A tractor-trailer carrying huge culvert pipes lost its load Friday afternoon, shutting down Interstate 81 northbound and backing up traffic for hours.

The truck driver reported that a car cut him off near mile marker 127 about 12:40 p.m., causing him to slam on his brakes, Virginia State Police Sgt. Rob Carpentieri said. His load of three industrial pipes -- each weighing 5,000 pounds and measuring 40 feet long -- shifted and fell off the truck.

The pipes gouged the pavement, Virginia Department of Transportation spokeswoman Heidi Underwood said, forcing crews to shut down the northbound lanes while they repaired the asphalt and removed the pipes and the tractor-trailer.

About 100 feet of guardrail was destroyed, Carpentieri said.

Traffic was detoured off the interstate at Exit 118 in Montgomery County onto U.S. 460 east. Vehicles re-entered the interstate at mile marker 132 at Dixie Caverns.

The incident caused backups on several secondary roads, including Roanoke Street in Christiansburg, and led to at least two minor crashes.

One accident happened at I-81 mile marker 123 and another at mile marker 113, leading to the closing of the right lane in that area for a short time.

No one was hurt, Carpentieri said.

The driver of the truck, 58-year-old Edwin Adams of St. Cloud, Fla., was charged with failure to secure his load, Carpentieri said.

Both lanes of I-81 had reopened by 3 p.m., but backups of up to nine miles were still reported on the interstate for about another hour.

Underwood said crews would return to the interstate about 10 p.m. Friday, when traffic was less heavy, to finish repair work.