Case Study: Tappan Zee Bridge Crane Collapse (New York, 2016)
Project Overview
• Name: New Tappan Zee Bridge Pile Installation
• Location: Hudson River, Westchester County, New York
• Year: 2016 (July 19)
• Project Size: Part of multi-billion-dollar bridge replacement program
• Scope: Installation of deep pilings using a towering crane mounted on temporary platforms adjacent to the existing bridge
• Lead Agencies/Contractors: New York State Thruway Authority /
Category of the Issue, Problem, or Challenge
• Equipment Failure
• Geotechnical
• Safety Management
Summary of the Issue, Problem, or Challenge
On July 19, 2016, a 25-story construction crane deployed to drive pilings into the Hudson River suddenly collapsed during routine work. Neither high winds nor severe weather were present. Operator error was ruled out. Preliminary theories pointed to ground instability—encountering a soft spot during piling led to rapid settlement, which caused the crane hammer to drop abruptly, overloading and buckling the boom. Only minor injuries occurred despite the scale of equipment involved.
Root Cause Analysis
| Factor | Details |
| Unexpected Soil Settlement | The crane struck a soft subsurface zone, causing rapid sinkage and dynamic load transfer. |
| Boom Overload | Sudden hammer drop induced bending stress beyond boom capacity, leading to structural failure. |
| Inadequate Ground Verification | Lack of full geotechnical site characterization or real-time monitoring under heavy equipment zones. |
Impacts Due to the Issue, Problem, or Challenge
• Crane collapse interrupted piling operations.
• Minor injuries to personnel, but significant equipment damage.
• Raised questions about heavy-equipment use near public traffic areas.
Corrective Actions Taken
- Enhanced soil probes and site investigations before heavy-equipment deployment.
- Reinforced crane matting and support platforms to distribute loads over soft soils.
- Updated equipment protocols and emergency response drills for heavy-lift operations near live traffic.
Lessons Learned
• Heavy lifting operations demand rigorous soil support assessment—even when prior work has been routine.
• Dynamic events (e.g. hammer drops) can generate unanticipated stresses in equipment.
• Incorporating redundancy and ground-control contingencies can mitigate major failure risk.
Audit & Prevention: Project Control Questions to Ask on Future Projects to Help Control the Situation for Future Projects
Site Verification
- Has comprehensive soil stratigraphy been assessed near heavy-equipment staging areas?
- Are dynamic load effects included in soil-support planning?
Equipment Platform Integrity
- Are crane mats designed to distribute loads even under loss-of-support events?
- Are emergency procedures in place for suspected soil migration or equipment instability?
Construction Risk Mitigation
- Are lift planners and Geotech collaborating on hazardous-load zones?
- Are inspection protocols verifying platform integrity at each operation day’s start?