Problems occurred in resurfacing concrete deck of westbound
bridge (left) (Photo by Dan Breitenbach/Maryland Transportation Authority)

At least five separate errors combined to badly damage sections of the recently resurfaced parts of the Chesapeake Bay Bridge, according to a new report.

The concrete resurfacing project was done on the bridge's thin deck, which also contributed to the delamination woes, according to an independent review panel. But its report also cited inadequate surface preparation of the deck substrate, use of an epoxy material applied to the substrate, use of silica-fume concrete mixtures, placement of concrete in cold temperatures and use of a sprayed curing compound.

In the wake of the panel's report, released Feb. 10, Maryland Transportation Secretary Robert L. Flanagan says state officials will take "a fresh approach" to the next phase of $76-million project to rehabilitate the deck of one of the two, four-mile-long bridges that cross the bay. The details of that new approach won't be determined until tests of the deck are completed and analyzed, but Flanagan says the project's original 2006 completion date now is likely to extend into 2007.

Regarding potential costs, Flanagan says, "We are clearly opening up for consideration using a different process for the work that may have a different price." But he adds that discussions with industry may produce ways to reduce the cost.

Flanagan noted that the committee wasn't charged with assessing blame for the problem, but said the state attorney general's office would deal with "allocation of responsibility."

Mike Hart, vice president and Mid-Atlantic regional general manager for project contractor Cianbro Corp., told ENR that "generally if you read the report in its entirety...we feel it substantiated what we said before--we did this work per the contract specifications and per our client's direction." Hart says his comment also refers to work done by Cianbro's subcontractors. He adds that Cianbro plans to issue a detailed statement regarding the review team's report later in the week of Feb. 14.

At issue is the deck of the three-lane westbound bridge, which was completed in 1973. It sits parallel to the 53-year-old bridge that carries traffic eastbound. Traffic volume averages about 65,000 vehicles daily, more than triple the level of 30 years ago. Phase one of the rehabilitation contract, awarded in 2001 to Cianbro Corp., Pittsfield, Maine, called for new concrete overlays on 95 spans totaling about 12,400 ft., plus complete deck replacement on 21 spans covering 3,900 ft. Cianbro was the only bidder on the phase one contract, which initially was $33.5 million and then increased to $43.5 million. Phase two will deal with the westbound bridge's other eight spans, which extend for 6,700 ft.

Overlay work started in 2002, but the following year cracks started to appear in some of the repaved sections. Cracks became more widespread in 2004 and prompted Flanagan to recruit a team of outside specialists, led by former Transportation Research Board Executive Director Thomas B. Deen, to find out what went wrong. As the team dug into the issue, tests it requested turned up a second problem--concrete deterioration on sections of the deck's underside. So far, no connection has been found between the overlay and underside problems, state officials say.

Flanagan, who also chairs the Maryland Transportation Authority, the state DOT unit that operates the bridge, said that the overlay and deck underside problems "are not safety issues. These are durability issues."

In its report, the review panel recommended that the state: weigh full-depth deck replacement, at least for some sections of the bridge; prequalify design firms, contractors and materials suppliers; and consider using rapid-set, latex-modified concrete. Deen said he didn't expect that full-deck replacement would be needed on the entire westbound bridge. He says the problem appears to be concentrated in parts of the deck that are 6.5 inches thick. That 6.5-in deck occurs on the bridge's long spans, which account for two-thirds of its four-mile length. The rest of the bridge has a 7-inch-thick deck.

The report notes that the decks are "considerably thinner than most decks built today, which typically have a minimum thickness of 8 in." It adds that the thin decks, flexibility of the longer spans and traffic load subject the spans "to higher than normal stresses, making it essential that the overlay functions as an integral part of the deck structure."

The panel also included an appendix with 21 highly specific recommendations for doing the overlay work, including a ban on applying matrix restorer or epoxy adhesive to the prepared deck surface and requiring the clean blasted surface should be wet down for at least one hour and kept wet for at least three hours before the overlay is applied.

The report observes that there inevitably are exceptions made to procedures on construction projects, but it adds, "In the case of the Bay Bridge, it appears that there were a particularly large number of exceptions and non-standard practices in a situation where meticulous adherence to best practice was a necessity for good results."

Elsewhere in its 66-page report, the review panel says all of the phase one overlays with known deficiencies have been replaced or will be by the end of the first phase, in spring of this year. But it adds that "sooner or later, the [Maryland Transportation Authority] will face the need to do full-depth replacement when the Phase 1 overlays reach the end of their service lives."

That full-depth plan should consider cast-in-place and prefabricated approaches, it says, noting that a mix of the two construction methods may be appropriate. It recommends a two-step plan for the full-depth replacement, with the first step defining the spans that should be cast-in-place and those that should be prefabricated. In step two, potential bidders, traffic, public-outreach and engineering specialists would get comment on and suggest changes in the results of step one.

Flanagan said that current overlay work on the westbound bridge's center lane would be completed in the spring and work may be done in the fall. That includes some "first-time resurfacing" and possibly some rework, he adds.

Developing a new plan will delay the project. Flanagan said that the target to finish the job by spring 2006 "is not at this point a realistic target." He said it is likely to carry into 2007. But he said officials hope to plan the job in a way that's more "user friendly," and avoid lengthy delays to motorists.

Deen says that on a bridge project wind can dry the concrete surface before it's properly cured and cause cracking. He says, "There was great pressure to try to get the job done....Standards with respect to temperature were probably bent too far." He says that the normal minimum temperature for such resurfacing was 40 to 45 degrees, but some of the work on the Bay Bridge was done at temperatures as low as 29 degrees, "But," he adds, "it's not obvious to me...whose fault that is, if anybody's." He says he didn't know what the temperature specifications were, and whether there were modifications or waivers.

Regarding Deen's comment about pressure to complete the project, Flanagan says, "I didn't push anybody, personally. But I think that everyone who works at the transportation authority has a high level of consciousness of our customers and the fact that as a matter of...unavoidable course, people wait hours to cross that bridge." He adds, "It came from the best of intentions--that is, to avoid inconvenience to our customers--but somehow those good intentions did not end up with the best results."

Flanagan said one of the panel's key recommendations was that "we need to work better with people in the construction industry to get information from them about how to plan this work." He said the state would tell firms: "Look, here is the result that we want to obtain. We want a healthy bridge. We want a rehabilitated bridge. But before we get you the plans and specifications we want to hear from you as to how this work can be done from a practical construction point of view."