New York State Police report that a tractor trailer accident between exits 17 & 18 on Interstate 88 early Thursday morning is under investigation. Troopers report that the big rig was East bound when it went off into the medium and stayed upright. It happened around 7 a.m.  No one was hurt and the truck was later towed. State Police are looking at driver fatigue. The investigation is continuing as the New York State Police Commercial Unit checks out the truck.