ANNAPOLIS, Md. – Without saying who is to blame, a report released Thursday by an independent panel concluded that a combination of rushed work and inadequate planning was the cause of bungled repairs on the Chesapeake Bay Bridge.

At least $7 million worth of repaving work must be redone, and State Transportation Secretary Bob Flanagan said Thursday that the project won’t be finished by spring 2006, as originally planned. Work began on about 2 miles of the bridge in 2002 and was estimated to cost $70 million.

The crux of the problem, the panel found, is that the long, thin westbound span of the bridge presented a more complex repair job than state officials, engineers and contractors planned.

Much of the concrete decks on the bridge are only 6.5 inches thick, at least an inch thinner than most long-span bridges. The unusual structure requires “robust and meticulous” methods of repaving – methods that Maine-based Cianbro Corp. did not follow, said panel chairman Thomas Deen, a Stevensville engineer who is a retired executive director of Transportation Research Board, a division of the National Research Council of the National Academies of Science and Engineering.

The timing of the work contributed to the problems, the report found.

The Maryland Transportation Authority, which oversees bridge operations, required that the work be done outside the busy summer season, in off-peak hours and mostly on one lane at a time.

“It came out of the best intentions – to avoid inconveniencing our customers,” Flanagan said.

Contractors were further limited by the weather, because cold temperatures and high wind hinder concrete’s ability to set. The concrete usually should be used when temperatures are at least 40 degrees, but some of the mix was poured in temperatures as low as 29 degrees, Deen said.

“Standards with respect to temperature were probably bent too far,” he said.

The attempts to “expedite production” contributed to “critical weaknesses” in the overlays, the report states.

The deficient lengths of the span already have been replaced or will be replaced by Memorial Day. And the overlays will last about 10 years, Deen said.

But he and his panel strongly urged the state to ditch any major repaving on the 31-year-old deck in the future and instead replace the full depth of the bridge decks – a much more expensive and disruptive project, but one that would be more durable.

The report identified several reasons why the new concrete on the westbound span failed, including:

. The underlying surface of the bridge wasn’t adequately prepared for the new concrete.

. The concrete wasn’t mixed properly.

. An epoxy bonding agent was misused.

In compiling the 61-page report, the committee questioned engineers for Maine-based Cianbro Corp., the contractor that has been working on the bridge since 2002. But Flanagan is waiting for an investigation by the state attorney general’s office to determine who is to blame for the mistakes in the work and if anyone is liable for the cost of redoing the fouled-up work.

The team also recommends that the state “pre-qualify” all consultants, contractors and suppliers for any future work on the bridge. Because the bridge’s structure is unusual and complicated, it requires the most experienced engineers and the best materials, the report found. The state should require those working on the bridge to submit their qualifications at least six months before starting new work on the bridge.