The crash happened westbound between junctions one and three of the motorway at around 6.20pm this evening.
A spokesman for Lancashire Road Police said there had been no serious injuries.
He said: "We are at the scene of an RTC on the M55 W/B. Thankfully no serious injuries but debris & vehicles across the carriageway for a considerable distance. Lane 1 will be opened imminently to allow vehicles to pass but please bear with us whilst we clear the other lanes."
Initially traffic was brought to a standstill.
At around 9pm, Highways England said all lanes had reopened but that there were delays on approach.
They said: "All lanes have re-opened. Delays remain on approach, which should now begin to ease. Thank you for your patience today."