November 30, 2025 • 17 mins
A perfectly ordinary Tuesday morning turned into a wall of white and the worst commute of many people’s lives. We dive into the 99-car pileup on I-75 near Calhoun, Tennessee—how a fog-prone valley, river-backed reservoirs, and nearby industrial ponds set the stage for sudden zero visibility, and how human reactions at different speeds amplified a single impact into a chain of catastrophe. It’s a forensic tour through weather, geography, and the split-second choices that define disaster.
We walk you through the minutes that mattered: the first semi slowing in the southbound lanes, the unseen trucks ahead, the Oldsmobile crushed and burning, and the eerie progression as drivers entered from clear air into chaos. Then the response: the first deputy stumbling past the wrecks to call in help, triage sites on the median, hazmat teams managing peroxide-fueled fires, and a multi-agency push that saved lives while the pileup grew. The human side meets hard logistics here—sirens in the fog, coordination across counties, and the grind of clearing a corridor that looked like physics gave up.
From there, we pull on the threads of accountability. The NTSB pointed to speed variance in sudden low visibility, but the report also flagged systemic failures: flimsy warning signs, no automated detection, no ramp controls. We revisit contested studies around Bowater’s settling ponds, a temperature inversion that day, and a settlement that acknowledged harm without conceding sole blame. Most importantly, we chart the fixes that finally worked: Tennessee’s $4.5 million fog detection system with visibility sensors, radar, CCTV, variable speed limits, and swing gates to lock down ramps when sight distance collapses. Since its launch—and a 2006 upgrade—this stretch hasn’t seen another fog-fueled mass crash.
If you’re drawn to transport safety, disaster history, traffic engineering, or just the anatomy of how small failures become big ones, this story delivers detail, context, and hard-earned lessons. Hit play, then tell us what you’d change first: driver behavior, industrial practices, or smarter infrastructure? Subscribe, share with a friend who loves history and engineering, and leave a review to help more curious listeners find the show.
Facebook: historyisadisaster
Instagram: historysadisaster
email: historysadisaster@gmail.com
Special thank you to Lunarfall Audio for producing and doing all the heavy lifting on audio editing since April 13, 2025, the Murder of Christopher Meyer episode https://lunarfallaudio.com/
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
SPEAKER_00 (00:01):
Tuesdays are great.
You made it past Monday, andyou're now one step closer to
the weekend.
But you still gotta get up waytoo early though.
Get dressed, hop in your car,and deal with traffic and
everyone else wondering why thehell they're up this early.
What could be better than that?
Well, maybe add in some fog.
(00:22):
Because fog always makeseverything better.
You're flying down the highway,then all of a sudden it's like
someone throws a blanket overyour windshield.
You can't see a damn thing, soyou slam into the idiot ahead of
you who decided to stop.
Don't worry though, you're notalone.
Because the guy flying up behindyou is about to tap that ass
(00:45):
too.
And really, is there a betterway to start today?
Just ask the commuters onInterstate 75 in Tennessee who
hit a sudden fog bank and foundthemselves involved in one of
the largest auto wrecks inhistory on Tuesday, December
11th, 1990.
So, what happened?
(01:05):
I'm Andrew, and this isHistory's A Disaster.
Tonight, we're driving into theI-75 fog disaster that resulted
in a 99-car pile-up just outsidethe small town of Calhoun,
(01:26):
Tennessee.
And tonight's episode is broughtto you by Polka Bob's Music
Center.
Polka Bob is currently running asurprise fire sale on accordions
and xylophones.
So come on down and say hi toPolka Bob.
You can squeeze his accordionand bang his xylophones before
deciding to take one home today.
(01:48):
Jeez, that's not creepy at all.
Why was he winking at me when hehanded me the ad to read?
I need better sponsors.
I-75, which runs from theCanadian border in Michigan all
the way down to Miami, Florida,is the second longest
north-south interstate afterI-95.
It runs through six differentstates for just under 1800
(02:13):
miles.
So, obviously, there's gonna besome shitty spots on the
highway.
And one of them just happens tobe outside Calhoun, Tennessee.
This 10 mile stretch of I-75lies 70 miles southeast of
Knoxville and runs from milemarker 29 to 39.
This stretch is in two separatevalleys surrounded by ridges
(02:36):
within the ridge and valleyAppalachians.
Appalachians.
The area has a lot of creeksthat run through these valleys
that flow into the HiawasseeRiver, a major river that cuts
the area in half near where theinterstate crosses.
The Chickamauga Dam, not fardownstream from the area,
(02:58):
creates a reservoir which backsup into this section of the
river, making large lakes nearthe interstate where these
creeks all meet up with theriver.
Also in the area is the BowWater Paper Mill.
The mill is just outside ofCalhoun, close to the interstate
and sitting on the banks of theriver.
At the time, Bow Water ownedland on both sides of the
(03:20):
interstate and operatedwastewater treatment settling
ponds next to it.
Now these settling ponds, and ifyou've ever driven past the
factory or a plant or anything,everyone's seen them, they're
the little lakes that sit outfront.
They're part of a large systemand it's used to help separate
solid pollutants fromwastewater.
Water flows into these ponds andthe heavy solid shit settles to
(03:44):
the bottom of the pond over timeand the cleaner water flows out.
It's part of a whole system, andthe system really has nothing to
do with the accident other thanthese ponds.
So, anyways, all that to sayit's a low-lying area with lots
of cold air and a ton of waterin the area.
Put all that together and yougot the perfect recipe for fog
(04:06):
soup.
Thick, nasty fog soup that canpop up in the area at any time
without warning.
If you live in the area orregularly drive through here,
like truck drivers, at somepoint you got caught in this
shit and have some kind of fogstory.
Since this section of Interstateopened up in 1973, there have
(04:26):
been multiple accidents here.
The first of which happened justwithin three months of the
opening and involved 18vehicles, three deaths, and 10
injuries.
And this was just the first ofmany.
So to help cut down on accidentsin the area, they put up a sign
which read Extreme Dense FogArea, next five miles, along the
(04:48):
stretch in both directions.
The sign contained flashinglights that would activate if
fog was detected.
So, yep, they put up a blinkylight on a sign that most people
aren't gonna pay attention toanyways.
Especially when the lightsflashed non-stop for three days,
like they did in the southboundlane prior to the accident, or
(05:09):
just didn't work at all like thenorthbound lanes.
And they put these signs upafter another 18 vehicle
accident occurred in 1979.
And since they put these signsup, there was no major accidents
at all throughout the 80s.
Although I highly suspect theyhad more to do with the
Tennessee Highway Patrol thanthe stupid blinky lights.
(05:33):
On foggy days, troopers wouldsit at the end of the foggy area
and well seeing a cop sitting,everyone's gonna slow down.
So there's that.
The Highway Patrol would also doroutine fog checks in the area.
Which brings us to December 11thof 1990.
During their early fog checks at5.30 and 8 o'clock, Highway
(05:55):
Patrol noted no fog in the area.
However, by 9 a.m.
the fog started rolling in.
Visibility was dropping as themiles ticked by and the fog grew
thicker, dropping from 20 feetto 10 to barely seeing past the
hood of your car.
At 9.10, a semi traveling in thesouthbound lanes carrying
(06:15):
daikumo peroxide in separatetanks slowed to 35 miles per
hour.
Unfortunately, the semi unseenin the fog ahead of them had
slowed to 25 and was rear-endedjust 100 feet south of the State
Route 163 overpass.
The truck drivers got out andattempted to check for damage
and bullshit for a few minutesbefore a 91 Oldsmobile sedan
(06:40):
smashed into the rear of thechemical semi.
Before anyone could move, theOldsmobile was crushed under the
semi and set on fire when it wasrear-ended by another semi.
Neither the driver or thepassenger of the Oldsmobile made
it out of the car.
This was the first, but far fromthe last cluster of accidents in
(07:01):
the southbound lanes.
At 9.15, the first accidenthappened in the northbound lanes
when an 87 Ford Escort slammedinto an 87 Honda near the
overpass, which in turn wasrear-ended by an 83 Toyota
pickup, which was then hit by a1990 Pontiac, which was then in
(07:22):
turn hit by an 89 Oldsmobile.
Surprisingly, no one was injuredin this mess.
As the minutes ticked by, thestopped commuters could hear the
sounds of impact, the screech ofbrakes, the crunching of metal
on metal, the secondaryexplosions as fuel tanks
ignited.
Some slowed or stopped to try tosee what was happening.
(07:42):
The stopped or slowed movingvehicles invisible in the fog,
waiting to be struck by driversstill traveling at a high rate
of speed.
Within minutes of the firstaccident, both directions of the
interstate had become a tanglednightmare of wreckage spanning
hundreds of yards.
Vehicles were crushed, stacked,thrown into positions that
(08:03):
seemed to defy physics.
Tractor trailers jackknifedacross multiple lanes.
Cars were smashed down tofractions of their original
size, wedged beneath largervehicles or sandwiched between
them, and still more vehicleskept coming.
Drivers emerged from clearconditions into fog with zero
warning, finding themselvessuddenly confronted with walls
(08:25):
of stop traffic and wreckage.
Even those who managed to breakcouldn't stop in time.
It was far too late.
The pile of wreckage just grewlarger.
Ten minutes after the firstcollision, the final accident
occurred.
Accidents in the southboundlanes involving 72 vehicles
(08:48):
would stretch for a fifth of amile north of the overpass.
The northbound lanes, a total of27 vehicles would be involved in
multiple accidents stretching aquarter mile south of the
overpass.
The first 911 calls startedcoming in as the first
northbound accident happened.
Within minutes, Bill Dyer of theBradley County Sheriff's Office
(09:10):
was on scene.
Being the first on scene, heoriginally completely missed the
first accidents in the fog.
He had to turn around and driveback to find the scene.
When he got back to the area, aseriously injured man stumbled
out of the fog and towards hiscruiser.
When he exited the cruiser tohelp the man, he could hear the
metal-on-metal sounds ofmultiple accidents just north of
(09:33):
his location.
As he got closer, the screams ofthe wounded got louder.
After seeing what he could ofthe devastation, he immediately
called for backup in emergencyservices.
Over 200 first responders wouldend up on site from as far away
as Chattanooga and Knoxville.
By 9.30, the Tennessee EmergencyManagement Agency began
(09:55):
coordinating the responsebetween the 33 different
departments who answered thecall for help.
Within minutes, the TennesseeHighway Patrol had the highway
shut down on both ends.
McMaine County EMS set up triagein the median north of the
overpass to evaluate the woundedas they were pulled from the
wreckage.
While Bradley County EMS set upanother triage site to the
(10:17):
south.
42 survivors were treated forinjuries ranging from minor cuts
and scrapes up to more traumaticinjuries that required
hospitalization.
The injured would be transportedto hospitals as far away as
Chattanooga and Knoxville.
In total, eight people died inthe fires raging across the
wreckage, and four more had diedas a result of injuries
(10:39):
sustained in the crash.
Firefighters from multipledepartments worked the fires
that had spread throughout thearea.
Most concerning was the presenceof chemical tanks containing
peroxides that were sendingflames 30 feet in the air.
Special hazmat teams had to becalled in to deal with the
chemicals and potential spills.
While they all worked quicklyand were able to get all the
(11:00):
injured out within 45 minutes,it would be hours before they
were able to open a single lanein either direction.
Clearing all the wreckage awaywould take several days.
The NTSB investigation thatfollowed was forced to rely on
eyewitness accounts, policereports, and aerial photography
to reconstruct the accidentsince the cleanup and reopening
(11:22):
the highway prevented them fromdoing the reconstruction on
site.
It would be years before theyreleased their findings in 1992.
In their report, they placed theblame on the drivers for
responding to the sudden loss ofvisibility by driving at wildly
different speeds.
They also identified other majorsafety concerns that helped play
(11:42):
a part in the pile-up, alongwith their recommendations to
deal with the issues.
Recommendations that includedthe installation of a fog
detection system and a system towarn and slow drivers through
the area when fog is present.
The report also stated that thesettling ponds and steam from
the bow water plant and othernearby plants may have played a
(12:04):
role in the formation of thefog, but they stopped short of
outright blaming them.
Some meteorologists blamed thefog on the day of the accident
to a temperature inversion sincethere had been a rapid 32-degree
temperature change from the daybefore.
Most people though leanedtowards it being Bow Water's
fault.
There had been a study donepreviously in 1979 of the area
(12:28):
that pointed at the Bullwaterponds being a major factor in
causing fog in the area, but thestudy called for further
research and study of emissionscoming off the ponds to
determine this.
While a study was eventuallyfunded, it never happened.
And it had absolutely nothing todo with Bullwater possibly using
(12:49):
political pressure to squash thestudy.
Not to worry though, becauseBowwater conducted their own
study later in 1979.
And come on, there's nothingsuspicious at all of a company
investigating themselves aftersquashing an outside
investigation.
And while they did find that theponds contributed somewhat to
(13:10):
the fog, they would never sayexactly how much.
And I wonder why.
However, the Department ofEnergy concluded in their study
in 1981 that the Bow Water pondsmade the presence of fog three
times more likely.
Strange that the Bowwater studydidn't mention that at all.
Bowwater would continue to denyany responsibility for the fog
(13:32):
that formed and instead claimthat the dense fog had been a
natural occurrence even beforethey had opened up and began
running operations in the area.
They would also go on to accusethe state of Tennessee of
failing to implement necessaryfog detection and warning
equipment along that stretch ofI-75, which technically, yeah,
(13:53):
they are right on that.
Slapping up a couple of blinkylights don't really cut it
sometimes.
But they would also go on toagree to an out-of-court
settlement of$10 million, whichcomes out to about 19 million in
today's money.
With 44 victims and familymembers of victims in January of
(14:16):
1994, they also agreed to limitthe usage of the 235-acre pond
closest to the interstate.
Which, sounds like to me, someshitheads at Bowwater had a
guilty conscience.
And a lot of people agreed withBowwater's criticism of
Tennessee Department ofTransportation for failing to
put into place a proper fogdetection system after the
(14:39):
accidents in the 70s.
Tennessee's DOT eventually paid$800,000 to settle lawsuits
calling them out for negligenceof conditions in the area.
As a result of the collision,they would go on to institute
several safety measures alongthis section of highway.
The section of I-75 between milemarkers 31 and 39 was designated
(15:02):
as a fog advisory zone or a fogadvisory area, which contains
large warning signs on bothsides of the road in both
directions that warn commuterswhen they are entering and
leaving the area.
They also repainted this sectionwith extra paint markings and
reflectors to make it morevisible.
A$4.5 million computerized fogdetection system was installed
(15:26):
in 1993.
This system monitors three milesof the highway north and south
of the Hawassi River with 9forward scanner visibility
sensors, 14 microwave radarvehicle detectors, and 21 CCTV
cameras.
It is connected to a warningsystem that contains more blinky
lights, electronic signs, andvariable speed limits within the
(15:50):
fog advisory zone, andelectronic controlled swing
gates which would block accessto the interstate from the six
entrance ramps in and near thisstretch of the highway in the
event of dense fog.
This system automatically dropsthe speed limit from 70 to 50
miles per hour when visibilitydrops below a quarter mile and
(16:11):
to 35 miles per hour when thevisibility drops below 480 feet.
And yeah, that all sounds greaton paper, but really are people
actually slowing down?
We all know speed limits arejust suggestions, anyways.
And then the swing gates at theentrance ramps would turn on
when visibility drops below 240feet.
(16:33):
This system started up inDecember of 93, and in 2006 it
got a$6.6 million upgrade thatadded the video cameras.
Since the system was put intoplace, no major multi-vehicle
accidents have occurred alongthis stretch in foggy
conditions.
So, it works a hell of a lotbetter than a couple stupid
(16:55):
blinky lights.
And that was the 1990 i-75 fogdisaster.
Thanks for listening, and if youlike the show, please consider
leaving a rating or review onyour app of choice, and you can
reach out to the show at historyis a disaster at gmail.com with
(17:17):
questions, comments, orsuggestions.
As well as consider followingthe show on social media.
We're on Facebook, Instagram,TikTok, YouTube, a few others,
and share the episode.
Your friends will love it.
Also, take care of yourself outthere.
Chase that dream.
Live for today.
Because tomorrow is neverguaranteed.
(17:40):
Thanks and goodbye.
Tuesdays are great.
You made it past Monday, andyou're now one step closer to
the weekend.
But you still gotta get up waytoo early though.
Get dressed, hop in your car,and deal with traffic and
everyone else wondering why thehell they're up this early.
What could be better than that?
Well, maybe add in some fog.
(00:22):
Because fog always makeseverything better.
You're flying down the highway,then all of a sudden it's like
someone throws a blanket overyour windshield.
You can't see a damn thing, soyou slam into the idiot ahead of
you who decided to stop.
Don't worry though, you're notalone.
Because the guy flying up behindyou is about to tap that ass
(00:45):
too.
And really, is there a betterway to start today?
Just ask the commuters onInterstate 75 in Tennessee who
hit a sudden fog bank and foundthemselves involved in one of
the largest auto wrecks inhistory on Tuesday, December
11th, 1990.
So, what happened?
(01:05):
I'm Andrew, and this isHistory's A Disaster.
Tonight, we're driving into theI-75 fog disaster that resulted
in a 99-car pile-up just outsidethe small town of Calhoun,
(01:26):
Tennessee.
And tonight's episode is broughtto you by Polka Bob's Music
Center.
Polka Bob is currently running asurprise fire sale on accordions
and xylophones.
So come on down and say hi toPolka Bob.
You can squeeze his accordionand bang his xylophones before
deciding to take one home today.
(01:48):
Jeez, that's not creepy at all.
Why was he winking at me when hehanded me the ad to read?
I need better sponsors.
I-75, which runs from theCanadian border in Michigan all
the way down to Miami, Florida,is the second longest
north-south interstate afterI-95.
It runs through six differentstates for just under 1800
(02:13):
miles.
So, obviously, there's gonna besome shitty spots on the
highway.
And one of them just happens tobe outside Calhoun, Tennessee.
This 10 mile stretch of I-75lies 70 miles southeast of
Knoxville and runs from milemarker 29 to 39.
This stretch is in two separatevalleys surrounded by ridges
(02:36):
within the ridge and valleyAppalachians.
Appalachians.
The area has a lot of creeksthat run through these valleys
that flow into the HiawasseeRiver, a major river that cuts
the area in half near where theinterstate crosses.
The Chickamauga Dam, not fardownstream from the area,
(02:58):
creates a reservoir which backsup into this section of the
river, making large lakes nearthe interstate where these
creeks all meet up with theriver.
Also in the area is the BowWater Paper Mill.
The mill is just outside ofCalhoun, close to the interstate
and sitting on the banks of theriver.
At the time, Bow Water ownedland on both sides of the
(03:20):
interstate and operatedwastewater treatment settling
ponds next to it.
Now these settling ponds, and ifyou've ever driven past the
factory or a plant or anything,everyone's seen them, they're
the little lakes that sit outfront.
They're part of a large systemand it's used to help separate
solid pollutants fromwastewater.
Water flows into these ponds andthe heavy solid shit settles to
(03:44):
the bottom of the pond over timeand the cleaner water flows out.
It's part of a whole system, andthe system really has nothing to
do with the accident other thanthese ponds.
So, anyways, all that to sayit's a low-lying area with lots
of cold air and a ton of waterin the area.
Put all that together and yougot the perfect recipe for fog
(04:06):
soup.
Thick, nasty fog soup that canpop up in the area at any time
without warning.
If you live in the area orregularly drive through here,
like truck drivers, at somepoint you got caught in this
shit and have some kind of fogstory.
Since this section of Interstateopened up in 1973, there have
(04:26):
been multiple accidents here.
The first of which happened justwithin three months of the
opening and involved 18vehicles, three deaths, and 10
injuries.
And this was just the first ofmany.
So to help cut down on accidentsin the area, they put up a sign
which read Extreme Dense FogArea, next five miles, along the
(04:48):
stretch in both directions.
The sign contained flashinglights that would activate if
fog was detected.
So, yep, they put up a blinkylight on a sign that most people
aren't gonna pay attention toanyways.
Especially when the lightsflashed non-stop for three days,
like they did in the southboundlane prior to the accident, or
(05:09):
just didn't work at all like thenorthbound lanes.
And they put these signs upafter another 18 vehicle
accident occurred in 1979.
And since they put these signsup, there was no major accidents
at all throughout the 80s.
Although I highly suspect theyhad more to do with the
Tennessee Highway Patrol thanthe stupid blinky lights.
(05:33):
On foggy days, troopers wouldsit at the end of the foggy area
and well seeing a cop sitting,everyone's gonna slow down.
So there's that.
The Highway Patrol would also doroutine fog checks in the area.
Which brings us to December 11thof 1990.
During their early fog checks at5.30 and 8 o'clock, Highway
(05:55):
Patrol noted no fog in the area.
However, by 9 a.m.
the fog started rolling in.
Visibility was dropping as themiles ticked by and the fog grew
thicker, dropping from 20 feetto 10 to barely seeing past the
hood of your car.
At 9.10, a semi traveling in thesouthbound lanes carrying
(06:15):
daikumo peroxide in separatetanks slowed to 35 miles per
hour.
Unfortunately, the semi unseenin the fog ahead of them had
slowed to 25 and was rear-endedjust 100 feet south of the State
Route 163 overpass.
The truck drivers got out andattempted to check for damage
and bullshit for a few minutesbefore a 91 Oldsmobile sedan
(06:40):
smashed into the rear of thechemical semi.
Before anyone could move, theOldsmobile was crushed under the
semi and set on fire when it wasrear-ended by another semi.
Neither the driver or thepassenger of the Oldsmobile made
it out of the car.
This was the first, but far fromthe last cluster of accidents in
(07:01):
the southbound lanes.
At 9.15, the first accidenthappened in the northbound lanes
when an 87 Ford Escort slammedinto an 87 Honda near the
overpass, which in turn wasrear-ended by an 83 Toyota
pickup, which was then hit by a1990 Pontiac, which was then in
(07:22):
turn hit by an 89 Oldsmobile.
Surprisingly, no one was injuredin this mess.
As the minutes ticked by, thestopped commuters could hear the
sounds of impact, the screech ofbrakes, the crunching of metal
on metal, the secondaryexplosions as fuel tanks
ignited.
Some slowed or stopped to try tosee what was happening.
(07:42):
The stopped or slowed movingvehicles invisible in the fog,
waiting to be struck by driversstill traveling at a high rate
of speed.
Within minutes of the firstaccident, both directions of the
interstate had become a tanglednightmare of wreckage spanning
hundreds of yards.
Vehicles were crushed, stacked,thrown into positions that
(08:03):
seemed to defy physics.
Tractor trailers jackknifedacross multiple lanes.
Cars were smashed down tofractions of their original
size, wedged beneath largervehicles or sandwiched between
them, and still more vehicleskept coming.
Drivers emerged from clearconditions into fog with zero
warning, finding themselvessuddenly confronted with walls
(08:25):
of stop traffic and wreckage.
Even those who managed to breakcouldn't stop in time.
It was far too late.
The pile of wreckage just grewlarger.
Ten minutes after the firstcollision, the final accident
occurred.
Accidents in the southboundlanes involving 72 vehicles
(08:48):
would stretch for a fifth of amile north of the overpass.
The northbound lanes, a total of27 vehicles would be involved in
multiple accidents stretching aquarter mile south of the
overpass.
The first 911 calls startedcoming in as the first
northbound accident happened.
Within minutes, Bill Dyer of theBradley County Sheriff's Office
(09:10):
was on scene.
Being the first on scene, heoriginally completely missed the
first accidents in the fog.
He had to turn around and driveback to find the scene.
When he got back to the area, aseriously injured man stumbled
out of the fog and towards hiscruiser.
When he exited the cruiser tohelp the man, he could hear the
metal-on-metal sounds ofmultiple accidents just north of
(09:33):
his location.
As he got closer, the screams ofthe wounded got louder.
After seeing what he could ofthe devastation, he immediately
called for backup in emergencyservices.
Over 200 first responders wouldend up on site from as far away
as Chattanooga and Knoxville.
By 9.30, the Tennessee EmergencyManagement Agency began
(09:55):
coordinating the responsebetween the 33 different
departments who answered thecall for help.
Within minutes, the TennesseeHighway Patrol had the highway
shut down on both ends.
McMaine County EMS set up triagein the median north of the
overpass to evaluate the woundedas they were pulled from the
wreckage.
While Bradley County EMS set upanother triage site to the
(10:17):
south.
42 survivors were treated forinjuries ranging from minor cuts
and scrapes up to more traumaticinjuries that required
hospitalization.
The injured would be transportedto hospitals as far away as
Chattanooga and Knoxville.
In total, eight people died inthe fires raging across the
wreckage, and four more had diedas a result of injuries
(10:39):
sustained in the crash.
Firefighters from multipledepartments worked the fires
that had spread throughout thearea.
Most concerning was the presenceof chemical tanks containing
peroxides that were sendingflames 30 feet in the air.
Special hazmat teams had to becalled in to deal with the
chemicals and potential spills.
While they all worked quicklyand were able to get all the
(11:00):
injured out within 45 minutes,it would be hours before they
were able to open a single lanein either direction.
Clearing all the wreckage awaywould take several days.
The NTSB investigation thatfollowed was forced to rely on
eyewitness accounts, policereports, and aerial photography
to reconstruct the accidentsince the cleanup and reopening
(11:22):
the highway prevented them fromdoing the reconstruction on
site.
It would be years before theyreleased their findings in 1992.
In their report, they placed theblame on the drivers for
responding to the sudden loss ofvisibility by driving at wildly
different speeds.
They also identified other majorsafety concerns that helped play
(11:42):
a part in the pile-up, alongwith their recommendations to
deal with the issues.
Recommendations that includedthe installation of a fog
detection system and a system towarn and slow drivers through
the area when fog is present.
The report also stated that thesettling ponds and steam from
the bow water plant and othernearby plants may have played a
(12:04):
role in the formation of thefog, but they stopped short of
outright blaming them.
Some meteorologists blamed thefog on the day of the accident
to a temperature inversion sincethere had been a rapid 32-degree
temperature change from the daybefore.
Most people though leanedtowards it being Bow Water's
fault.
There had been a study donepreviously in 1979 of the area
(12:28):
that pointed at the Bullwaterponds being a major factor in
causing fog in the area, but thestudy called for further
research and study of emissionscoming off the ponds to
determine this.
While a study was eventuallyfunded, it never happened.
And it had absolutely nothing todo with Bullwater possibly using
(12:49):
political pressure to squash thestudy.
Not to worry though, becauseBowwater conducted their own
study later in 1979.
And come on, there's nothingsuspicious at all of a company
investigating themselves aftersquashing an outside
investigation.
And while they did find that theponds contributed somewhat to
(13:10):
the fog, they would never sayexactly how much.
And I wonder why.
However, the Department ofEnergy concluded in their study
in 1981 that the Bow Water pondsmade the presence of fog three
times more likely.
Strange that the Bowwater studydidn't mention that at all.
Bowwater would continue to denyany responsibility for the fog
(13:32):
that formed and instead claimthat the dense fog had been a
natural occurrence even beforethey had opened up and began
running operations in the area.
They would also go on to accusethe state of Tennessee of
failing to implement necessaryfog detection and warning
equipment along that stretch ofI-75, which technically, yeah,
(13:53):
they are right on that.
Slapping up a couple of blinkylights don't really cut it
sometimes.
But they would also go on toagree to an out-of-court
settlement of$10 million, whichcomes out to about 19 million in
today's money.
With 44 victims and familymembers of victims in January of
(14:16):
1994, they also agreed to limitthe usage of the 235-acre pond
closest to the interstate.
Which, sounds like to me, someshitheads at Bowwater had a
guilty conscience.
And a lot of people agreed withBowwater's criticism of
Tennessee Department ofTransportation for failing to
put into place a proper fogdetection system after the
(14:39):
accidents in the 70s.
Tennessee's DOT eventually paid$800,000 to settle lawsuits
calling them out for negligenceof conditions in the area.
As a result of the collision,they would go on to institute
several safety measures alongthis section of highway.
The section of I-75 between milemarkers 31 and 39 was designated
(15:02):
as a fog advisory zone or a fogadvisory area, which contains
large warning signs on bothsides of the road in both
directions that warn commuterswhen they are entering and
leaving the area.
They also repainted this sectionwith extra paint markings and
reflectors to make it morevisible.
A$4.5 million computerized fogdetection system was installed
(15:26):
in 1993.
This system monitors three milesof the highway north and south
of the Hawassi River with 9forward scanner visibility
sensors, 14 microwave radarvehicle detectors, and 21 CCTV
cameras.
It is connected to a warningsystem that contains more blinky
lights, electronic signs, andvariable speed limits within the
(15:50):
fog advisory zone, andelectronic controlled swing
gates which would block accessto the interstate from the six
entrance ramps in and near thisstretch of the highway in the
event of dense fog.
This system automatically dropsthe speed limit from 70 to 50
miles per hour when visibilitydrops below a quarter mile and
(16:11):
to 35 miles per hour when thevisibility drops below 480 feet.
And yeah, that all sounds greaton paper, but really are people
actually slowing down?
We all know speed limits arejust suggestions, anyways.
And then the swing gates at theentrance ramps would turn on
when visibility drops below 240feet.
(16:33):
This system started up inDecember of 93, and in 2006 it
got a$6.6 million upgrade thatadded the video cameras.
Since the system was put intoplace, no major multi-vehicle
accidents have occurred alongthis stretch in foggy
conditions.
So, it works a hell of a lotbetter than a couple stupid
(16:55):
blinky lights.
And that was the 1990 i-75 fogdisaster.
Thanks for listening, and if youlike the show, please consider
leaving a rating or review onyour app of choice, and you can
reach out to the show at historyis a disaster at gmail.com with
(17:17):
questions, comments, orsuggestions.
As well as consider followingthe show on social media.
We're on Facebook, Instagram,TikTok, YouTube, a few others,
and share the episode.
Your friends will love it.
Also, take care of yourself outthere.
Chase that dream.
Live for today.
Because tomorrow is neverguaranteed.
(17:40):
Thanks and goodbye.
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