The two coaches were carrying British schoolchildren on separate skiing trips to Austria.
The crash killed two people, one a 14-year-old boy and the other an assistant coach driver.
The cause of the accident is not yet known and is the subject of an investigation.
It is thought one of the buses had pulled up on the hard shoulder and was hit by a passing lorry.
There were 29 people injured in the crash, four were said to be seriously hurt.
The motorway was closed for hours after the accident as police cleared the wreckage.