The A1 northbound was shut near Stamford this afternoon after a car with a caravan attached overturned.
A man and a child are said to have sustained minor injuries after the single vehicle incident.
One lane was open but has been closed to allow recovery.
There is congestion past Sibson near Peterborough and delays of 45 minutes are reported, although the road has now reopened.
Cambridgeshire police were called at 10.40am today (Friday, April 8) to the A1 just before the A43 junction.
The car is said to be on its side but the caravan is still upright.