A 59-year-old Chicago man died Wednesday, July 8, in a fatal motorcycle accident on Interstate 90 near Snoqualmie.

The accident happened about 6 p.m. west of exit 25. The cause of the collision is under investigation, but authorities believe the rider may have had a heat attack.

He was riding in the far left lane, when witnesses saw the cycle start to swerve, then drift off the roadway as the highway curved to the right, according to reports.

No other vehicles were involved, as the cycle drifted away from traffic due to the curving roadway.

The cycle traveled about 100 feet down the grassy median strip. The man’s body was found about 10 feet away.

“Every collision is different,” State Trooper Da Atchison said. “A motorcycle and rider can stay together for quite a while if a bike stays upright, just from centrifugal force.”

There are no indications that speed, aggressive driving or impairment played a factor in the crash.

The left lane of I-90 was closed for about half a mile as troopers and the county medical examiner responded. With light traffic, there were no backups, Atchison said.