North Dakota DOT has not done specific research concerning vehicle warning light effectiveness.
Strobe and LED lights are allowed on NDDOT vehicles and equipment. LED lighting is preferred and used more popularly. Whelen Engineering is the deparment’s only approved manufacturer.
All NDDOT vehicles and equipment used for maintenance, construction, and surveying operations are required to use lights. Motor pool type vehicles (light-duty vehicles for official travel) are not authorized to have warning lights installed.
The only problems the department has experienced is with the effectiveness of an LED light compared to a strobe light. LED lights appear to be much more effective and draw much less power than strobe lights. Strobe lights have caused electrical interference with radios and other on-board computers, however the department has eliminated these issues with the new LED packages from Whelen Engineering.
The department does not track the age and effectiveness of lights on state-owned vehicles. Instead, the department uses the common sense approach: when a light loses its effectiveness, it is either replaced in whole or in part, depending on complexity of the system.
The department does require warning lights for private contractor vehicles in work zones.
LED warning lights may be the sole warning light on a vehicle as long as it has 360 degree coverage.
Vehicle warning lights must meet NDDOT approval, unless they are emergency vehicles, which must comply with federal regulations.
Plow trucks use 4-5 amber lights and 2 clear/white LED warning lights from Whelen Engineering. There are 2 cab-mounted amber LED lights providing 360 degree coverage, PLUS 2 rear LED amber lights and 2 rear LED clear lights. If the truck has a snow wing attached, the snow wing shall have an additional wing-mounted LED amber light installed.
State/Agency: North Dakota
Topics: Warning Lights