The accident happened Monday night around 11:30 on the Main Street Bridge near the exit at Washington Avenue.
Police say Michael Ross, 45, of North Little Rock died at the scene.
According to the accident report, the man's motorcycle was headed north when it hit the concrete retaining wall and threw him and the bike underneath the bridge.
When police arrived at the scene to answer a call about someone needing help, they were met by Roger Rayfus, 56, who told officers the motorcycle hit him as he slept under the bridge. Rayfus also pointed to Ross' body lying on the sidewalk near the bridge.
Rayfus was taken to UAMS for his injuries, which police say did not appear to be life-threatening.