PLYMOUTH (CBS) — One man was killed when his car crashed Monday afternoon on Route 3 in Plymouth.

State police say Christopher E. Richert, 49, of New Bedford, was driving south on the road when his pickup went off the road into the center median, hit several trees, rolled over and landed on the driver’s side. They say Richert, who was the only person in the car, was not wearing a seatbelt.

Troopers are investigating excessive speed and possible mechanical problems as factors in the crash.

The southbound side of the highway was nearly closed, with only the breakdown lane open, for almost two-and-a-half-hours while troopers worked at the scene.