Because of a bomb disposal in Mülheim an der Ruhr, a section of the A40 was completely closed on Thursday afternoon.
A city spokeswoman said there were no vehicles for 50 minutes between the Mülheim-Heißen and Mülheim-Winkhausen junctions.
The five hundredweight dud from the Second World War was quickly defused.
Mülheim - Then the journey could be released again.
Apartments in which around 130 people live had been evacuated within a 250-meter radius of the bomb.
dpa