Key Elements of the New Bridge
To put the magnitude of the Key Bridge Rebuild into perspective, here are some of the major construction components that make up one of the largest cable-stayed bridges in the United States.
New Bridge
- The rebuilt bridge includes the main span cable-stayed bridge and marine and land approach spans that connect the bridge to land on each side.
- The total bridge length is 11,015 feet, over half of which requires marine construction.
- The structure are nearly 98,000 square yards of concrete bridge deck.
Typical Road Section
- The roadway has two 12-foot lanes in each direction, with a 10-foot outside shoulder and 4-foot inside shoulder, meeting Interstate standards.
- A 5-foot maintenance walkway runs along each side of the cable-stayed span, with cables set back from traffic for safety and improved wind stability.
- Barriers are 42” tall to comply with current safety standards.
- Anti-climb fencing over the water and street lighting are included for additional safety and visibility.
Cable Stayed Bridge
- The cable-stayed bridge is 3,365 feet long and supported by six piers, including the two main pylons.
- The 1,665-foot main span will be the longest cable-stayed span in the U.S. and provides 230 feet of clearance for marine traffic.
- The bridge is supported by 144 cables, which will distribute the deck’s weight evenly.
Pylons
- Each pylon tower rises over 600 feet above the river, with a column that tapers as it ascends.
- The lower tower sections include over 4,300 cubic yards (≈8,600 tons) of reinforced concrete for strength and stability.
- The towers are connected by two concrete struts (each 20′ x 20′ and 95 feet long): the lower beam is solid, and the upper beam is a hollow box with 2-foot-thick walls.
- Each tower is constructed in 31 concrete lifts, each 15–20 feet tall.
Pylon Foundations
- Each foundation is supported by 45 massive steel piles, each over 200 feet long and 8 feet in diameter, anchored deep into the Patapsco geological layer.
- The footing itself is roughly the size of two NBA basketball courts and stands 20 feet thick.
- More than 13,000 cubic yards of concrete—about 26,600 tons—goes into each footing.
- Constructing each foundation takes over 1,300 truckloads of concrete, placed in three layers.
Cable Stayed Bridge Foundations
- The cable-stayed bridge foundations include six total piers.
- This includes the two main pylons along with a tie-down and transition pier on each side of the main span.
- Tie-down piers and transition piers each have 10 steel piles that are 8 feet in diameter in every foundation.
- In total, the cable-stayed bridge foundations use 130 piles, each 8 feet in diameter.
Pier Protection System
- Each main pylon protection fender is longer and wider than an NFL football field and over 20 feet thick, containing ~41,600 cubic yards (≈83,000 tons) of reinforced concrete.
- Each of these foundations is supported by 78 steel pipe piles, each 8 feet in diameter and filled with ~144 cubic yards (≈288 tons) of concrete.
- The other four cable-stayed pier protection fenders are smaller but similar, containing ~21,000–23,000 cubic yards (≈42,000–47,000 tons) of concrete.
- In total, the bridge’s vessel protection system uses 276 concrete-filled steel piles, each 8 feet in diameter.
Approach Spans
- The marine approach spans total 2,219 feet, with a bridge deck area equal to just over 3 football fields.
They include 7 curved steel girder spans, each about 300–330 feet long, supported by 7 two-column piers.
Their foundations use 48-inch steel pipe piles, with 126 total piles, with the upper portions filled with reinforced concrete. - The land approach spans total 5,431 feet with a bridge deck area equal to about 8 football fields.
- They include 36 concrete girder spans, each 150 feet long, supported by 36 two-column piers ranging from 24 to 124 feet tall.
- The foundations will use 36-inch steel pipe piles, with 648 total piles driven deep into the ground.
Latest Renderings
Design Related News
Bridge Design FAQ
The new bridge will be Maryland’s first highway cable-stayed bridge, which will consist of two lanes in each direction and have a minimum vertical clearance of 230 feet to support larger vessels. It will be constructed according to current industry standards and infrastructure design practices. Cable-stayed bridges have proven to be the most economical for bridges with similar span lengths and allow for a faster construction time compared to other complex bridge types.
There will be two 12-ft lanes with a 10-ft outside shoulder and a 4-ft insider shoulder in each direction, separated by a concrete median.
The bridge piers will be protected by pier protection structures, which will be designed per the latest American Association of State Highway and Transportation Officials (AASHTO) specifications and follow best practices for modern vessel collision protection. Additionally, the main span length of the bridge has been increased to provide additional clearance from the shipping channel.
The images for the Key Bridge design are artistic renderings and do not necessarily reflect all features.
Updated images will be posted as they become available.
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