How Different Colored Warning Lights Prevent Rear-End Collisions Plow Trucks

Kanon Kulpa

We all do it. It’s snowing, and you’re behind a snowplow going 30 mph. You’re getting impatient, wanting to pass the truck as soon as possible.

However, the heavy snowfall and reduced visibility mess up your ability to accurately judge distance and speed.

And before you know it, you’re getting too close to the truck. You hit the brakes a little too hard—momentarily forgetting that the roads are slick—and you’re sliding quickly toward the truck’s rear-end.

How State DOTs are Finding That Different Colored Warning Lights Prevent Rear-End Collisions with Snowplow Trucks

Since 2012, various state DOTs have experimented using different types and colors of warning lights to alert motorists that they’re getting too close to the trucks.

These DOTs found LEDs work the best for warning lights—LEDs last longer, cost less and are the closest to actual daylight. And snowplow operators preferred amber and bright blue warning lights.

However, LEDs don’t heat up enough to keep snow and ice from forming on them. So, DOTs experimented with mounting these lights high off the back of trucks with airfoils as well as lower on the back of trucks to avoid snow accumulation.

The good news: studies proved over and over again that there’s a reduction in car accidents involving snowplow trucks when colored, flashing lights are employed.

Next, state DOTs needed to lobby their state legislatures to allow colored, flashing lights on snowplow trucks.

For example, in Iowa, IDOT performed a two-year study of using blue and white flashing lights on their snowplow trucks and found that the lights improved visibility and reduced accidents with motorists.

During a typical winter, there would be 29 car crashes involving snowplows. However, when trucks used flashing blue and white lights, there were only 10 car crashes involving snowplow trucks during that winter.

According to an article in Des Moines Register,

“The Iowa Legislature modified the law in 2015 to allow for a three-year research project with blue and white lights in central Iowa. But DOT officials say the evidence from just two years of data is so clear that the [sic] third year of study isn’t necessary. They plan to ask state lawmakers in January to consider permanently authorizing the blue and white LED lights statewide on snowplow trucks.”

Read how to keep up on maintenance and other chores between snowstorms.

Changing State Laws

Studies showed that there were fewer accidents between motorists and snowplow trucks as a result of different colored warning lights. However, state laws were on the books that only flashing lights were allowed to be on emergency vehicles.

But some states, like Ohio, use green and amber lights on their trucks. So the laws needed to be re-written to include flashing green lights on Ohio snowplow trucks.

ODOT created a fact sheet on their website, after changing their laws in 2012, to include flashing colored lights on the back of all snowplow trucks.

Here is a sampling of the changes involving the law:

  • “These changes are a result of House Bill 487 (Mid-biennium Budget Review) ORC 4513.18. The law went into effect on 9-10-2012.
  • The new law applies to headlights, clearance lights, identification lights, and other lights on snow removal equipment.
  • The new law permits the use of flashing colored lights, other than blue or red as those colors are reserved for law enforcement and emergency vehicles only.
  • Ohio will be one of the first states to use multiple colored lights and will be the first to use green.
  • Better visibility will lead to safer roadways as the motoring public can quickly and easily identify these vehicles in adverse weather conditions.”

Speaking of road safety, here is a blog focusing on your part to keeping the roadways safe.

The Takeaway from These DOT Studies

Your state may be changing their laws to include flashing, colored warning lights on their trucks. Many snowplow drivers in other states applaud the change because it means fewer accidents.

Plus, snowplow drivers can now focus on getting the job done—rather than worrying about motorists trying to pass by them on a blustery, snowy night.

In a Bridges and Roads’ article called, “Can You See Me Now?” the author shared best practices for snowplow truck warning lights:

  • Amber colored rear warning lights are the most popular. But there is no clear evidence that amber is the best color for warning lights.
  • State DOTs are experimenting with different colored lights—flashing and constant burn—to see the effect different colors have on reducing rear-end collisions with motorists.
  • It’s been shown that snowplow trucks need rear warnings lights consisting of constant burn lights lower on the truck and flashing colored lights above the truck to alert motorists.

You can read more on this popular trend of warning lights. Here are some news clips and articles from states where flashing, colored lights are used successfully on snowplow trucks:

The Center for Environmentally Sustainable Transportation in Cold Climates in Montana studied auxiliary and warning lights’ effectiveness.

Iowa: IDOT is experimenting with flashing blue and white lights.

Back in 2014, Kent County, Michigan’s road commissioner saw the success of flashing green lights on trucks in Ohio. By 2016, Michigan DOT started using green flashing lights and constant burn amber lights on the back of their trucks.

Check out ODOT’s success in changing their snowplow trucks’ warning lights to green and how they changed state law.

Is your state experimenting with different colored warning lights? What has been your experience?