BOISE – On average, two emergency workers are killed each month by passing vehicles while working at the roadside, but new AAA research could help to reduce that number.

The AAA Foundation for Traffic Safety recently studied the effectiveness of cones and flares that were used in combination with two emergency vehicle lighting patterns, as well as the effectiveness of vehicle-mounted variable message signs (VMS), in protecting roadside workers.  Many of these life-saving countermeasures were successful in changing driver behavior.

“Every state has a ‘Slow Down, Move Over’ law.  Drivers who approach a stationary emergency vehicle are required to slow down below the speed limit, and if possible, move over at least one lane to give tow operators and other first responders more room to work,” says AAA Idaho public affairs director Matthew Conde.  “Safety equipment can serve as an important reminder to do so.”

Between 2011 and 2016, tow truck drivers were killed while operating on the roadway at an annual rate of nearly 43 deaths per 100,000 full-time equivalent workers – far greater than the rate for all other industries (about 3 per 100,000 workers).

From 2016 to 2020, six people in Idaho were killed while outside of a disabled vehicle, while 1,703 people were killed nationwide.


Flares and cones in combination with two different light patterns

For this experiment, AAA staged an incident at the roadside that consisted of a flatbed tow truck using a Daytime or Nighttime light pattern while parked in front of a silver sedan with flashing hazard lights.  The patterns were tested during the day and at night, and with the additional use of flares, cones, or both.  Key results included: 

Lane Occupancy

  • During the day, the presence of the tow truck displaying the Daytime light pattern prompted a 25% shift out of the adjacent travel lane. Both the Daytime and Nighttime light patterns resulted in a 40% shift at night.
  • When flares were added to the truck displaying the Daytime pattern at night, the traffic in the adjacent lane shifted more than it did with the truck alone. But cones produced only a very small reaction that was not statistically significant.
  • When paired with the Nighttime pattern at night, both flares and cones yielded a large shift out of the adjacent lane beyond what occurred with the truck alone.

Neither flares nor reflectors produced a significant change during the day.

“As drivers, we may be somewhat de-sensitized to the presence of cones and flares, particularly during daylight hours when we have increased visibility,” Conde said.  “But any time there’s a piece of safety equipment positioned on the road, we need to be extra vigilant for emergency workers.”

Speed and Lateral Position

  • During the day, both flares and cones were surprisingly associated with small increases in speeds, with a statistically significant increase for the cones.
  • When flares or cones were added to the Daytime light pattern at night, both were associated with increased speeds and decreases in lateral distance from the tow truck. However, when added to the Nighttime light pattern at night, both cones and flares resulted in significant reductions in speed in the adjacent lane.  Lateral distance also improved, but not to the level of statistical reliability.


In a survey of towing industry professionals, 15% of respondents had survived being struck by a passing vehicle, while 60% had experienced near misses.  The majority of workers reported using cones and flares in a variety of situations.  Respondents stated that making cone retrieval easier and reducing the expense of flares would further motivate their use.

Here is video of AAA Oregon/Idaho’s Dan Gamble working on the roadside in close proximity to passing traffic.


Vehicle-mounted variable message signs (VMS)

AAA evaluated the effectiveness of VMS displaying a flashing diamond pattern.  When the system was active, the odds of a vehicle moving over were an astonishing 95% higher than without the message sign.  If a vehicle in the adjacent lane made a lane change when the VMS was active, its speed also tended to be slower.


Next steps

AAA’s research shows that safety countermeasures can be used in combination to better protect workers at the roadside, but that increased awareness of the state’s “Slow Down, Move Over” law is critical to changing driver behavior.  AAA urges service vehicle fleets to invest in these technologies wherever possible and will continue to partner with other traffic safety organizations to spread the word.

“When drivers actively scan the road for emergency vehicles and roadside workers, then slow down and move over as the law requires, everybody wins,” Conde said.  “Allowing workers to quickly clear the scene reduces traffic congestion and the possibility of secondary crashes, and even more importantly, our roadside heroes make it home safely to their loved ones.”