BOSTON -- There are new safety concerns about the safety of the Ted Williams Tunnel because inspectors cannot reach thousands of epoxy bolts to ensure their strength.

NewsCenter 5's Gail Huff reported that the issue is slowing safety inspections inside the tunnel.

Inspectors are supposed to routinely check the ceiling bolts to make sure they're holding, but about 4,000 of the bolts cannot be seen because they're out of view.

Similar epoxy bolts slipped loose in July 2006, causing the ceiling collapse that killed a Jamaica Plain woman. Since that collapse, the 16,000 bolts inside the tunnel are supposed to be inspected regularly.

According to a story in Wednesday's Boston Herald, officials must now determine whether the tunnel needs to be retrofitted and how much that would cost.

There have already been numerous costly mistakes on the Big Dig project putting its price tag at nearly $15 billion.