A serious crash involving two tractor trailers on the northbound side of Route I-495 caused massive delays Wednesday.
The crash occurred about a mile before the exit for Route 111. One tractor trailer is on the left side and the other on the right side of the road as crews try to clear the crash.
Traffic was backed up by about four or five miles, all the way back to Route 62, shortly around 7 a.m.
One of the tractor trailers was hanging off the overpass. Stow Road, the roadway right underneath 495, is shut down because of a tire hanging over the side.
All lanes had reopened as of 11:25 a.m.