An 87-year-old driver overturned his car on the Autobahn 7 near Hamburg on Sunday and died.
It cannot be ruled out that a medical emergency was the cause of the accident, said a police spokesman.
The car only skidded in the construction site area, then hit the guardrail and finally overturned.
Hamburg - The A7 had to be closed between the Bahrenfeld and Volkspark junctions in the north direction.
Massive traffic obstructions must be expected, it said.
Just an hour after the accident, the traffic jammed for seven to eight kilometers, despite a diversion at the Bahrenfeld junction, said the police spokesman.
dpa