The northbound train was traveling 45-50 mph when it hit the westbound car, pushing it 120 feet before coming to a stop.
Utah Transit Authority spokesman Gerry Carpenter said 50 to 60 passengers were on the train at the time of the accident. No injuries were reported to UTA or crew members.
The accident closed TRAX travel through the crossing. By early afternoon, TRAX travel in both directions had resumed.
Keller said investigators had determined the crossing arms had been down for 22 seconds before the collision, and witnesses had reported that all facets of the system the arms, the bells and flashing lights had operated as designed.
Jeremy Hatt saw the car "fly down" 2950 South from his vantage point at the store where he works, about half a block east of the crossing. He estimated the car was traveling about 40 mph. Moments later, he heard the impact.
"Everyone screams down [this road]," Hatt said.
South Salt Lake firefighters had to use the "Jaws of Life" gear to extricate the victim from the wreckage. He was then taken by ambulance to the hospital where he was pronounced dead Wednesday afternoon.
Carpenter said this was the first TRAX fatality of 2013. Last year, five people were killed by TRAX trains, but three were suicides, Carpenter said.