A Johns Hopkins University engineering team is warning that dozens of major U.S. bridges face elevated ship-strike risk on an annual basis, a finding that gained urgency after the Francis Scott Key Bridge in Baltimore collapsed on March 26, 2024. In the NTSB’s investigation of the incident, the containership Dali experienced electrical blackouts that led to a loss of propulsion and steering before the allision, while investigators also highlighted the absence of certain bridge protections that can reduce vessel-strike consequences. The researchers’ broader concern is probabilistic: without upgrades at vulnerable crossings, the odds of repeated major bridge-strike disasters over time rise sharply.
How a Loose Wire Brought Down a Bridge
At about 0129 local time on March 26, 2024, the 984-foot containership Dali was transiting outbound through the Patapsco River when it lost power. The National Transportation Safety Board traced the failure to a loose wire that caused repeated electrical blackouts aboard the vessel. Those blackouts knocked out propulsion and steering, leaving the fully loaded ship drifting toward the Key Bridge with no way to stop or turn.
The Dali struck one of the bridge’s support piers, and the span collapsed within seconds. The federal government classified the event as a major marine casualty, and the Port of Baltimore was forced to close. The port closure rippled through regional supply chains and commuter routes, illustrating how a single point of failure on one vessel can paralyze an entire metropolitan freight network.
Federal Investigators Found No Protective Barriers
The NTSB investigation did more than examine the Dali’s electrical problems. It also emphasized that protections such as pier protection systems and other vessel-strike countermeasures can reduce the consequences of an allision, and it urged bridge owners to evaluate whether their bridges need additional safeguards. The point is significant because it broadens the post-incident focus beyond the ship to infrastructure risk management and safety standards for bridges over navigable waterways.
In a report issued on March 18, 2025, the NTSB went further, urging bridge owners nationwide to evaluate and install safeguards against vessel strikes. The agency’s language was direct: bridges over busy shipping lanes need physical and operational defenses, and many do not have them. The full accident docket contains technical documentation supporting these conclusions, including detailed records of the Dali’s electrical system failures and the bridge’s structural vulnerabilities.
Most public discussion after the collapse focused on the ship’s mechanical problems. But the NTSB’s emphasis on missing countermeasures points to a systemic issue that predates the Dali’s voyage. Bridges built decades ago were designed for smaller vessels and lower traffic volumes. The Key Bridge, completed in 1977, was never retrofitted to account for the massive container ships that now routinely pass beneath it. That mismatch between aging infrastructure and modern shipping realities is at the core of the expert alarm.
The investigation also highlighted the value of modern data tools. The NTSB maintains a searchable online docket system that allows engineers, policymakers, and the public to review evidence from accidents like the Key Bridge collapse. By making technical findings accessible, the agency provides a factual basis for debates over how aggressively to harden critical crossings.
Johns Hopkins Risk Assessment Identifies Widespread Danger
The Key Bridge collapse prompted researchers at Johns Hopkins University’s Department of Civil and Systems Engineering to conduct a broader bridge-strike analysis across the country. Their work applied a key design-standard concept: annual collapse probability targets for bridges should be extremely low, especially where failure would cripple major transportation corridors.
When the team measured actual conditions at bridges spanning busy waterways, many structures fell well short of that standard. The assessment identified multiple high-risk bridges where vessel traffic patterns, bridge geometry, and the absence of protective infrastructure combine to create unacceptable odds of a strike. The implication is stark. If annual collapse probabilities at these sites remain above safe thresholds, a disaster on the scale of the Key Bridge failure is not a freak event but a statistical expectation over time.
This is the “yearly shipping disaster” scenario experts are flagging: not that a bridge will definitely fall every year, but that the cumulative annual risk across all vulnerable sites makes repeated catastrophes likely without corrective action. The researchers stress that probability compounds. A one-in-a-thousand annual collapse risk may sound small for a single bridge, but multiplied across dozens of structures and decades of service life, the chance of at least one failure becomes uncomfortably high.
What separates this assessment from typical post-disaster hand-wringing is its grounding in engineering probability rather than speculation. The researchers are not simply saying bridges are old. They are quantifying how far specific structures deviate from accepted safety benchmarks, giving policymakers a measurable basis for prioritizing upgrades. That shift from anecdote to quantification is crucial for deciding where limited infrastructure dollars should go first.
Restoring a Waterway After Catastrophe
While engineers studied long-term risk, NOAA’s Office of Coast Survey worked to reopen the Patapsco River channel. The agency’s emergency charting work involved updating electronic navigational charts, conducting hydrographic surveys of the debris field, and mapping the altered channel to ensure safe passage for commercial vessels. That work had to happen before any ship could safely transit the area again.
The NOAA effort reveals a hidden cost of bridge collapses that goes beyond the immediate loss of life and infrastructure. When a bridge falls into a shipping channel, the waterway itself becomes unusable until federal agencies can survey the wreckage, update charts, and certify new safe navigation routes. Every day a channel remains closed, cargo diverts to other ports, trucking costs rise, and regional economies absorb losses that compound quickly. For communities that depend on maritime trade, this is the practical consequence: a bridge collapse does not just destroy a road, it blocks a river.
Those downstream impacts reinforce the Johns Hopkins warning. If the nation tolerates elevated strike risk at multiple key crossings, it is also accepting the prospect of repeated, prolonged closures of major waterways. The economic shock from a single event like the Key Bridge collapse is substantial; multiplied over several incidents, it could reshape trade flows and strain already fragile supply chains.
The Gap Between Known Risk and Action
The available evidence creates an uncomfortable picture. The NTSB has documented that the Key Bridge had no countermeasures. Johns Hopkins researchers have shown that other bridges face similarly elevated annual strike probabilities. And the NOAA response demonstrated how expensive and time-consuming it is to restore a waterway after a collapse. Yet there is still a lag between what engineers say is necessary and what agencies and legislatures have so far committed to fund.
Part of the challenge is visibility. Protective structures such as fender systems, dolphins, or artificial islands are often submerged or unobtrusive, making them easy targets for budget cuts compared with more visible projects like new lanes or aesthetic upgrades. Another obstacle is jurisdictional complexity: responsibilities for bridges, channels, and navigation safety are spread across federal, state, and local entities, complicating unified planning.
Experts argue that closing this gap will require treating ship-strike protection as a core design requirement, not an optional add-on. That means embedding vessel impact analysis into routine bridge inspections, updating design codes to reflect modern ship sizes and traffic densities, and prioritizing retrofits at crossings where a collapse would sever critical freight or commuter routes. It also means using tools like the NTSB’s public dockets and academic risk models to identify the most urgent vulnerabilities rather than waiting for the next disaster to reveal them.
The collapse of the Francis Scott Key Bridge was triggered by a single loose wire, but the broader story is about systemic exposure. Without deliberate investment in protective measures and better risk management, the United States will continue to rely on aging bridges that were never built for the ships passing beneath them. The engineering verdict is increasingly clear: unless that calculus changes, another catastrophic strike is not a matter of if, but when.
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*This article was researched with the help of AI, with human editors creating the final content.
