Skip Ribbon Commands
Skip to main content
Safety Recommendation Details

Safety Recommendation H-84-049
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: CONDUCT DETAILED INSPECTIONS OF THE MIANUS RIVER BRIDGE AND OTHER REPRESENTATIVE BRIDGES HAVING A SKEWED AND NONSKEWED SUSPENDED SPAN DESIGN WITH PIN AND HANGER ASSEMBLIES TO DETERMINE WHETHER THERE IS A SIGNIFICANT DIFFERENCE BETWEEN THE TWO DESIGNS IN TERMS OF THE MOVEMENT OF HANGERS ON PINS DUE TO EITHER DEAD OR LIVE LOADING AND WHETHER SUCH MOVEMENT IS ACCEPTABLE.
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: 3/19/1987
Addressee(s) and Addressee Status: FHWA (Closed - Acceptable Action)
Keyword(s):

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

From: FHWA
To: NTSB
Date: 11/7/1986
Response: SEVERAL RECENTLY COMPLETED AND ONGOING STUDIES INCLUDING THOSE BY CONSULTANTS TO CONNECTICUT AND THE NTSB PERTAINING TO THE MIANUS RIVER BRIDGE PROVIDE SUFFICIENT INFORMATION TO INFORM BRIDGE OWNERS THAT SUCH BRIDGES SHOULD BE INSPECTED FREQUENTLY. IN FACT, ALL BRIDGE OWNERS THAT WE ARE AWARE OF HAVE INITIATED STEPS TO RETROFIT OR REPLACE FRACTURE CRITICAL PIN AND HANGER SUSPENDED SPAN BRIDGES HAVING SIGNIFICANT SKEW ANGLES.

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

From: FHWA
To: NTSB
Date: 11/9/1984
Response: FHWA LTR: DISCUSSIONS ARE UNDERWAY WITH RESEARCHERS TO EVALUATE THE FEASIBILITY OF THE RECOMMENDED STUDY.