NTSB. The additional examina-
tions and forensic deconstruction
of these components will occur
there. • The investigative team has con-
firmed that workers were adjust-
ing tension on the two tensioning
rods located in the diagonal mem-
ber at the north end of the span
when the bridge collapsed. They
had done this same work earlier at
the south end, moved to the north
side, and had adjusted one rod.
They were working on the second
rod when the span failed and col-
lapsed. The roadway was not
closed while this work was being
performed. NTSB says ongoing work includes:
• Removal of the post-tensioning
device to a temporary storage
area and preparing it for ship-
ment; • Preliminary comparison of bridge
schematics to measurements ob-
tained during the investigators’ ex-
amination of the collapsed
structure; and
• Interviews with first responders.
The NTSB said that “while seg-
ments of the bridge are being trans-
ported to and stored at an FDOT
facility, there are no plans to recon-
struct the bridge as part of the NTSB
investigation into why the bridge col-
lapsed. The nature of the structure
and the way it failed make recon-
struction impractical.”
There have been unofficial specu-
lations about whether the design
was properly evaluated before con-
struction began, and whether the
contractor had received briefings on
how to safely build the structure.
“Outside expert speculation has
moved beyond just potential con-
struction error to focus increasingly
on possible design flaws that might
have made the bridge structurally
vulnerable,” the Miami Herald re-
ported. “I would say they were pushing
the envelope,” Nel Hawkins, an
emeritus engineering professor at
the University of Illinois who special-
izes in concrete construction was
quoted as saying. “The question is,
to what extent had the new concepts
in this been validated through testing
prior to actually putting it in place?”
The Herald reported that the “ad-
mittedly speculative consensus has
coalesced around a view of the FIU
project as a novel design with a high
‘wow’ factor, but also hidden struc-
tural risks and vulnerabilities that
were probably compounded by a
last-minute design change, all
brought to a catastrophic conclusion
by engineering and construction mis-
calculations.” But it will likely be many months –
perhaps years – with presumably ex-
tensive litigation – before the story
can truly come to a definitive conclu-
sion. The story touches close to the
heart of FIU, with nationally recog-
nized programs in engineering and
construction management.
The university’s Moss School of
Construction, Infrastructure and Sus-
tainability attracts students from
across the U.S. and internationally
with its programs.
The school is “the preeminent
center for advancement and dissemi-
nation of construction knowledge,”
director Irtishad Ahmad says on the
FIU website. “Our undergraduate stu-
dents get hands on training and high
class instructions in all areas of con-
struction. Graduate students take
courses in advanced topics in con-
struction and get involved in re-
search with the faculty members.
Both groups enjoy excellent employ-
ment opportunities by being in South
Florida – one of the busiest geo-
graphic regions in construction in the
country.” Florida Construction News — SPRING 2018 – 5