Design and Engineering MDTA and the Design-Builder began work on the design and preliminary engineering for all elements of the project in September 2024. In December 2024, the Design-Builder submitted Proof-of-Concept plans to MDTA (approximately 15% level of design completion) to validate key design assumptions made during the Federal Highway Administration (FHWA) National Environmental Policy Act (NEPA) Categorical Exclusion determination. In March 2025, the Design-Builder conducted the first of two phases of wind tunnel testing on the proposed cable stayed bridge design to evaluate its aerodynamic behaviour under high wind conditions. In late April 2025, the Design Builder submitted plans to MDTA for review at 50% level of design completion. Design is currently progressing to 70% level of design completion with a target for submission on December 1, 2025. The main bridge span over the navigation channel will be a 1,665-foot cable-stayed span between the main bridge piers with 850-foot back spans. In compliance with the USCG PNCD, the horizontal clearance between the pier protection that will surround the new main span piers will be no less than 1,100 feet. The main H-shaped towers supporting the cable stayed bridge will rise to a height of approximately 600 feet above the Patapsco River. The remaining bridge spans will include piers both in the Patapsco River and on both the approaches over land. Both the bridge and the bridge pier protection are being designed in accordance with the American Association of State Highway and Transportation Officials (AASHTO) Specifications.
The major construction elements of the project include:
• Removal of the existing bridge piers and a portion of the approach roadway from the north and south sides of the river. • Construction of the replacement bridge • Construction of pier protection • Reconstruction of the portions of the existing roadway at the north and south approaches, storm drain improvements, including new inlets, storm drain piping, and stormwater management facilities, including wet swales, grass swales, bioswales, micro-bioretention, and submerged gravel wetlands to meet Maryland Department of the Environment (MDE) and Chesapeake Bay Critical Area Commission requirements. • Bridge roadway and aesthetic lighting • Intelligent Transportation System (ITS), including virtual weigh stations, roadway weather information system, fog warning system and CCTV cameras In January 2025, the Design-Builder began subsurface geotechnical investigations in the river and on land. The information gathered from these efforts allows the Design-Builder to understand the subsurface conditions within the Patapsco River along the bridge alignment. Supplemental geotechnical investigations to gather additional information are complete. As part of these investigation efforts, a pile load test program is ongoing at both main span pier foundations. The load test program will verify the load bearing capacity and behavior of the foundation piles which support the cable stayed bridge structure. To better understand and estimate the potential scour at the proposed bridge foundations, FHWA’s Turner- Fairbank Highway Research Center, in cooperation with MDTA and Maryland State Highway Administration (SHA), has performed
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