A woman who was on the wrong side of the barrier on Penwortham flyover on Tuesday was taken to hospital for treatment.
The A59 was closed while police helped the woman, who was in her 20s, at around 7.40pm.
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A spokesman for Lancashire Police said: “We were called at around 7.40pm on Tuesday (April 16th) to reports of concern for safety.
“Officers attended and found a woman, aged in her 20s, on the wrong side of the flyover bridge in Penwortham.
“Road closures were put in place, at Penwortham Brow, Middleforth roundabout and Kingsway.
“A short time later the woman, having been spoken to by officers, returned to the right side of the bridge.
“She was detained and taken to hospital for treatment.”