AUGUSTA – The state had indications of potential problems with cables supporting the Waldo-Hancock Bridge as early as 1959, but the warning flags apparently were not red enough to prompt further investigation.

The state Department of Transportation acknowledged its problems with oversight of the bridge Wednesday when DOT leaders gave legislators a chronology outlining the bridge’s inspection and maintenance history.

The department said in its report that it believes department leaders “made reasonable decisions based on the available information and recommendations of the experts. With the benefit of 20-20 hindsight, obviously we wish we had engaged more detailed second opinions. However, in the end, we stand by our work and our decisions.”

The 2,040-foot-long suspension bridge spanning the Penobscot River at Prospect and Verona Island was opened to traffic in 1931. When DOT launched a $25 million renovation this year engineers discovered rusted and brittle cables on both sides of the bridge. The damage is beyond repair, and DOT has recommended that the bridge be replaced.

The bridge is one of 50 suspension bridges in the United States and was designed by renowned engineer and designer David B. Steinman.

Steinman died in 1960, but his New York-based consulting engineering firm, Steinman Boynton Gronquist & Birdsall, has performed a number of inspections of the structure. The firm is now part of the international engineering company Parsons and continues to perform work for DOT.

The first sign of rust on the cables was discovered during a Steinman inspection in July 1959.

Steinman said it appeared that water was penetrating the wrapped cables and that “this condition should be investigated and corrected as required,” according to the report.

Other than a 1961 widening project that reduced the size of the sidewalks and a new paint job in 1964, DOT never followed up on Steinman’s recommendation that a more detailed inspection be undertaken.

A second inspection by Steinman in 1972 found the main cables were in “generally very good condition” after investigators unwrapped them, then rewrapped them. But when the firm returned in 1979, inspectors discovered that cable wrap paint had “deteriorated considerably” and that caulking around the bands was no longer effective in sealing out water. The inspectors recommended a “major rehabilitation of the main cables” and replacement of the caulking.

The state responded to those recommendations four years later by resurfacing the deck, installing a center tie, replacing some suspenders, repairing an underwater pier, and repainting the entire bridge, including the cables. The recommended “major rehabilitation” of the cables was not part of the project.

Steinman performed another inspection in 1987. Although the engineers reported that the bridge and main cables were in “relatively good condition,” problems were detected once again. The report noted that water stains and rust were observed on the underside of the cables and recommended an “in-depth inspection” to determine the source of the water. Steinman continued to recommended “in-depth inspections” of the suspension system for the next three years.

DOT responded by hiring another engineering firm, Lichenstein Consulting Engineers of Paramus, N.J., to conduct the in-depth study. The study began in June 1990 and was completed in October 1992.

The study revealed that water had infiltrated the cables and that pitting of inner wires was detected. The firm recommended the bridge be strengthened by retrofitting it with cable stays. The firm also recommended that the cables be unwrapped and that the wires be cleaned and repainted.

The department hired Steinman in 1995 and its inspectors reported that water continued to flow within the cables and that the corrosion had increased since the last inspection. They recommended encapsulating the cables in a rubberlike wrap.

DOT reacted by including a major inspection of the bridge in the 1998-99 annual budget. The inspectors were asked to weigh the benefits of replacing the bridge or renovating it. Following a series of meetings and discussions on the various options, the department concluded that the bridge should be preserved and it committed $25 million to the project.

With its classic lines and parabolic arc, the bridge is an impressive sight whether approached from land, water or air. It has been cited by the American Society of Civil Engineers and is listed on the National Register of Historic Places. The bridge’s historical designation was one of the reasons DOT decided on a restoration project.

It was while DOT was replacing the suspension cables last winter that major deterioration of many of the 1,369 interior wires was discovered, including some that had broken apart. The department followed up this summer by posting the bridge to vehicles weighing more than 12 tons and recommending construction of a new bridge.

While he acknowledged that the situation could have been handled better over the years, Deputy Transportation Commissioner Bruce Van Note defended the department’s oversight of the bridge on Wednesday. He noted that more than 150 maintenance activities have been logged on the bridge since 1932, including 12 inspections by outside engineering firms.

Van Note told the Legislature’s Transportation Committee that the bridge was a complicated structure and that the early inspections were similar to looking at the sills of an old house. He said they might pass the initial inspection but fail a more detailed review.

“When we checked the sill it looked good,” Van Note said. “When we jacked up the whole house, that sill wasn’t good.”