Relatives of a policeman killed in Mendi several weeks ago have blocked off the Highlands Highway outside of Goroka, preventing the free flow of traffic.
Constable Harry Gorano was injured during an ambush in Mendi.
He was in a coma for three weeks and died in intensive care.
Relatives are demanding the arrest of the killers.
The ambush occurred in January.
His colleagues were escorting a casket to Hela Province.
His collegue, Constable Noah Biape was killed during the attack.