A freshman student of Florida International University was killed by a car while crossing a street near the main campus. To refrain from the same incident to happen again, one of the measures that FIU made was to build a pedestrian bridge – using an innovative construction method – connecting the bustling Miami college with the city of Sweetwater.
But as the construction of the pedestrian bridge was going on, notably reported to be safe throughout and still on schedule for completion in early 2019, the structure collapsed in the afternoon of March 15 taking the lives of six people. At least as of March 18.
Reports revealed by Sen. Marco Rubio say that the tragedy happened while the cables that suspend the pedestrian bridge were being tightened after they have gotten loose.
National Transportation Safety Board’s chairman Robert Sumwalt, with information relayed to them, said that construction workers were on the bridge at the time of the collapse.
However, the definite cause of the collapse is yet to be fully investigated by the NTSB, the Occupational Safety and Health Administration (OSHA) and the Federal Highway Administration (FHA), along with the police department. The focus now is to clear the area and get to the victims of the collapse while the investigation is underway.
“Our first priority is getting to those victims,” Juan Perez, director of the Miami-Dade Police Department, said Friday morning. He admitted that it is “a slow and painstaking process to break the debris into smaller pieces for removal” and to get to the vehicles that were crumpled when the bridge collapsed.
Meanwhile, Miami-Dade County Deputy Mayor Maurice Kemp said Friday, “Our primary focus is to remove all of the cars and all of the victims in a dignified manner and not compromise the investigation in the process. The investigation is vital because we want to ensure that this type of accident doesn’t happen again locally, or anywhere in this country.”
Video by Munilla Construction Management. Bridge With New Construction Method Collapse
What was supposed to be a landmark construction method ended in a collapse.
FIU, together with FIGG Engineering-Bridge Group as the bridge designer and MCM Construction as the general contractor, developed the Accelerated Bridge Construction (ABC) technology, which is said to be a quicker and more cost-effective process.
It involves building the main span of the bridge on temporary supports and transferring it to its final place. Known as Prefabricated Bridge Elements and Systems (PBES), this type of ABC technology enables contractors to make the bridge elements off-site and transport them to the end location for assembly. Moreover, a process called Self-Propelled Modular Transportation was performed – the FIU pedestrian bridge is the largest in U.S. history to be moved using this method.
Benefits of PBES include reduced traffic delays and road closures, safer work zones, less environmental impact, and generally more durable than those constructed using conventional method says the FHA.
Atorod Azizinamini, chair of FIU’s Civil & Environmental Engineering Department and director of the university’s Accelerated Bridge Construction University Transportation Center, was fully aware of these benefits and even boasted about the pedestrian bridge’s construction method on the day the main span was installed – but five days before the collapse happened.
“This project is an outstanding example of the ABC method,” said Azizinamini. “Building the major element of the bridge – its main span superstructure – outside of the traveled way and away from busy Eighth Street is a milestone.”
A fact sheet about the bridge posted on FIU’s website indicated that the 950-ton bridge, which main span is 40 feet wide and 174 feet long, costs $14.2 million to build and was funded as part of a $19.4 million grant from the U.S. Department of Transportation. It was supposed to last for more than 100 years and designed to withstand the strength of a Category 5 hurricane.
Regretfully, the collapse of the pedestrian bridge did not come without a warning.
Denney Pate, an engineer from the construction firm in charge, saw a crack on the north end of the span.
Reporting to an official at the Florida Department of Transportation two days before the structure crashed, he called, “Hey Tom, this is Denney Pate with FIGG bridge engineers. Calling to, uh, share with you some information about the FIU pedestrian bridge and some cracking that’s been observed on the north end of the span, the pylon end of that span we moved this weekend.
“Um, so, uh, we’ve taken a look at it and, uh, obviously some repairs or whatever will have to be done but from a safety perspective we don’t see that there’s any issue there so we’re not concerned about it from that perspective although obviously the cracking is not good and something’s going to have to be, ya know, done to repair that,” he added in the voicemail.
The voicemail was not opened until Friday, a day after the bridge collapsed, because the official was out on assignment.
After the tragedy, FIGG Bridge Engineers released a statement that it is “carefully examining the steps that our team has taken in the interest of our overarching concern for public safety.”
Moreover, it said that the “the evaluation was based on the best available information at that time,” referring to its engineer’s conclusion that safety was not an issue.
However, a meeting was attended by representatives from FIU, the Florida Department of Transportation, Munilla Construction Management and FIGG Bridge Engineers to discuss the structural integrity of the span just a few hours before the bridge collapsed. It lasted two hours.
“The FIGG engineer of record delivered a technical presentation regarding the crack and concluded that there were no safety concerns and the crack did not compromise the structural integrity of the bridge,” Florida International University officials said Saturday in a statement.
Robert Accetta of the National Transportation Safety Board said the crack “does not necessarily mean that it is unsafe.”
Unfortunately, in this case, it does.
The designers of the bridge have pledged that that they will “pursue answers to find out what factors led to this tragic situation.”
Sources: Washington Post | CNN 1 | 2
