A Giles County pedestrian bridge that collapsed in October, injuring nine people, had a defective anchor bolt that snapped, according to a report released Thursday by the Virginia Department of Transportation.

The galvanized steel bolt was one of four that connected the two cables that ran along the top of the suspension bridge to heavy concrete blocks buried on both sides of Walker Creek.

Ten people were on the bridge when the bolt broke, causing one side of the bridge to fall and dump them in the creek the afternoon of Oct. 12. Five adults and four children were taken to Carilion Giles Memorial Hospital.

The 160-foot-long bridge hung about 30 feet over the creek and served as a secondary access for three households, VDOT spokeswoman Heidi Underwood said. It was used mostly when flooding made a nearby low-water bridge inaccessible to traffic.

Underwood said there are no plans or funding to rebuild the bridge.

After the incident, VDOT assembled a team of engineers and scientists to determine its cause. Investigators found that three factors contributed to the collapse: a small defect in the material of one of the anchor bolts, the way in which the eye bolts were configured and the unusual pedestrian load at the time.

The defect in the broken bolt is believed to have been the cause of its sudden failure, according to the report.

Underwood said there was a void underneath the bolt's galvanized coating. It could have been created when the bolt was manufactured or could have been caused by corrosion, she said.

The bridge had been inspected in March 2007 and given a rating of 7 on a scale of 1 to 10, Underwood said.

The defect was inside the hook and would not have been visible before it broke, she said.

"Further testing that compared the strength of the bolt to the amount of load present at the time when the bolt failed indicates that the anchor bolt would have supported the load present at the time of its breaking if there had not been a defect in the metal," according to a news release from VDOT.

As part of the report, which was completed by VDOT and the Virginia Transportation Research Council, recommendations were made to make other suspension bridges safer.

The Walker Creek bridge was one of 11 pedestrian bridges in Virginia secured with open-hook anchor bolts. While the bolts are adequate, the report says, closed-eye anchor bolts are safer. The report showed that strain had caused some of the hooks to weaken.

"There are similar bridges, but nothing that is exactly like this one," Underwood said. "What we are doing is inspecting these, evaluating them and then, if something needs to be done, what is it."