Matt Helms

Detroit Free Press

They've popped up across downtown: Portable lighting towers on wheels that illuminate the streets at night.

The temporary lighting is how Detroit's Public Lighting Authority is keeping the light on downtown while crews tackle one of the last segments of the $185-million revamp of the city's streetlight system that fell into such disrepair that as many as 40% weren't working when Detroit filed for bankruptcy protection in 2013.

Lighting authority spokesman Bob Berg said the agency is spending $1,000 a month to rent each of the portable light poles — with about 130 stationed at various locales, although the number can vary — to help keep downtown safe and lit. He said the money was budgeted into the project.

“You don’t want any dark spots in downtown,” Berg said Wednesday.

It will take longer for the lighting authority to replace streetlights downtown because the grid of circuits that power the lights are underground, sometimes requiring crews to dig up sidewalks and streets. And in order to work on those lines, the power is shut off to them, leaving parts of downtown unlit.

Berg said it can take a month or more for crews to finish their work on some segments of the grid, and the portable lights are deployed as needed.

So far, about 60 streetlights have been replaced downtown and are up and working. Berg said the lighting authority will put up 2,300 streetlights, with about 700 on newer poles that can be reused.

It's not that the circuits serving the streetlights downtown are old and outdated. Most are about 15-20 years old. But Berg said crews have to replace the circuits so that they connect to DTE Energy power sources, and not the grid of the city's old Public Lighting Department, which the city opted to phase out, beginning in 2013.

In addition, the older circuits were 480 volts, but the newer LED lights Detroit has installed citywide require only 120 volts, Berg said.

“Once the new circuits are completed, then the new poles and lights are installed,” he said.

Berg said only downtown and a handful of historic areas in Midtown remain unfinished in the lighting project. He said the work is on schedule to be complete by year's end.

Contact Matt Helms: 313-222-1450 or mhelms@freepress.com. Follow him on Twitter: @matthelms.