of the late 40s, followed in the 60s by rudimentary versions of today’s horizontal lightbars.
The Introduction and Use of Blue Lights
According to retired police officer and criminal justice professor, Tim Dees, blue was added in the late 60s, when public safety officials noticed that Europe and other countries used blue for public safety–not red–likely to avoid confusion for sea and air traffic. Both nautical and aeronautical vessels have always used red to show other vessels the direction in which they are traveling (i.e., red lights are placed on the left-port-side of the vessel, and green on the right–starboard–side). This method is used internationally to this day.
Other sources point to color blindness as the reason for adding blue lights. What we call “color blindness” very rarely manifests as a complete inability to see color. Instead, most people with the condition have partial color blindness, which typically takes one of two forms; a difficulty in distinguishing between red and green, or difficulty in distinguishing between blue and yellow. The theory is that EVs were outfitted with both blue and red lights so that most color blind people will at least distinguish one or the other.
Whatever the reason, blue has become a standard color in emergency vehicle lighting, and it’s effectiveness over red, during the day versus at night, has been heavily researched in recent decades. A 2009 report by the U.S. Federal Emergency Management Agency (FEMA) summarizes several recent studies suggesting that blue lights are more visible at night than red. One of those studies, published by the Florida Highway Patrol (FHP) in 2004, found that red LEDs are more visible during the day than blue LEDs. FHP concluded that blue lights were better at night time because they give drivers a more accurate perception of the emergency vehicle’s motion than red, partly due to its stark contrast against a sea of red tail lights, but also due to the way the human eye perceives color at night versus during the day–more on that in our next article.
Other Colors in Emergency Vehicle Lighting
Three more colors were added to the mix of EV lighting after blue, each serving a different purpose. White is used on all sorts of emergency vehicles, but mostly only as a contrasting color, and for lighting up the scene of an incident. Amber (yellow-orange-ish) is used by authoritative and emergency vehicles as a way to caution surrounding drivers, usually in construction, towing, municipal, and other vehicles that may be moving slowly, and increasingly on patrol cars as a contrasting color. Green is often used in fire and emergency management, and in some states for volunteer firefighters, personal vehicles of emergency personnel, and for private and homeland security.
In the United States, state and local governments determine which warning light colors should be used for which purpose, causing some discrepancy between precincts. Here in Michigan, for example, most police departments use red and blue with contrasts of white and amber, but the nearby city of Hamilton just made the switch to all blue, emulating our neighbors to the south in the Ohio Highway Patrol, and other departments around the U.S. The Hamilton Police Department says that the switch aims for better visibility and safety, citing the aforementioned studies finding blue lights to be more visible at night. The majority of precincts still use blue as a contrasting color, saving all blue for personally owned vehicles (POVs) of EMS personnel, and sometimes for utility vehicles.
The Future of Emergency Vehicle Lighting
The FEMA study cites that about 25% of firefighter deaths happen on the road, and numbers are similar for police, emergency services, and other highway workers. Despite current inter-department inconsistencies, there has been a large national push for federal, state and local agencies to work together to implement solutions for decreasing these incidents. Because sirens often go unheard by civilians listening to loud music, using headphones or driving soundproof vehicles, FEMA says that emergency vehicle lighting is probably the most effective signal to other vehicles to pay attention and adjust course accordingly. With recent research suggesting that blue lights are more visible at night, maybe we’ll see more blue lights on police vehicles. Perhaps we’ll see more consistency between departments. Only time will tell.