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Safety Recommendation Details

Safety Recommendation H-84-055
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 ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS: MODIFY ARTICLE 1.7.27 OF THE "STANDARD SPECIFICATIONS FOR HIGHWAY BRIDGES" (1977) AND SUCCEEDING "INTERIM SPECIFICATIONS" TO DESCRIBE FORCES WHICH MIGHT RESULT IN LATERAL MOVEMENTS OF MEMBERS ON PINS TO BE CONSIDERED IN DESIGNING PINNED ASSEMBLIES.
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: 6/20/1995
Addressee(s) and Addressee Status: American Association of State Highway and Transportation Officials (Closed - Acceptable Action)
Keyword(s):

Safety Recommendation History
From: NTSB
To: American Association of State Highway and Transportation Officials
Date: 6/20/1995
Response: THE BOARD NOTES THAT THE STANDARD SPECIFICATIONS FOR HIGHWAY BRIDGES--15TH EDITION TOGETHER WITH THE INTERIM SEPCIFICATONS-1993 & 1994, CONSIDER LATERAL FORCES IN DESIGN SPECIFICATIONS. SINCE THE DESIGN OF PINNED ASSEMBLIES IS DISCUSSED IN SECTION 10, "INKS & HANGERS," OF THE STANDARD SPECIFICATIONS FOR HIGHWAY BRIDGES 15--TH EDITION, H-84-55 HAS BEEN CLASSIFIED "CLOSED--ACCEPTABLE ACTION."

From: American Association of State Highway and Transportation Officials
To: NTSB
Date: 12/8/1994
Response: I BELIEVE EARLIER LANGUAGE ON THIS SUBJECT IN STANDARD SPECIFICATIONS HAS BEEN STRENGTHENED SINCE 1985 & FOR YOUR INFO, I AM ENCLOSING THE 15TH EDITION OF STANDARD SPECIFICATIONS TOGETHER WITH THE INTERIMS FOR 1993 & 1994.

From: NTSB
To: American Association of State Highway and Transportation Officials
Date: 3/25/1986
Response:

From: American Association of State Highway and Transportation Officials
To: NTSB
Date: 2/13/1986
Response: MR. CASSANO HAS ASKED THE TECHNICAL COMMITTEE FOR LOADS AND LOAD DISTRIBUTION TO GIVE THE ISSUE OF SKEW INDUCED LOADS FURTHER CONSIDERATION. THE TECHNICAL COMMITTEE WILL HAVE A CHANGE IN LANGUAGE RESPONSIVE TO NTSB'S CONCERNS PREPARED FOR CONSIDERATION BY THE STATE BRIDGE ENGINEERS AT THE SPRING REGIONAL MEETINGS OF THE SUBCOMMITTEE ON BRIDGES AND STRUCTURES.

From: NTSB
To: American Association of State Highway and Transportation Officials
Date: 1/14/1986
Response:

From: American Association of State Highway and Transportation Officials
To: NTSB
Date: 9/11/1985
Response: THE PRESENT AASHTO SPECIFICATIONS REQUIRE THAT MEMBERS BE DESIGNED TO RESIST LATERAL LOADS. THESE LOADS ARE GENERATED IN MANY WAYS, E.G. WIND, TORSION, SEISMIC LOADS AND SKEW EFFECTS, ALL OF WHICH SHOULD BE CONSIDERED IN DESIGN. CORROSION SHOULD BE MINIMIZED THROUGH THE USE OF GOOD DETAILS, PROPER PAINTING, FREQUENT INSPECTION AND REPAIR, AND THE USE OF PROPER MATERIALS.