6 people were killed and at least nine injured when a foot bridge under construction at Miami's Florida International University collapsed on a busy eight-lane street on Thursday.
The 950 ton, 175-foot span foot bridge fell onto the roadway crushing cars that were waiting at a red light at 8th Street and 109th Avenue.
The bridge was built on the side of the roadway using FIU's "Accelerated Bridge Construction (ABC) technology". The construction contract was awarded to a minority contractor based in Miami.
The bridge would have connected FIU University to Miami's Sweetwater neighborhood, allowing students and faculty to cross safely over the busy street, where an 18-year-old FIU student was struck by a car and killed last year.
"It is exactly the opposite of what we had intended, and we want to express our deepest condolences to the family and loved ones of those who have been affected," said FIU President Mark Rosenberg in a video.
Construction crews took just 7 hours to hoist the bridge span into place over the road on Saturday.
The bridge was designed to be supported from above by a system of thick steel cables (see illustration) and a reinforced concrete center support column. But the cables had not been installed yet.
On March 13, FIU president Rosenberg tweeted this photo of the bridge sitting on red construction equipment by the side of the road. That equipment was removed when the bridge was swung into place over the road with no cables to hold it up.
In theory, the bridge span should have supported its own weight until the cables were installed. But in reality, a bridge without center support will buckle under its own weight and collapse.
A monitoring company responded to criticism from Twitter users after deleting the above tweet on Thursday.
BDI Test released a statement confirming it was hired by the crane company to monitor the stress on the bridge after it was hoisted into place on Saturday. The company wrapped up its work nearly a week before the walkway collapsed.
"BDI was contracted to conduct monitoring while the bridge was moved into place," the company stressed in a post on its website Thursday. "BDI was not involved in the bridge’s design or construction and no BDI personnel or equipment were onsite at the time of the incident."
The foot bridge was scheduled to open for pedestrians and cyclists in 2019.
The deadliest fail of a suspension or cable stayed walkway in the U.S. occurred on July 17, 1981 at the Hyatt Regency in Kansas City, Missouri.
2 walkways, one directly above the other, collapsed onto a tea dance party in the hotel lobby, killing 114 people and injuring 216.
The official cause of the deadly Kansas City walkway collapse was "Structural overload resulting from design flaws." All engineers involved in the design and construction of the Hyatt Regency walkways lost their engineering licenses.