Updated at 7:15 p.m.

A 35-square-foot metal panel fell an estimated 130 feet from the Portland Aerial Tram, hitting a 21-year-old woman in the head as she walked down the stairway of a Southwest Portland pedestrian bridge Tuesday morning.

Portland Fire & Rescue responded to the incident at about 11:45 a.m. The woman had just walked across the Darlene Hooley Pedestrian Bridge, which spans Interstate 5 and connects the South Waterfront area to Lair Hill, when she was hit in the head by the falling metal.

Lt. Rich Chatman, spokesman for the fire bureau, said the woman suffered minor injuries and didn’t ask for further treatment. Firefighters say they were surprised her injuries, or the incident overall, wasn’t worse.

“This individual was very lucky to have sustained minor injuries,” Chatman said. The metal fell on the staircase of the bridge instead of plunging to the roadway and Interstate 5 nearby.

Dan Sprauer, the woman’s father, said she is a Portland State University student who lives in the Corbett neighborhood and was heading home to study for a 5 p.m. final exam when she was hit just above her right eye.

“It just came down on her, she literally didn’t see it coming,” Sprauer told The Oregonian/OregonLive. “She said it hit like a ton of bricks.”

He described the metal panel as appearing like the bumper of a car. Sprauer said his daughter was dazed by the impact, and a man walking behind her called 911. She waved off an ambulance because “she’s one of those people that doesn’t want to be a bother to others,” the father said.

Sprauer said he took her to a hospital around 1:30 p.m. for an evaluation. There is swelling on her head, but it appears she escaped serious injury, Sprauer said.

“It had some jagged edges on it, but thankfully none of them hit her,” Sprauer said. “It could have been far worse.”

He said his daughter wasn’t able to make her 5 p.m. exam and said they plan to speak to city representatives about the incident in the coming days. He said the tram passes over his daughter’s backyard.

The tram, which opened in 2006, is owned by the city. Some 10,000 people ride it between Oregon Health & Science University’s Marquam Hill and waterfront campuses every day.

It’s unclear how many people were onboard Tuesday.

Dylan Rivera, a Portland Bureau of Transportation spokesman, said the panel was a “decorative metal veneer” and not a structural element critical to the tram’s operations. He said it just gives the tram its aerodynamic shape.

“Nothing like this has ever happened before,” Rivera said, citing the tram’s more than decade-long history. The city planned additional inspections of the tram overnight to ensure the cabins were safe.

The tram was headed east toward the South Waterfront when the panel was dislodged, and the estimated 7-foot-by-5-foot “decorative panel” faced the Willamette River, Rivera said. It’s unclear what caused the piece to plunge the estimated 130 feet to the bridge below.

Chatman said fire crews asked the tram operator what happened, and they were told a strong wind gust upward of 20 mph occurred at the time of the incident.

Rivera confirmed the city would look at strong winds as a potential factor, but the tram is OK to operate, Rivera said, in winds of up to about 60 mph.

“We are still investigating the cause,” he said.

OHSU put out a brief message about the incident through its internal message board, according to a spokesman.

The tram was shut down for about 15 minutes as crews performed a thorough inspection, according to Rivera. Crews will give the tram cabins another thorough inspection Tuesday night, he said.

-- Andrew Theen

atheen@oregonian.com

503-294-4026

@andrewtheen