It depends on the message, but digital highway signs could be more distracting than helpful

TAMPA, Fla. — From crash alerts to weather warnings and other safety messages, digital highway signs dot highways across the state.

Some states have even resorted to using humor and pop culture references to get drivers’ attention.

They’re intended to improve safety but could the messages be missing the mark?

Gabriel B. in Seminole asked VERIFY if these digital signs have the opposite effect and cause more crashes.

THE QUESTION

Do digital highway signs cause more crashes?

THE SOURCES

• Federal Highway Administration (FHWA)
• Florida Department of Transportation (FDOT)
• Josh Madsen, researcher at University of Minnesota 

THE ANSWER

Yes, in situations where certain messages are displayed, digital highway signs have been found to cause more crashes. Federal regulators have tried to reign in sign usage.

WHAT WE FOUND

State transportation departments have been using digital highway signs for decades to alert drivers of weather or road hazards and advocate for safer driving.

But despite the proliferation of these signs, there is limited research on their effectiveness and what does exist suggests they could actually increase crash rates.

Joshua Madsen, a professor at the University of Minnesota, co-authored a study recently published by the American Association for the Advancement of Science that found crashes actually increased in areas where digital highway signs displayed traffic death statistics.

Because Texas DOT consistently displayed traffic fatality rates once a week each month, Madsen said between 2010 and 2017 they were able to compare crashes that occurred in weeks when fatality stats were displayed with those that happened during the rest of the month and determine how the different signs impacted roads.

“I was shocked at the magnitude, the number keeps resetting and you just see the cyclical pattern of it growing throughout the year as the number of deaths displayed increases,” Madsen told VERIFY.

Madsen says the data suggests the message is so jarring it has the opposite effect by taking too much of the driver’s attention.

Florida’s Department of Transportation does not display traffic fatality statistics, instead opting for this list of approved messages.

“We have established a set of messages that are simple and brief while still maintaining legibility with minimal cognitive distraction from the driving task,” spokesperson Kris Carson told VERIFY. “The preference is to focus on positive messages that include a safety message.”

FDOT said it follows guidance provided by the Federal Highway Administration which says displaying statistics like highway fatalities is an “inappropriate” use of the signs.

The federal agency has also recently attempted to crack down on state DOTs resorting to use of humor or pop culture references in its signs. FHWA updated its Manual on Uniform Traffic Control Devices – essentially a big book of rules – in 2021 to lay out applications of an effective traffic control device.

The agency says, “use of witticisms, colloquialisms, and popular culture references that target or are comprehended only by a limited segment of the population is not consistent with a clear, simple meaning for all.”

Other studies on digital highway signs have found messages pertaining to speeding, fog or slippery roads are effective at reducing driving speeds.