CHICAGO (CBS) — Street light and traffic poles in Chicago are corroding to the point of snapping and toppling over on property and people.

On Thursday, a woman was struck by one outside the Thompson Center downtown.

The reason for this fall? Look no further than its base and all its rust. The decay had been hidden by a decorative cover.

Sources for the city who repair these poles tell CBS 2 the covers might have looked pretty at first, but their design has created a serious danger.

They trap water and the decorative shell makes it difficult for inspectors to see just how bad the poles might be corroding on the inside.

Dr. Sammy Tin, an IIT professor and materials engineer, said these decorative covers trap moisture from rain and snow.

“It’s a way of just basically covering up the ugliness of the rusted base,” Tin said.

Tin has worked with CBS 2 investigators since 2015 to expose decaying light poles. Back then, he said if the structure isn’t properly maintained, it’s subject to accelerant and corrosion due to the moisture accumulated in the box.

Others have had personal experience with the effects of the corrosion. India Cooley’s car was hit by a light pole in 2017.

“It’s going to take one death for them to do something about it, but they have the opportunity to do something about it now,” she had said.

Lauren Lammy’s car was struck by a pole in 2016. Luckily, she wasn’t in the car at the time.

“If that happened in the middle of rush hour, who knows what would have happened to someone else,” Lammy said.

There’s another design problem to blame — poles placed on hollow metal boxes which also trap rain, snow and salt.

CBS 2 reported bad poles outside of numerous schools and found one in 2015 on the same street eight years after one fell on 13-year-old Noni Brown, breaking her neck.

“See what’s going on? Oh my goodness, it’s all rotted out like the one that hit my daughter,” her mother said.

In all the reported cases, repairs didn’t happen until CBS 2 called the city.

“This is definitely a recurring issue. We’ve seen many, many light poles over the past number of years that I have been talking to you guys and we have pointed these issues out continuously without much of a solution,” Tin said.

The Chicago Department of Transportation says it’s in the process of identifying what caused the condition of yesterday’s pole and other light poles nearby to decay.

CDOT also said it inspects under the covers for corrosion.

But as Tin said, the design itself accelerates rust and corrosion.