The M55 was closed in both directions this afternoon, as police responded to an emergency incident.
Hundreds of drivers were stuck on both carriageways between junction three and junction four, and many more were forced to find alternative routes.
Police cordoned off the stretch of motorway after growing concerned about the welfare of a teenage girl on a bridge over the eastbound carriageway.
The girl is thought to have fallen from the bridge onto the motorway below.
An air ambulance was called, and North West Ambulance Service confirmed that the girl was taken to hospital with leg injuries.
The M55 has since reopened in both directions.
A spokesman for Lancashire police said: "An officer on patrol was flagged down at around 2.20pm today (Wednesday, August 28th) to reports of a concern for safety.
"We attended and found a girl on a bridge over the eastbound carriageway of the M55 close to junction four.
"Sadly the girl, aged in her teens, ended up on the carriageway.
"She was taken to hospital for treatment. Her injuries are not thought to be life-threatening.
"The M55 motorway was closed in both directions between junctions three and four while we attended but has since reopened.