Transportation
New Design for Francis Scott Key Bridge Replacement Unveiled
The two-mile-long bridge will provide greater vertical and horizontal clearances to accommodate increasingly large vessels
The new two-mile-long bridge Key Bridge in Baltimore will be longer and higher than its 1970s-era steel arch continuous truss predecessor.
Photo courtesy MDTA
Maryland officials have debuted the initial design concept for the Francis Scott Key Bridge rebuild—a two-mile-long, cable-stayed structure that will be the first of its kind in the state.
Designed by Kiewit Infrastructure Co. under the $73-million first phase of a progressive design-build contract with the Maryland Transportation Authority (MDTA), the bridge will be longer and higher than its 1970s-era steel arch continuous truss predecessor, providing greater vertical and horizontal clearances to accommodate the increasingly large vessels calling on the Port of Baltimore. The design calls for the two 600-ft-tall main span pylons to be separated by a more than 1,600 ft, with the bridge deck height above the main deep-draft shipping channel of at least 230 ft.
The original 1.7-mile steel bridge, which collapsed after being struck by the disabled neo-Panamax container vessel M/V Dali in the early morning hours of March 26, 2024, provided only 1,209 ft of horizontal clearance between the main spans, and 185 ft of vertical clearance above the channel. The new bridge’s cable-stayed main span will exceed 3,300 ft, an increase of more than 600 ft over the original continuous truss span length.
The new bridge will occupy the same footprint across the mouth of Baltimore harbor, restoring the Baltimore Beltway with two 12-ft lanes in each direction, and 10- and 4-ft wide outside and inside shoulders, respectively. Maryland officials say that the structure also will feature the latest in pier protection technology—the absence of which on the original Key Bridge may have contributed to the structure’s collapse.
According to the National Transportation Safety Board’s preliminary report, the original bridge included four large dolphins to protect the pylons supporting the central through-truss spans. Each dolphin was composed of 25-ft-diameter sheet pile filled with tremie concrete and capped with reinforced concrete. The dolphins were fitted with 17-ft-long rubber fenders at various locations. Each of the main pylons also was surrounded by a 100-x-84.5-ft crushable concrete box and timber fender system.
NTSB’s report says that while the Dali struck the pylon’s fendering system at 6.5 knots, it missed the nearest dolphin, located approximately 491 ft upstream of the pylon and 550 feet clear of the centerline of the navigational channel’s centerline. The impact caused six spans to collapse into the water and across the vessel’s bow, killing six construction workers who had been performing concrete deck repairs at the time. NTSB has not said when it expected to complete its investigation of the incident, which closed the Port of Baltimore for several months and continues to disrupt traffic in and around the city.
With the new design concept, MDTA says the project will move forward with the second phase of the progressive design-build process, which includes final design, demolition of the remaining original Key Bridge structures, and construction. Kiewit will have exclusive negotiating rights for this work, expected to cost $1.7 billion. No timeline for the phase 2 has been announced, other than the scheduled completion target of fall 2028.
Preconstruction surveys and soil sampling began in January.
