Update: This article was updated with the latest death toll.
A brand-new pedestrian bridge in Miami collapsed this afternoon (March 15), killing at least four people and injuring at least nine others, authorities say.
The main walkway of the $14.2-million bridge was installed just five days before the collapse, on March 10, designed to eventually offer students at Florida International University safe passage over a busy highway and into Sweetwater, a small suburban neighborhood.
Exactly what caused the collapse was not immediately clear, as emergency responders assess the situation and continue to search for survivors under the rubble. Several cars were crushed beneath the structure, according to local media reports.
Called an “instant bridge,” the 950-ton walkway was lowered into place by cranes, a process that took several hours. Expected to open sometime in 2019, it was the architectural product of a collaboration between MCM Construction and FIGG Bridge Design, which was responsible for the massive Sunshine Skyway Bridge further over Tampa Bay.
Most bridges collapse not because of an engineering failure, but because the structures can’t withstand natural forces such as unusually high winds or earthquakes. In America, specifically, concerns over aging infrastructure have sparked more recent conversations around the stability and reliability of bridges.
The American Society of Civil Engineers have given the more than 614,300 American bridges a C+ rating, saying that one in nine are considered structurally deficient. Most of that has to do with weaknesses that arise because of age, and a total update of the system is estimated to cost about $123 billion. The average age of a bridge in the US is about 42 years. On average, Americans make 188 million trips across structurally deficient bridges every day.
The incident in Florida had nothing to do with age. While the project was still unfinished, authorities will be investigating what engineering failure might have contributed to the collapse.