In the article, “I-5
and the Physics of Bridge Collapse,” Hartsfield (2013) has stated that most
bridges including the I-5 bridge failed due to inevitable design flaws. The
author implies the possibilities that can cause a bridge to collapse including
construction errors or miscalculations for cantilever, and high external force
for suspension bridges. According to Hartsfield (2013), “A truss bridge holds
as long as the beams themselves don’t break and the joints stay together.” In
this regard, a truss bridge can collapse once a part of the structural beam
fails. He further states that the unfortunate tragedy of the I-5 truss bridge
might have been due to the impact caused by a truck, as it crashed into one of
the beams. Hartsfield also mentions that nevertheless, it is critical to
understand the underlying problem to determine the actual cause of unpredicted
collapse in bridges.
While truck collision contributed to the
collapse of I-5 truss bridge, four main negligence factor had played the key role to this catastrophe. First of all, Washington State Department of
Transportation(WSDOT) should have ensure that every permit given out has oblige
to the minimum vertical height clearance level. As WSDOT is responsible of acknowledging
the proposed routes for company’s oversized vehicles; they should have checked
that all registered vehicles are suitable to utilise the I-5 bridge before
granting permission. According to a website from National Transportation Safety
Board(NTSB), companies were not prompt to perform route surveys since WSDOT did
not technically review permits.
Another significant reason would be the design
flaws of the I-5 truss bridge. According to an article, Ouellette (2016), “The
key issue in this case is the variable vertical bridge clearance.” The I-5
bridge is constructed with a curve top, whereby the vertical height varies throughout
the different lanes; the lanes nearer to the middle of the bridge is built
higher than the lanes nearer to the river. Therefore, when the truck driver
drove under the lower height lane to give space to another vehicle, it collided
with the structural beam by two inches.
The drivers who are involved has conduced to
the I-5 bridge failure. The pilot car driver should have taken more responsibilities
in her duty of escorting the truck safely. According to the NTSB website, the pilot
driver has admitted to making a conversation with her husband on the phone when
passing through the I-5 bridge. It is also reported that the antenna of the pilot
car was not straight which did not allow accurate measurements of the vertical
height. The pilot driver is either too distracted to notice the warnings or the
measuring system of the pilot car did not operate effectively due to the misaligned
antenna.
The truck driver should have followed the pilot
car at a further distance. According to Ouellette (2016), “The driver was
following the pilot car too closely.” The truck driver did not tail at a recommended
distance, so even if the pilot driver did warn the truck driver about the vertical
clearance height, the truck driver would not have an ample responsive time to avoid
the collision.
Lastly, lack of attention to sustain the
bridge is another notable factor for this disaster. According to NTSB, the data
on bridge strike of the I-5 bridge is not diligently recorded, as well as the
data for navigation system is not updated. Preventive measures could be set up to
reduce the risk of the bridge failing, and have oversized vehicle drivers to be
warned on the danger if these documents were managed attentively.
Human error in ergonomics is unavoidable. The
new design of I-5 bridge should be reinforced to ensure that the height
clearance level is same throughout the lanes. WDSOT should practice reviewing proposed
route of all oversized vehicles strictly, and provide mandatory training for
both truck and pilot drivers. A standardize database can be established for all
transportation company to follow. At the end of the day, everyone needs to play their role solemnly to avert
similar tragedy from happening.
Reference:
Tom.H (2013, May 28).
I-5 and the physics of bridge collapse. RealClear Science.com. Retrieved from https://www.realclearscience.com/articles/2013/05/29/i-5_and_the_physics_of_bridge_collapses_106544.html
National
Transportation Safety Board. (2014). Washington State I-5 Bridge Collapse Abstract. Retrieved
July 15, 2011 from https://www.ntsb.gov/news/events/Pages/2014_I5_Bridge_BMG-Abstract.aspx
Jennifer.O
(2016, August 16). New analysis confirms why the skagit river bridge collapsed.
GIZMODO. Retrieved from https://gizmodo.com/new-analysis-confirms-why-the-skagit-river-bridge-colla-1785842162
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