NTSB Chair Homendy: MDTA Failed to Assess Key Bridge Structural Risks

NTSB's Vulnerability Assessment of Key Bridge

• 💡 The NTSB conducted its own vulnerability assessment of the Francis Scott Key Bridge to determine its susceptibility to collapse from a vessel collision.
• 🧠 This assessment used a mathematical risk model, a methodology developed by AASHTO in 1991 following the Sunshine Skyway Bridge collapse.

AASHTO Guidance and MDTA's Failure

• 📌 AASHTO recommended in 1991 and reiterated in 2009 that all bridge owners conduct vulnerability assessments for existing bridges over navigable waterways.
• ⚠️ The guidance stated that these assessments should identify and rank high-risk bridges for potential rehabilitation or protective measures.
• 🚫 The Maryland Transportation Authority (MDTA) never conducted this vulnerability assessment on the Key Bridge, and as of October 2024, still has not.

Critical Risk Thresholds Ignored

• 📈 Had the MDTA performed the calculation, they would have known the Key Bridge was almost 30 times greater than the risk threshold set by AASHTO for critical bridges.
• 🎯 For Pier 17, which the Dali struck, and Pier 18, the risk was almost 15 times greater than the threshold.

Data Deficiencies and NTSB's Efforts

• 📊 The MDTA also failed to provide the NTSB with crucial data needed for the assessment, including vessel traffic characteristics, speeds, loading, waterway geometry, and bridge protection systems.
• 🤝 The NTSB, with assistance from the Federal Highway Administration, had to develop this data independently.

Proactive Risk Reduction Missed

• 🚀 The report concludes that if the MDTA had conducted the vulnerability assessment, they could have proactively identified strategies to reduce the risk of collapse and loss of life.
• 🔍 The NTSB also surveyed other bridges across the US that cross navigable waterways with oceangoing vessel traffic to understand the scope of similar risks nationwide.