Speed and alcohol were factors in a motorcycle crash that killed a 31-year-old Honolulu man this morning on Moanalua Freeway, police said.

At about 1:45 a.m., the man was riding a motorcycle Ewa-bound when he lost control along a curve in the freeway before the Red Hill offramp, veered onto the shoulder lane, and struck a guardrail, police said. He was thrown from the motorcycle and died at the scene. He was not wearing a helmet.

Police said it was the 15th traffic fatality on Oahu this year compared to eight at this time last year.

The previous traffic fatality was also a motorcyclist who police said lost control and slammed into a guardrail. That crash happened late Friday night on the H-3 Freeway in Kaneohe, just past the Likelike offramp. Police said that motorcyclist, a 21-year-old Kaneohe man, was wearing a helmet, but was ejected and died at the scene.