Answer Man

This is why blue lights are used on emergency vehicles

Q: Why are we seeing more emergency vehicles with blue lights? I always thought red was the universal color for emergency warnings. Why the change?

P.W., of Cahokia

A: As the Big Bad Wolf once famously told Goldilocks, “The better to see you, my dear.” Or, in this case, the better for you to see them.

That’s the reason Ohio law enforcement agencies, for example, have been giving the past few years in making the switch from the age-old red to the new, cool blue (which is almost universal across the pond in Great Britain). The Ohio Highway Patrol changed to all-blue light bars in 2012, and its move continues to be copied by smaller forces around the state — Fairfield in 2014 and Hamilton just last year.

The reason? They’re simply safer for all concerned, Hamilton Police Capt. Trent Chenoweth told the Hamilton-Middletown Journal-News at the time. He pointed to several studies that show blue lights are more visible and brighter both at night and during the day.

In 2004, the Florida Highway Patrol looked into how the eye perceives colors, particularly red and blue. It found that at night, your mind will perceive that a lamp emitting a higher frequency and shorter wavelength of light (e.g., blue or violet) will appear to be moving closer while a light with a lower frequency and longer wavelength (red) will appear to be moving away.

Chenoweth argues this is important because if you think the blue light is coming toward you, you may believe the vehicle is closer than it really is and react faster, adding to your margin of safety. If you think the red light is moving away, you may react more slowly, creating an additional hazard.

Then, in 2008, the University of Michigan Transportation Research Institute found that blue was more effective than white, yellow or red in sunlight conditions. It was a finding supported by studies from the Society of Automotive Engineers, U.S. Fire Administration and a 2012 study from Federal Signal, a company that manufactures emergency signaling and communications equipment.

Some say the blue lights are particularly effective at night.

“Think about it,” Fairfield Police Chief Mike Dickey told the Journal-News last year. “If you are driving down the road at night what do you see? Red (tail) lights. Blue lights are more visible and stand out. You know it’s a police officer.”

That’s why the West Chester, Ohio, Police Department ditched red way back in 2004.

“It was based off a 20-year study about the effect of emergency vehicle testing,” Officer Michelle Berling said. “It found if a person was color-deficient, red was the first color they could not detect. Blue is at the other end of the color spectrum.”

Some — including the physics department at the University of Illinois — argue that when it comes to safety and visibility the red-blue debate is a tossup. They say red may be more visible in the daytime because blue may be harder to pick out against the bright blue horizon of the sky. Some also argue red has an advantage in haze and fog. Perhaps, then, the best solution are the local police cars I noticed just the other night with a mix of flashing red and blue on their light bars.

Whether it be a fire engine, a police officer or an ambulance, if its lights and sirens are on, here are the basics for yielding to emergency vehicles.

Today’s trivia

Alexander Graham Bell may have invented the telephone, but who is usually credited for inventing the phone number?

Answer to Saturday’s trivia: At 1:01 a.m. on Oct. 2, 1955, Belleville experienced a revolution in phone service when it reportedly became the smallest city in the nation to adopt Direct Distance Dialing. Yes, your kids, who can dial Timbuktu with the phones in their back pockets, will think you’re joking, but until that moment callers needed a human operator to place any and all long-distance calls. At that time, an army of operators were standing by to make the connections at the Southwestern Bell headquarters on Market Square. But on that early Sunday morning, much of that laborious work was transferred to the new, automatic switching machines at the company’s new HQ at B and 1st streets. According to the Monday News-Democrat, all went smoothly except for things getting a little overloaded at first when everybody stayed up late to try the new-fangled convenience.

Roger Schlueter: 618-239-2465, @RogerAnswer