Wanda Keating McGowan, who had been taking part in a fundraising walk for a breast cancer charity at the time, was hoisted over 22ft (6.7m) in the air.
Eyewitness Philip Glazebrook told the NBC6 television channel that the bridge made a loud alarm before opening and it was unclear why the woman had continued to cross.
He explained: ‘So she’s stuck on the bridge and she’s going up. The next thing is, she’s stuck, straddled like Jesus Christ.’
Witnesses said that the 55-year-old had to wait for over 20 minutes before being rescued by firefighters with a 24ft (7.3m) ladder from the bridge above New river in Fort Lauderdale, Florida, in the US.
In clear relief following the incident Ms McGowan posted a message on her Facebook page thanking the rescue team’s efforts: ‘To all the firemen and police officers. THANK YOU. YOU SAVED MY LIFE. ALL GOOD THINGS TO YOU.’