The Olympian reports that a 45-year-old dump truck driver was making a delivery from Montesano to Chehalis on Friday.
State patrol spokesman Guy Gill says the man was pulling a flatbed trailer with an excavator on U.S. Highway 101 when the excavator's boom crashed into the first overpass. The man continued driving southbound on Interstate 5 and the boom hit several other bridges.
State troopers finally stopped the truck before it could cause any more damage.
Gill said the driver told authorities he didn't realized he had hit anything.
Trooper Guy Gill said two cars travelling behind the truck had their tires flattened as they ran over debris knocked loose from one of the overpasses.
Transportation spokesman Doug Adamson says it's unclear how much the repairs will cost.
The truck driver is facing several potential violations and fines.