The project involves converting more than 28,500 roadway lights from traditional high-pressure sodium to LED or light emitting diode technology. The conversion includes replacing the light fixtures and bulbs.

“Drivers will see whiter light, but the biggest impacts will be a large reduction in the energy bill and eliminating the cost of bulb replacement every four years,” said Michael Gerbensky, signal design and lighting management engineer for MnDOT’s Twin Cities’ Metro area. “This means having our maintenance personnel out on the roadway less often, which reduces traffic control costs and it means improved safety. That savings can go to preserving our roadways.”

MnDOT expects that average annual savings in energy costs will be up to US $1.45 million with an additional US $500,000 savings per year in maintenance and replacement costs for the light fixtures and bulbs.

The new lights are being installed mainly on bridges and roadways, but other areas, such as weigh stations, rest areas, tunnels and maintenance facilities, are also being considered.

About 10,000 lights are in Greater Minnesota with the rest in the Twin Cities Metro area. Installations in the Twin Cities will be completed by the end of this year. In Greater Minnesota the conversion will take longer because of the large geographical area, but the whole conversion is anticipated to be complete by 2020, said Sue Zarling, traffic electrical systems engineer.

MnDOT expects the LED lights will last about 100,000 hours, or an average of 18 years.