Lt Dave Parker said it happened around 9:20 p.m. at mile 112, near McHugh Creek.
Police said Powers was thrown from a blue 2004 Yamaha sport-bike onto Alaska Railroad property and was wearing a blue helmet and blue riding gear. A train was stopped as police conducted its investigation.
Witnesses told police that Powers was riding northbound and crossed into the southbound lane around a corner. Police said a southbound vehicle moved to the far right to avoid striking Powers and the motorcycle struck the guardrail and ejected Powers from the bike.
Powers went down the embankment landing near the railroad.
Police said a nurse traveling on the highway began CPR until medics arrived. Powers was pronunced dead on the scene around 9:40 p.m.
His motorcyle careened off of the rail and continued northbound for about 1000 feet without Powers and entered a ditch, struck a boulder, and came to rest in the roadway.
Traffic in the area was blocked because of the investigation for several hours and re-opened around midnight and police said high speed may have been a factor in the crash.
Anyone who may have seen Powers riding before the crash or who may have seen the crash are asked to call APD traffic investigator Rick Steiding at 786-2669.
KTUU's Neil Torquiano contributed to the Aug. 8 update when Anchorage Police released the identity and its intial report on the crash.