Good, your, time of the day to you, this video marks the 200th episode of in its many iterations
of Plainly difficult, it’s taken 6 years over 750,000 subscribers to get here and I’m
still surprised that you all keep on coming back every week to hear me talk and watch
my dodgey cartoons.
But I’m glad you do!
Whilst I’ve got your attention, would you want me to revive one of my early day’s
series in the future, such as strange places or interesting people.
If so, what would you like me to cover?
Let me know in the comments.
Anyway that’s enough of me talking time for the episode of me well, talking….
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It is a december morning, and traffic is flowing along the Interstate 75 in McMinn County,
Tennessee, United States.
All is calm until two lorry’s crash, both drivers are Uninjured and in the face of it
this seems like a pretty unremarkable event, however it would set off one of the USAs most
deadly pileups in living memory.
Hello my name is John and welcome to plainly difficult and today’s video on the I-75
disaster.
Background
The I-75 is one hell of a long road, stretching from Florida’s Miami lakes all the way to
the Canadian border, measuring in at 1787 miles this behemoth highway slices through
6 us states.
The first parts of the route had been opened to the public in 1957, and over the following
decades sections would be added; the section that will be the focus of today’s video
is a part of 4 lane highway opened in december 1973.
More specifically the SR163 interchange, near Calhoun Tennessee, this section of road is
situated between two valleys and is very susceptible to quick-forming fog.
In the area there are severel locations In which water collects such as behind the Chickamauga
Dam and in the settling ponds of a local paper mill, operated by now defunct bowater inc.
This alarmingly quick and thick fog was responsible for 6 multi vehicle collisions in which several
people had lost their lives.
With a now increasingly notoriously bad stretch of road in the state the Tennessee Department
of Transportation (TDOT) decided to try and improve the situation.
What they did was to install dual warning signs the following year which read "Extreme
Dense Fog Area Next 5 Miles" along this stretch in each direction, which contained flashing
lights that would activate if fog was detected.
In addition state troopers would be placed along the section on foggy days to help reduce
the speed of motorists.
The initial spate of the section of roads pileups came to an end in 1979, This accident
involved 18 vehicles, and resulted in 3 deaths and 14 injuries.
And all would be quiet for over 10 years until two trucks had a minor crash.
The disaster
It is 0530 in the morning on the 11th December 1990, and a Tennessee state highway trooper
is conducting a pretty standard fog check.
He found that the morning, as far as he could see, was acceptable on the visibility scale
(show scale), a light fog would descend on the road, and was noted by an off duty highway
patrol captain, although it was not causing visibility issues.
The fog would continue to intensify as the morning dragged towards 9am, witnesses would
later report the thickest accumulating at the state route overpass 163 near Calhoun.
The distance that drivers could see varied between 20-10 feet, but some even reported
less.
Because of the visibility issues many drivers slowed down however some did not, this is
when at roughly 0910 am a freightliner lorry was struck in the rear by another lorry Which
had a tanker trailer, the former was traveling at 25mph and the latter 45mph.
The accident was pretty trivial, both drivers of the south bound trucks were uninjured,
they stopped to inspect the damage roughly 100ft south past the overpass.
After a few minutes of pleasantries and checking out the damage a 1991 Oldsmobile saloon vehicle
struck the rear of the tanker, which itself was then struck by a truck.
This caused the car to crush between the two trucks and cause a fire which killed both
driver and passenger of the Oldsmobile.
A secondary cluster of crashes occurred a little bit back north on the southbound lanes,
this involved 72 vehicles.
Around the same time vehicles on the northbound started to slow which were then themselves
crashed into, by 0920 there were two sets of pileups one in each direction, some of
the collisions caused further fires, which burned victims vehicles and even melted the
asphalt road surface.
Some were burnt Beyond recognition, just 4 minutes after the Initial collision 911 had
recived its first calls.
First responders were quick to arrive on the scene, by 0930 a triage had been set up for
the wounded on the northern side of the highway, the overpass was repurposed as a helicopter
landing site for the most seriously injured, many others were sent via ambulance to local
medical centres.
More than 200 rescue personnel were involved in rescue and recovery work on the highway.
In total 99 vehicles were involved in the pileups, 12 would die with a further 42 injured.
The accident site also posed a hazardous materials risk due to the number of freight vehicles
involved, this would require specialist clean up work.
The NTSB attended the scene pretty quickly to begin investigating the underlying cause
of the horrific number of crashes.
The investigation
investigators had quite a large number of witnesses to interview as nearly 100 vehicles
were involved, because of this the ntsb would take the best part of 2 years to release its
findings.
Initially the finger of blame was pointed at the bowater paper mill and its settling
ponds, but the ntsb couldn’t find definitive proof.
The striking quickness of the onset of the fog, was one of the most startling parts of
the story, one eye witness who was under the overpass stated they could not see the bridge
just a few feet above their head.
The NTSB put the root cause of the accidents down to “drivers responding to the sudden
loss of visibility by operating their vehicles at significantly varying speeds".
But even though the NTSB didn't put the blame on bowater for the fog the US department of
energy had contradicted this finding 9 years before the accident, when it concluded the
plant was likely to cause 3 times more fog than what would naturally occur.
As such multiple lawsuits were aimed at Bowater, which would result In an out-of-court settlement
of $10 million with 44 victims and family members of victims in January 1994.
But it wasn't all bowaters fault, the state had failed to implement proper fog detection
procedures, and as such it spent 4.5 million on a computerised fog detection system.
This is a pretty sophisticated system with nine forward scatter visibility sensors, 14
microwave radar vehicle detectors, and 21 closed-circuit television (CCTV) cameras.
Which is linked to variable speed limits, flashing lights and warning signs.
The variable speed limit lowers from 70 to 50 miles per hour (113 to 80 km/h) at visibility
below 1⁄4 mile (0.40 km), and to 35 miles per hour (56 km/h) when the visibility is
below 480 feet (150 m).
Access to the highway in the area is restricted by gates when the visibility drops below 240ft.
The pileup highlights the risks of travelling in poor visibility.
And serves as a sobering reminder that an average commute can become deadly.
Well thank you very much for watching this 200 episode of playing a difficult hopefully
you will have well over 200 more I’m going to have a nice vanilla latte to celebrate
and I’ll see you all next week.
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Plainly difficult videos are produced by me John, in a wet and windy suburban Southeast
corner of London, uk.
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https://www.ntsb.gov/investigations/AccidentReports/Reports/HAR9202.pdf