The preliminary report, released Thursday by the National Transportation Safety Board, says trucker Kevin Roper was driving 65 mph at the time of the June 7 crash.
The report says that about a half-mile south of the crash on the northbound New Jersey Turnpike, signs advised drivers to slow from 55 mph to 45 mph because of construction ahead.
The truck plowed into Morgan's limo van. Morgan is hospitalized in fair condition with a broken leg and other injuries.
Roper, who is from Jonesboro, Georgia, was driving the truck for Walmart. Walmart says its trucks are equipped with devices that limit speed to 65 mph.
PEOPLE contacted Roper's lawyer for comment but the request was not immediately returned.