DOVER, Del. (AP) — Delaware’s transportation secretary ordered immediate inspections of major bridges in the state on Thursday to determine whether they might be at risk of problems similar to one that forced the closure of an interstate bypass in Wilmington.

DelDOT Secretary Shailen Bhatt also told The Associated Press that his agency is conducting an inventory of major bridges in Delaware to determine whether to determine whether the state’s property beneath the bridges is properly marked.

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The action comes after the Interstate 495 bridge was closed because of tilting support columns. The bridge, a bypass that helps alleviate congestion on I-95 and normally carries about 90,000 vehicles daily, has been closed since Monday, snarling traffic on the crucial north-south artery. It will be at least several weeks before it is reopened.

Officials suspect that the dumping of a large mound of dirt next to the bridge and on the transportation agency’s right-of-way shifted the ground underneath the bridge and caused the columns to tilt.

Bhatt said inspectors will start by looking at bridges of similar design in similar soils that might be at risk from the dumping of dirt or other material beneath them.

“I want eyes on all those bridges immediately,” he told the AP. “We’ve literally got folks going out today. This is something that folks will be working around the clock.”

After that, inspectors will look at every major bridge to see whether the state land beneath them is marked. The disappearance of a fence along the state’s right-of-way underneath the I-495 bridge has exposed a possible gap in the state’s inspection program, he said.

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“We need to get an inventory of all of our bridges and make sure right-of-way fencing is intact, and it needs to be part of our two-year inspections. If it isn’t, it needs to be. That will be part of our inspections as we move forward,” he said.

Bhatt said he doesn’t know what happened to the right-of-way fence that was once underneath the I-495 bridge.

“We’re going to determine when and who took it down,” he said.

Gov. Jack Markell planned to visit the site later Thursday.

The contractor who dumped the dirt next to the bridge is working with state officials to remove it. He was allowed to use the site under an arrangement with a company that leases land next to the bridge.

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“I have absolutely no idea what happened, I really don’t,” said James Thomas Jr., 60. “I’m not a structural engineer. I’m not a bridge engineer.”

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