AASHTO Journal, 22 December 2016
In an effort to reduce crashes on roadways, the Michigan Department of Transportation along with about 50 county road commissions and some municipalities said they will use green and amber lights on maintenance trucks this winter, lights that may be flashing, rotating or oscillating.
The reason? “Our visual system would be more attracted to a bright green light versus a bright white flashing light in a heavy snowstorm,” said Dr. Bernie Tekiele of the Michigan Eye Institute. “Our visual system is piqued to be sensitive to the green/yellow spectrum.”
Many state DOTs and local agencies each year report that cars and other vehicles crash into snowplows and other road-treatment trucks during winter storms, so the industry has been looking for ways to heighten the visibility of the maintenance vehicles even in snowstorm conditions.
The announcement said studies suggest that humans can differentiate between more shades of green than any other color, and “better visibility with green lights means safer roads for winter maintenance workers and motorists.”
New state legislation amended the Michigan Vehicle Code to allow for the use of the color green on maintenance vehicles.
The Kent County Road Commission has been piloting the use of green lights for the past two years and cites “great success.”
Jerry Byrne, KCRC deputy managing director, said: “We haven’t had any rear-end accidents with the green lights on the trucks that we’ve had for the past two years, and that’s what we’re really trying to eliminate … We’ve had injury incidents in the past, so our goal is to spend a little money to save the number of accidents.”
As fleets replace the older lights on their winter trucks, they are incorporating green lenses where other colors were used in the past. “The cost, really, to the state is just the lens on the back of a light. It’s small. Something less than $100 per truck,” said Mark Geib, MDOT engineer of the department’s Operations Field Services unit. “So, since we put lights on anyway, in time there’s really going to be no additional cost to speak of.”
An MDOT video about the changes is available here.