A fatal crash on a span of Maryland’s Chesapeake Bay Bridge prompted an investigation, which found uncovered flaws in its Jersey walls. The 4.3-mile eastbound span is now undergoing emergency repairs, and more reconstruction may follow.
Several parapets were damaged during the Aug. 10 incident when an 18-wheeler struck a parapet, knocking part of it off the bridge, then skidded more than 100 ft along the wall before rolling into the bay. The truck driver was killed in the accident.
Radar inspections revealed small voids near the cores of the broken parapets, said Maryland Transportation Authority chief engineer Geoffrey Kolberg.
"The front faces looked great and about 4 inches in there was dense solid concrete, but when you got about 12 inches toward the center, there was not good consolidation with the concrete," he said.
The slip-formed parapets were constructed over two decades ago during a reconstruction project. Kolberg said the slip-form process is "one of the elements we're looking really closely at."
The finding led to radar inspection of similar parapets on the bridge. Following test results of the southeast and southwest walls, MTA is retrofitting those portions. Tests of the northeast and northwest walls are ongoing.
The retrofit plan consists of adding new steel brackets that would bolt each parapet to the bridge deck along the edge that faces traffic. A double "W" beam guardrail will be added to help with load share. The current system uses U-bolts to attach the bottom of each parapet through the concrete bridge deck to a steel plate below the deck.
"We're going belt and suspenders on this," Kolberg said.
If every parapet needs to be retrofitted, the project could take 10 weeks to complete, at a cost of $3 million. The project will be funded using MTA emergency reserves.
The bridge's westbound span had been undergoing a late-night re-decking project. Work on that project has been suspended.
