The Westfields area is on the western side of Fairfax, near the Loudoun County line.
Danny Betts, of 7553 Quail Run Lane, was headed north on Sully Road in a 1996 Saturn four-door sedan.
A tractor trailer, driven by Carl Wright, 44, of 221 S. 29th St. in Purcellville, was stopped at a red light.
Betts, who was behind Wright, slammed into the back of the trailer after trying to stop as the tractor trailer slowly accelerated upon the light turning green. Betts was not wearing a seat belt and was pronounced dead at the scene.
Alcohol and speed were not factors in the accident, police said.