Less Than A Minute

 

As explained in the Milwaukee Journal Sentinel's article:

"The purple streetlights are back in the Milwaukee area, or may have never left after appearing on highways the last few years.

The Wisconsin Department of Transportation originally predicted in 2023 that fewer than 100 were left in the state and they'd soon be replaced, but an agency spokesperson said Thursday that "additional failures occurred in summer of 2023, which was more than anticipated."

The DOT installed a batch of LED lights in 2018, mostly in the southeast region. At least 300 lights began changing color from white to purple. The effect would lead to interstates being lit purple at night where these lights were highly concentrated."