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Safety Recommendation Details

Safety Recommendation H-84-052
Details
Synopsis: ON JUNE 28, 1983, A 100-FOOT-LONG SUSPENDED SPAN BETWEEN PIERS 20 AND 21 OF THE EASTBOUND TRAFFIC LANES OF THE INTERSTATE ROUTE 95 HIGHWAY BRIDGE OVER THE MIANUS RIVER IN GREENWICH, CONNECTICUT, COLLAPSED AND FELL 70 FEET INTO THE RIVER BELOW. TWO TRACTOR-SEMITRAILERS AND TWO AUTOMOBILES PLUNGED INTO THE VOID IN THE BRIDGE AND WERE DESTROYED BY IMPACT FROM THE FALL. THREE VEHICLE OCCUPANTS DIED, AND THE OTHER THREE RECEIVED SERIOUS INJURIES. THE NATIONAL TRANSPORTATION SAFETY BOARD DETERMINED THAT THE PROBABLE CAUSE OF THE COLLAPSE OF THE MIANUS RIVER BRIDGE SPAN WAS THE UNDETECTED LATERAL DISPLACEMENT OF THE HANGERS OF THE PIN AND HANGER SUSPENSION ASSEMBLY IN THE SOUTHEAST CORNER OF THE SPAN BY CORROSION-INDUCED FORCES DUE TO DEFICIENCIES IN THE STATE OF CONNECTICUT'S BRIDGE SAFETY INSPECTION AND BRIDGE MAINTENANCE PROGRAM.
Recommendation: THE NTSB RECOMMENDS THAT THE FEDERAL HIGHWAY ADMINISTRATION: PRESCRIBE AN OBJECTIVE STANDARD FOR REPAIR OR REPLACEMENT OF PIN AND HANGER ASSEMBLIES ACCORDING TO MEASURED CONDITIONS OF MISALIGNMENT, DISTORTION, OR CHANGES IN THE POSITION OF ELEMENTS OF THE ASSEMBLY.
Original recommendation transmittal letter: PDF
Overall Status: Closed - Acceptable Alternate Action
Mode: Highway
Location: Mianus River, Greenwich, CT, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA83AH003
Accident Reports: Collapse of a Suspended Span of Inter- state Route 95 Highway Bridge over the Mianus River
Report #: HAR-84-03
Accident Date: 6/28/1983
Issue Date: 7/19/1984
Date Closed: 3/19/1987
Addressee(s) and Addressee Status: FHWA (Closed - Acceptable Alternate Action)
Keyword(s):

Safety Recommendation History
From: NTSB
To: FHWA
Date: 3/19/1987
Response:

From: FHWA
To: NTSB
Date: 11/7/1986
Response: IN PREPARING THE NEW MANUAL, "INSPECTION OF FRACTURE CRITICAL BRIDGE MEMBERS," IT WAS DETERMINED THAT PREPARING REPAIR OR REPLACEMENT STANDARDS FOR PIN AND HANGER ASSEMBLIES WAS INAPPROPRIATE FOR AN INSPECTION MANUAL. INSTEAD, THE INSPECTOR WILL BE DIRECTED TO NOTIFY HIS SUPERVISOR OF MISALIGNMENT, DISTORTION, OR CHANGES IN THE POSITION OF ELEMENTS OF THE PIN AND HANGER ASSEMBLY.

From: NTSB
To: FHWA
Date: 6/10/1985
Response:

From: FHWA
To: NTSB
Date: 11/9/1984
Response: FHWA LTR: TO THE DEGREE CURRENTLY POSSIBLE, THIS WILL BE INCLUDED IN THE NEW MANUAL, "INSPECTION OF FRACTURE CRITICAL BRIDGE MEMBERS," NOW UNDER DEVELOPMENT. BECAUSE THE ADVERSE EFFECTS OF MISALIGNMENT OR DISTORTION OF INDIVIDUAL ASSEMBLIES DEPENDS UPON THE UNIQUE CHARACTERISTICS OF EACH BRIDGE, IT MAY NOT BE POSSIBLE TO DEVELOP GENERALIZED STANDARDS. INSTEAD, EACH BRIDGE OWNER MAY HAVE TO DEVELOP INDIVIDUALIZED CRITERIA FOR EACH BRIDGE CONTAINING FRACTURE CRITICAL PIN AND HANGER SUSPENDED SPAN DETAILS.