I-95 Mianus River Bridge Collapse in 1983

On Tuesday, June 28, 1983 at 1:30 am a 100 foot section of the I-95 Mianus River Bridge collapsed due to a structural failure. Three people were killed, and three were seriously injured as two trucks and three cars plunged 70 feet into the river that was almost at high tide. Had the event occurred during the day, the tragedy would have been far worse.

For about a month afterwards, the Northbound lanes of I-95 were detoured onto Route One in Cos Cob (Greenwich), when a temporary truss allowed cars and light trucks to traverse the gap. Busses and heavy trucks continued to use Route 1 for another two months until a stronger truss could be put in place. 80,000 to 90,000 cars per day traversed the bridge prior to the collapse. For an entire summer, they had to squeeze through Greenwich on Route One.

Almost a mile long, the bridge used a cantilevered pin and hanger design which was popular in the 1950’s, but is no longer used in US highway construction. There was considerable shock that at only 25-years-old, the relatively new bridge could suffer such a failure. Much of its failure can be attributed to poor maintenance and ineffective inspections by the CT Department of Transportation. The bridge had been inspected just 9 months before the disaster, but the corrosion that caused the failure of one of the pins wasn’t uncovered.

Corrosion of the pin and hanger assemblies that held the cantilevered sections together was the reason for the structural failure. The missing hanger pin was found in the river below after the collapse. Some of the drains on the roadway had been paved over 10 years prior, which dramatically increased corrosion in the pins and hangers. There is also an unsubstantiated rumor that “sludge runners”- trucks carrying toxic wastes – would deliberately spill some of their load as they passed over the Mianus River, leading to unanticipated causes of corrosion.

In the weeks leading up to June 28, nearby residents had complained to local authorities about unusual noises coming from the bridge, but no investigation of these complaints was made.

The bridge was completely replaced in 1992.