When chilling winds blow and the temperatures drop, Metro Transit riders appreciate the warmth put out by overhead heat lamps on light-rail platforms and in bus shelters.

But in many cases, the mechanisms have not been working. Hundreds of the heat-producing units have been vandalized, and that's left riders like Kim Johnson, of St. Paul, shivering in the cold.

"It's not like a weenie roast with that heat, but it really makes a huge difference," said Johnson, a daily Green Line rider. "When we have those brutal days, it's uncomfortable. They take the edge off."

So Metro Transit this fall began installing stainless steel covers over the warmers to prevent criminals from smashing the 12-inch glass tubes that put out heat.

The grates were designed by Metro Transit electrician Jim Davis, who sought a solution to the persistent problem of fixing a unit only to have to return within days or weeks to make the same repair.

"We hope this can help us out," said spokesman Howie Padilla. "We know riders are out there and it's getting cold."

So far the agency has installed about 100 of the protective guards at bus stops along Marquette and 2nd avenues in downtown Minneapolis, and at some light-rail platforms.

If they prove successful, the heat lamp covers could be installed on more of the agency's 1,500 heaters, Padilla said.

Over the past couple winters, Metro Transit has spent tens of thousands of dollars to repair broken heat lamps. Electricians fixed more than 1,200 of the units last year alone, some of them multiple times, Padilla said.

Heat lamps are regulated to work when the temperature drops to 40 degrees or below. Riders push a button to turn them on; when they don't work, the agency hears about it through phone calls and social media posts.

"Platforms and bus stops are the front porch to our system," Padilla said. "It's our job to make for as good an experience as possible."

Padilla is unsure why people would vandalize the warmers. Johnson, who on Wednesday was thrilled to have heat back at the Hamline Avenue Station after it had been out for two weeks, was nonplused too.

"That breaks my heart," she said. "There are so many things to be mad about, but this is not where they should direct their anger. It makes no sense."

Catching the vandals has not been easy. But in a handful of cases last year, Metro Transit police identified the perpetrators and charged them with damage to property, Padilla said.

"We can pull video and try to identify people," Padilla said. "We try to hold people responsible."

Tim Harlow • 612-673-7768