Florida bridge in fatal collapse was touted as an engineering marvel
UPDATE: As of Friday morning, police say at least six people are dead after the Florida bridge collapsed.
The FIU-Sweetwater UniversityCity Bridge was supposed to be an engineering marvel.
Five days before the bridge collapsed onto a busy eight-lane road, crushing several vehicles and killing at least four people, Florida International University (FIU) issued a press release trumpeting the cutting-edge techniques used to install the 95-ton pedestrian walkway.
“On March 10, the main span of the FIU-Sweetwater UniversityCity Bridge was lifted from its temporary supports, rotated 90 degrees across an eight-lane thoroughfare, and lowered into its permanent position,” read the release, which was accompanied by tweets featuring video of the procedure.
The bridge was built using revolutionary construction methods that allowed for efficient installation, FIU said, while minimizing traffic disruptions and reducing risks to pedestrians and commuters.
Here’s a look at some of the cutting-edge construction methods that prompted FIU to label the bridge the “first of its kind,” before Thursday’s tragic collapse.
Accelerated Bridge Construction
The FIU press release stated the bridge was being built using Accelerated Bridge Construction (ABC) techniques.
ABC is bridge construction that, unlike conventional construction, significantly reduces the amount of on-site construction time, which can be time-consuming and weather-dependent, not to mention disruptive to traffic, according to the Federal Highway Administration’s ABC manual.
WATCH: Multiple casualties after pedestrian bridge collapses in Miami
One of the best strategies to achieve this is through the use of prefabrication, wherein certain components are built offsite before being installed in place.
When prefabricated bridge elements and systems “are built off the critical path and under controlled environmental conditions, improvements in safety, quality and long-term durability can be better achieved,” according to the Federal Highway Administration.
Self-Propelled Modular Transportation
Once structural components are prefabricated offsite, they need to be transported to the main site and installed in place.
This is done using Self-Propelled Modular Transporters (SPMTs), gigantic platform vehicles that can lift, transport and set heavy loads in place.
“SPMTs are motorized vehicles that move at walking speed and are capable of carrying large structures, such as bridges, from offsite locations, positioning them precisely into final position,” according to the Federal Highway Administration. “The SPMT then exits the site, opening the area to traffic possibly within minutes or certainly within a few hours.”
WATCH: Cars seen under Florida bridge after collapse as emergency officials respond
In the case of the FIU bridge, the 175-foot main span was first constructed atop temporary supports, according to an FIU info sheet on the project. SPMTs were then moved under the main span, and lifted it before moving it along an arc-shaped path and lowering it into place.
It was the largest pedestrian bridge moved via SPMT in U.S. history, according to FIU’s release.
‘This is magic’
“This project is an outstanding example of the ABC method,” said Atorod Azizinamini, chair of FIU’s civil and environmental engineering department, according to FIU. “Building the major element of the bridge – its main span superstructure – outside of the travelled way and away from busy Eighth Street is a milestone.”
Several FIU engineering and architecture students watched the installation of the superstructure at 5 a.m.
“I would say this is magic. In five hours using that ABC technology and sensors, the bridge is already there,” said one civil engineering doctoral student said, according to FIU’s release.
“In the classroom, we learn about the design, the construction, the safety – that’s a big issue – and here we’re seeing it actually happening.”
WATCH: Reporter describes chaotic scene at Florida International University following bridge collapse
Construction techniques aside, the bridge also boasted other noteworthy elements including a Category 5 hurricane-proof structure and self-cleaning concrete treated with pollutant-trapping titanium dioxide.
After the collapse, FIU president Mark Rosenberg released a statement saying he was “heartbroken” at the news.
“We are working with the appropriate agencies to assist in rescue efforts,” he added.
It’s unclear what exactly led to the collapse. The National Transportation Safety Board says it is investigating.
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