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Safety Recommendation Details

Safety Recommendation H-84-057
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 AMERICAN INSTITUTE OF STEEL CONSTRUCTION: REVIEW THE PIN CAP DETAIL SHOWN IN THE AISC MANUAL OF STEEL CONSTRUCTION TO DETERMINE IF IT SHOULD BE DELETED FROM THE MANUAL OR IF QUALIFYING CONDITIONS SHOULD BE ATTACHED TO ITS USE.
Original recommendation transmittal letter: PDF
Overall Status: Closed - Acceptable 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: 7/11/1989
Addressee(s) and Addressee Status: American Institute of Steel Construction (Closed - Acceptable Action)
Keyword(s):

Safety Recommendation History
From: NTSB
To: American Institute of Steel Construction
Date: 7/11/1989
Response:

From: American Institute of Steel Construction
To: NTSB
Date: 5/5/1989
Response: THE PIN CAP USED IN THE MIANUS RIVER BRIDGE DIFFERED SIGNIFICANTLY FROM THAT SHOWN BY AISC: THE MIANUS PIN CAP HAD A THICKNESS OF 5/16 INCH, WHEREAS THE AISC DETAIL SHOWS A THICKNESS OF 3/4 INCH. THIS DIFFERENCE HAS A MAJOR EFFECT ON THE STRUCTURAL BEHAVIOR WHEN THE CAP IS SUBJECTED TO LATERLA FORCES. SUCH OUT-OF-PLANE FORCES CAN OCCUR AS A RESULT OF THE SKEW OF THE BRIDGE AND OTHER GEOMETRIC EFFECTS, OR THE BUILD-UP OF CORROSION PRODUCTS. THE SECOND POINT RAISED BY REC. H-84-57 RELATES TO THE POSSIBILITY THAT CORROSION MAY OCCUR, WHICH WOULD BE HIDDEN FROM VIEW BY THE KEEPER PLATE.

From: NTSB
To: American Institute of Steel Construction
Date: 12/21/1988
Response: