Emergency crews responded to a report of a single vehicle crash on Mullowney Lane near the I-90 underpass. A Billings man operating a motorcycle was northbound on Mullowney Ln and hit the curbing around a concrete median. The collision with the curbing in combination with the high rate of speed caused the motorcycle to flip end over end for several feet. The driver of the motorcycle was not wearing a helmet and was found unconscious and not breathing. Witnesses on scene attempted CPR efforts while calling 911. American Medical Response and Fire Rescue crews arrived and took over CPR but were unable to resuscitate the driver who was eventually pronounced dead at the scene. Speed and alcohol have been determined to be factors in the crash. The name of the man will not be released until family can be notified.