It happened on the 3700 block of North 2nd Street on Friday morning.
That's where the victim, a man in his 60s, was struck around 11 am.
Police say the man was standing in the middle of the road when he was hit.
The driver of the 18-wheeler stayed at the scene.
There was no immediate word on if the driver would be charged.
The man who was struck has not been identified.