BUCKSPORT – The Waldo-Hancock Bridge still has the structural strength of a new bridge built today, according to a recent engineering study.

But it is deteriorating, and, on Thursday, engineers from the Maine Department of Transportation explained that the deterioration in the main cables discovered last fall has shortened the useful life of the bridge.

Based on the current rate of deterioration and breakage of wires in the main cables, an independent engineering study said, it will take six to 10 years before the cable safety factor reaches a point that the state deems unsafe. At that point, the bridge would have to be posted or closed.

The engineers’ assessment does not take into consideration repairs now being made on the bridge, said DOT project manager Devin Anderson. Those repairs may slow the rate of deterioration, he said.

That information, which the department received from a private engineering company this week, has forced officials to consider new options for the 71-year-old bridge.

“New information requires new options,” said Bruce Van Note, the acting deputy transportation commissioner.

The department already has begun the planning process under the National Environmental Policy Act, which is required for any project seeking federal funding, and has contacted the state’s congressional delegation regarding funding for alternatives to the bridge.

Options vary from a short-term repair to construction of a new suspension bridge with construction costs ranging from $9 million to almost $39 million. Those figures do not include engineering costs or the cost to remove the existing bridge if that is necessary.

To help monitor the rate of deterioration in the cables, the department will install acoustic monitoring sensors on the bridge, which will track the number of individual wires that break within the main cables.

“That will tell us the safety factor and the rate of deterioration,” Anderson said. “We can determine if it’s a constant rate or if we’ve slowed the rate doing some of the work we’ve done.”

The presentation eased some concerns residents have had over the safety of the bridge.

“It’s eased my concerns somewhat,” said Paul Hansen of Verona. “What still concerns me is what they don’t know about the south cables.”

Most of the engineering study was conducted on the north cable, which has been completely unwrapped, sealed and re-covered. Some tests have been done on the south cable and a more extensive inspection and repairs are scheduled this spring.

While satisfied about the current safety of the bridge, some were still concerned that the rate of deterioration might accelerate as more wires break.

“The key is going to be the monitoring,” said Dave Milan, chairman of the local public advisory committee. “That’s going to help them determine the rate of deterioration.”

Denise Sheehan of Bucksport, one of the owners of Bend in the Road located on Route 1 near the Verona end of the bridge, said she was concerned about the possible location of a new bridge across the Penobscot River.

“We rely on tourists for our livelihood,” she said. “If the bridge is removed and the road doesn’t go by us anymore, that would have a financial impact on us. Of course, if it’s not safe, they’re not going to go that way either.”

DOT officials said several times that the NEPA process would decide the most feasible option for the bridge. The quickest and easiest option for a new bridge, Van Note said, would be to build it just south of the current bridge, keeping the main road in its current position.