Parts of the M57 highway, parallel to the R21 in Centurion, were closed following violent protests on Thursday morning.
Gauteng police spokesperson Colonel Lungelo Dlamini said protesters blocked off a section of the road near the L and J informal settlement.
"A truck and a bus were set on fire. No one was injured in the process," he said.
Dlamini added that police were on the scene and that no arrests have been made.
He advised motorists to avoid the area and to use of alternative routes.