Pictures from the scene showed a large concrete pumping truck toppled over with its long boom arm extended in front of it.
The truck was being used to pour concrete on the Tryon Road Greenway project.
It happened just before 7:30 a.m. While it wasn't immediately clear what caused the accident, the support arms of the truck appeared to have sunk into soft ground in front of it, possibly causing it to overbalance.
The truck belongs to Concrete & Material Placement out of Charlotte.
Officials said two workers were hurt. One man was knocked off a wall and a second had his torso pinched between two sections of metal. Both were taken to WakeMed with non-life-threatening injuries.