Why streetlights on Milwaukee interstates, highways are purple

Why some streetlights are purple in Green Bay, Oshkosh, Wausau

Overpass hi-res stock photography and images - Alamy

Why some streetlights are purple in Green Bay, Oshkosh, Wausau

Any locals know what's up with the blue LED freeway lights on the on/off ramps? : r/milwaukee

Wisconsin DOT says purple-colored street lights are a manufacturing defect

Curved road night hi-res stock photography and images - Page 7 - Alamy

Do you know why some Milwaukee highway and interstate lights are purple?

WisDOT: Manufacturer defect causes purple-blue lights on highway

Do you know why some Milwaukee highway and interstate lights are purple?

Purple street lights in Tallahassee: Defect leads to distracted drivers

How are lightbulbs on US interstates changed? - Quora

Curved road night hi-res stock photography and images - Page 7 - Alamy

Work to begin in March to remove more purple streetlights on Milwaukee highways