Key Bridge Collapse, Baltimore 2024: How One Allision Closed a Major Port

The short version

This explainer asks one island-relevant question: what happens when a single structure closes the only deep channel into a major port, and what does that teach places that already run on one harbor? It sits in ISPI’s ports and maritime security research hub and its supply chain and infrastructure hub, and it expands the Baltimore half of the planned dual case on ports as single points of failure. The Beirut 2020 half of that dual piece remains for a later post.

Baltimore is not an island. It is, however, a clear example of a single-point-of-failure channel. The Francis Scott Key Bridge carried I-695 over the Patapsco River and sat astride the Fort McHenry Federal Channel. When the span came down, deep-draft access to the Port of Baltimore stopped until salvors cleared the wreckage. That is the same geometry Hawaiʻi lives with at Honolulu Harbor, and that many Caribbean and Pacific islands live with at their only commercial berth.

What happened on March 26, 2024

According to the National Transportation Safety Board, about 0129 local time on March 26, 2024, the Singapore-flagged containership Dali was leaving Baltimore Harbor when it lost electrical power, propulsion and steering and struck Pier 17, the southern pier that supported the central span of the Key Bridge. A substantial portion of the bridge collapsed into the river; portions of the pier, deck and truss fell onto the vessel’s bow and forward container bays (NTSB investigation DCA24MM031; NTSB Marine Investigation Report MIR-25-40).

A seven-person road maintenance crew and one inspector were on the bridge. Six highway workers died. One highway worker survived with serious injuries; the inspector escaped unharmed. One of the 23 people aboard the Dali had a minor injury. Damage to the Dali exceeded $18 million; cargo damages were undetermined (NTSB investigation DCA24MM031).

The NTSB’s final marine investigation report, MIR-25-40, approved at a board meeting on Nov. 18, 2025, estimated bridge replacement at $4.3 billion to $5.2 billion and anticipated opening to traffic in late 2030. More than 34,000 vehicles a day, 10 percent of them trucks, that formerly used the Key Bridge must now take alternate routes; the bridge was also the primary route for hazardous-materials vehicles that cannot use the tunnels under Baltimore’s waterways (NTSB Marine Investigation Report MIR-25-40; NTSB press release, Nov. 18, 2025).

Why the NTSB says it happened

The NTSB determined that the probable cause was a loss of electrical power (blackout) from a loose signal wire connection to a terminal block, stemming from the improper installation of wire-label banding, which left the vessel without propulsion and steering close to the bridge (NTSB investigation DCA24MM031; NTSB Marine Investigation Report MIR-25-40). Contributing to the crew’s inability to recover propulsion was the limited time available because of the Dali’s proximity to the bridge.

Contributing to the collapse and the loss of life, the NTSB found, was the lack of countermeasures that would have reduced the bridge’s vulnerability to impact by ocean-going vessels—measures that could have followed a vulnerability assessment by the Maryland Transportation Authority under longstanding American Association of State Highway and Transportation Officials guidance. Also contributing to the loss of life was the lack of effective and immediate communications to notify the highway workers to evacuate (NTSB investigation DCA24MM031).

The NTSB’s Nov. 18, 2025 press release notes that the Key Bridge is 2.37 miles long and opened in 1977, and that vessel size has grown since then: when the Japan-flagged containership Blue Nagoya contacted the same bridge after losing propulsion in 1980, the 390-foot vessel caused only minor damage, while the Dali is about ten times that size (NTSB press release, Nov. 18, 2025). The board issued urgent and ordinary recommendations to the Coast Guard, Federal Highway Administration, AASHTO, multiple bridge owners, classification and standards bodies, the vessel manager and the terminal-block manufacturer (NTSB investigation DCA24MM031).

How one channel closed a major port

The operational problem for commerce was not only the fallen span. It was the wreckage sitting in the Fort McHenry Federal Channel, the deep-draft federal navigation channel into the Port of Baltimore. USACE describes that channel’s original operational dimensions as 700 feet wide and 50 feet deep (USACE Baltimore District, June 10, 2024).

On April 4, 2024, USACE published a tentative timeline: a limited-access channel about 280 by 35 feet within about four weeks to support one-way barge container and some roll-on/roll-off traffic, and an aim to restore the permanent 700-by-50-foot channel by the end of May, subject to weather and wreckage complexity (USACE, April 4, 2024). Actual milestones, as USACE recorded them on June 10, ran close to that plan and finished with full restoration on June 10 rather than by the end of May (USACE Baltimore District, June 10, 2024).

The June 10 survey certified the riverbed safe for transit after wreckage removal at the 50-foot mud line. USCG Sector Maryland-NCR’s Marine Safety Information Bulletin 052-24 reopened the Fort McHenry Channel to commercial traffic for 24-hour availability at the restored 50-foot depth, 700-foot horizontal clearance and 214-foot vertical clearance (limited by adjacent power lines). Deep-draft vessels still required a Maryland State Pilot; temporary alternate channels stayed available while salvage finished (USCG Sector Maryland-NCR MSIB 052-24 (via USACE navigation notice); MDOT Maryland Port Administration, June 11, 2024).

The Unified Command that cleared the channel included the U.S. Coast Guard, USACE, Maryland Department of the Environment, Maryland Transportation Authority, Synergy Marine’s representative and Maryland State Police. At its peak it led about 56 federal, state and local agencies and 1,587 individual responders, with about 500 specialists operating 44 vessels, 36 barges, 27 tugboats, 22 floating cranes and other plant; about 50,000 tons of bridge wreckage came out of the Patapsco River (USACE Baltimore District, June 10, 2024).

What the disruption cost the Port of Baltimore

Maryland’s published cargo figures show both the hit and the rebound. In 2023 the Port handled a record 52.3 million tons of cargo. In 2024, despite the allision and channel closure, it handled 45.9 million tons—still the second-best year on record—with more than 25.5 million of those tons moving in the second half of the year after the channel reopened. Cargo value in 2024 was $62.2 billion. The Port generates about 20,300 direct jobs and more than 273,000 jobs linked to Port activities (Office of Governor Wes Moore, Feb. 25, 2025).

Governor Moore’s February 2025 release states that but for the Key Bridge collapse, 2024 would likely have been even stronger, and that the Port finished the year tenth nationally for total cargo and eleventh for dollar value among U.S. ports (Office of Governor Wes Moore, Feb. 25, 2025). Those are Maryland’s figures; they do not by themselves isolate diverted cargo that stayed at other East Coast ports. For island planners, the useful point is simpler: even a large U.S. port with alternate East Coast options lost a measurable share of a record year when its deep channel closed for roughly eleven weeks.

What this means for island and single-port economies

ISPI’s lens on water-bound places is single points of failure: one port, one channel, one fuel terminal, one bridge. Baltimore had a large hinterland and competing East Coast ports. Most island capitals do not. Hawaiʻi moves almost all commercial goods through Honolulu Harbor’s hub-and-spoke system, as ISPI’s explainer on Honolulu Harbor and the single-port state sets out. Caribbean sister islands in the Hurricane Beryl case study lost ferry terminals and airstrips while main ports reopened. Pacific islands that import food and fuel through one wharf face the same geometry without a Norfolk or New York next door.

Five lessons travel cleanly from Baltimore to island COOP and port security work:

• Map the channel, not only the berth. The Port of Baltimore’s terminals were intact; the federal channel was not. Island risk registers should mark the controlling depth, the single span or reef pass that protects it, and the first alternate draft that can still move fuel, food and medicines (USACE Baltimore District, June 10, 2024; continuity of operations guide for island local government).
• Stage the reopen. USACE and the Coast Guard did not wait for full restoration. Temporary alternate channels for shallow draft opened within a week; a limited-access deep channel followed; full dimensions came last (USACE Baltimore District, June 10, 2024). Island port plans should pre-agree the order of temporary lanes, draft limits and pilot rules with the harbor master and coast guard equivalent.
• Divert cargo on paper before the crisis. Baltimore could send boxes to other East Coast ports. An island that loses its only deep berth needs a written diversion list: nearest alternate port, air freighter options, stock days for fuel and staples, and who decides. That is the same discipline ISPI describes under supply chain singularity and in the freight-shock planning in the analysis of Red Sea diversions and island import costs.
• Treat bridge and pier protection as port security. The NTSB found missing vessel-collision vulnerability assessment and missing immediate worker alerts contributed to the collapse and the deaths (NTSB investigation DCA24MM031). Island bridge and jetty owners should run the same AASHTO-style check even when the span looks local.
• Keep continuity plans current. Eleven weeks of constrained access is long enough to empty shelves on a small island. Pair the channel plan with the continuity of operations guide for island local government and the emergency preparedness hub.

Distant shocks already reach islands through freight rates, as the maritime chokepoints explainer and the Red Sea record show. A local allision or storm that closes the home channel is a harder test, because there is no hinterland port to absorb the ships. Baltimore is the measured case of how fast that failure arrives and how a staged federal response rebuilds the waterway.

Frequently asked questions

When did the Key Bridge collapse and when did the deep channel reopen?

The Dali struck the Francis Scott Key Bridge about 0129 local time on March 26, 2024. The U.S. Army Corps of Engineers and partners restored the Fort McHenry Federal Channel to its original 700-by-50-foot dimensions on June 10, 2024, and the Coast Guard reopened 24-hour commercial transit the same day.

What did the NTSB say caused the allision?

The probable cause was a loss of electrical power from a loose signal wire connection to a terminal block, caused by improper installation of wire-label banding, which left the Dali without propulsion and steering close to the bridge. Limited recovery time, missing bridge collision countermeasures and missing immediate alerts to highway workers contributed to the collapse and the deaths.

How many people died?

Six highway workers on the bridge died. One highway worker was seriously injured; the inspector on the bridge was unharmed. One of the 23 people aboard the Dali had a minor injury.

Did the Port of Baltimore stop all cargo for the whole period?

Deep-draft access through the Fort McHenry Federal Channel was blocked until June 10, 2024, but temporary alternate channels for shallow-draft vessels opened from April 2, and a limited-access channel for some deep-draft and roll-on/roll-off traffic opened in late April and was widened in May. Maryland reports 45.9 million tons of cargo for full-year 2024, down from the 2023 record of 52.3 million tons.

Why does this matter for island governments?

Many islands depend on one deep channel or one commercial harbor. Baltimore shows that an intact terminal is not enough if the approach channel is blocked, and that temporary lanes, cargo diversion and continuity planning have to be ready before the incident.

ISPI publishes its research free under CC BY 4.0. If your government, port authority or emergency management agency needs a single-channel exposure review, a port continuity tabletop or a cargo-diversion plan for an island harbor, you can commission research from ISPI. ISPI is a nonprofit organization with its 501(c)(3) application pending.

Sources

1. National Transportation Safety Board, Contact of Containership Dali with Francis Scott Key Bridge and Subsequent Bridge Collapse (investigation DCA24MM031)
2. National Transportation Safety Board, Marine Investigation Report MIR-25-40, Contact of Containership Dali with Francis Scott Key Bridge and Subsequent Bridge Collapse (PDF; board meeting Nov. 18, 2025)
3. National Transportation Safety Board, Loose Wire on Containership Dali Leads to Blackouts and Contact with Baltimore’s Francis Scott Key Bridge (press release), November 18, 2025
4. U.S. Army Corps of Engineers, Baltimore District, U.S. Army Corps of Engineers announces full restoration of Baltimore’s Fort McHenry Federal Channel, June 10, 2024
5. U.S. Army Corps of Engineers, U.S. Army Corps of Engineers develops tentative timeline to reopen Fort McHenry Channel following Key Bridge collapse, April 4, 2024
6. U.S. Coast Guard Sector Maryland-NCR, Marine Safety Information Bulletin 052-24, Fort McHenry Channel reopened (June 10, 2024), via USACE navigation notice Update-07
7. MDOT Maryland Port Administration, Correction — Fort McHenry Channel Reopened To Full Width And Depth, June 11, 2024
8. Office of Governor Wes Moore, Governor Moore Announces Port of Baltimore Recovery Milestone Following Key Bridge Allision and Collapse, February 25, 2025
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