VERONA – Extensive corrosion in the main cables on the Waldo-Hancock Bridge could force the state Department of Transportation to replace the 71-year-old structure instead of continuing the current $25 million rehabilitation project. Replacement cost for the bridge was estimated at $60 million.

“That’s a worst-case scenario,” Norman Baker, an assistant program manager with DOT, said Thursday at a meeting with members of the local public advisory committee.

But it is an option the department may have to consider.

The bridge is safe, Baker said. Preliminary results from tests on the bridge cables showed that the bridge has a factor of safety of 2.4, equivalent to the safety factor of new bridges being built today.

“It falls within the parameters of what we’re designing now, even with the deterioration of the cables,” said Devin Anderson, the project manager for the bridge project. “We have a safe bridge there.”

But the cables are deteriorating and, at this point, the department does not know how fast that deterioration is taking place. More detailed studies due to be completed in January will provide a better idea of how serious the problem is and how long the bridge will remain safe.

The need for those studies has forced the department to postpone replacement of the bridge deck, which had been scheduled to begin next fall. That project now will be rescheduled for the following fall.

The department has required spacing of 500 feet between commercial vehicles since discovering the corrosion problem, and Baker said he did not know how long that restriction would last.

The extent of the corrosion was discovered during inspection of the main cable on the north side of the bridge, part of the current rehabilitation project. The cable consists of 37 steel ropes arranged in a hexagonal spiral. Each rope is made of 37 wires. The main cables hold the suspender cables, which support the deck of the bridge. Those suspender cables also have been inspected and replaced as part of the rehab project.

Earlier spot inspections of sections of the cables indicated the presence of some corrosion. Concern about that corrosion was one of the factors in beginning the bridge rehabilitation project, Baker said. It wasn’t until the recent, more detailed examinations that the department learned the extent of the problem.

Using special equipment, contractors have been able to separate the individual sections of steel rope in the cable and to inspect each section. According to Baker, that inspection earlier this fall showed more corrosion than expected in the outer two layers of the main cable and some breaks in the individual wires. An estimated 80 to 90 of the 1,369 individual wires in the cable have breaks, Baker said.

Such breaks are not unusual in a bridge of this age, he said.

Inner sections of the cable appear to be in very good condition, he said.

That discovery, however, concerned the DOT engineers enough that they brought in a consultant to examine and conduct additional tests. The preliminary results showed that the bridge is still safe.

The results of more detailed study are due in January, and should provide more information about the extent of the problem. A second consultant will review those results, Anderson said.

In response to questions, the DOT officials noted that all the testing so far has been done on the cable on the north side of the bridge. Those studies have been extensive, but little has been done on the south-side cable.

“Don’t you need to do that to determine if that side is worse?” asked Waldo County Commissioner John Hyk.

Baker said an inspection of that cable is planned for next spring.

Officials took some heat from local residents concerned that not enough initial testing had been done on the bridge cables before the rehabilitation project began and that the presence of corrosion should have spurred additional inspections.

“Shouldn’t that have caused a heightened concern?” one man asked.

An area of extensive corrosion was discovered just 10 feet from where the initial tests were conducted.

Anderson said the initial examination was done in areas where problems generally occur with this type of suspension bridge.

“We made an educated decision based on how these bridges typically act,” Baker said. “There was a concern when we saw evidence of corrosion. It’s not the concern we have today. But we were concerned enough to begin the rehabilitation project.”

The only way to know the extent of the corrosion, he said, was to do what the contractor has done – examine the entire length of the cable.

The rehabilitation project on the bridge was designed to get another 30 to 50 years of service from the bridge, Baker said.

“If we don’t feel that we can get another 30 years from that bridge, we may have to explore other options,” he said.

Those options could include adding more cable to reinforce the cables or replacing the existing cable with new ones.

Although replacing cables once required dismantling much of the bridge structure, the DOT officials said new construction methods have been designed so that the bridge can remain intact and open while the cable is being replaced.

But the cost would be high, and therein lies the department’s dilemma. If the cost of rehabilitating and repairing the bridge gets too high, it could become more cost-effective to replace it.

That concern was raised several times during the session on Thursday by residents, some of whom had advocated for a new bridge instead of the current rehabilitation project.

Some people voiced frustration that they now find themselves in the same situation they were in several years ago, not knowing whether it will be better and cheaper to fix the bridge or build a new one.

“This is the same discussion we had in 2000,” said Rep. Richard Rosen, who, with Sen. Ed Youngblood, attended the meeting.

Rosen said the department had opposed a legislative proposal earlier this year to build a new bridge. With a new legislative session scheduled to begin next year, Rosen suggested that it might be time for legislators and department officials to review the new information about the bridge and to determine whether the department’s position has changed.

Replacing the bridge brings with it several difficulties, not the least being that the bridge is registered as a historic landmark, which places strict requirements on preserving it. That was a factor in earlier discussions about replacing the bridge, and likely will be a factor in the future if the department determines the bridge has to be replaced, Baker said.

Even if a new bridge is built, Baker said, it is unlikely the existing bridge would be torn down. It is possible it could be maintained as a footbridge or bicycle bridge. If it did not have to support vehicular traffic, its life span could be extended indefinitely, he said.

Tearing down the bridge would cost an estimated $12 million. If the department had to remove all the lead-based paint on the bridge before dismantling it, it would cost an additional $6 million, Anderson said.

DOT officials expect to have additional information on the bridge cables by the end of January and will hold another meeting with the local advisory committee when the data are available.