db4690: “Mythbusters has little credibility, as far as I’m concerned” I attempted to address this with my statement of: “Mythbusters with the usual amount of creativity”. Many times when they fail to get something to blow up on it’s own they resort to C-4!
It could happen I think. A case of the tidily wink effect.
Vehicles have a lot of mass and travelling even at moderate speed build up a lot of kinetic energy. There’s been some posts here showing where occupants ejected during a crash are thrown 20 or 30 feet or more into the air during a roll-over type of crash. That same energy if directed just so could pop a manhole cover like that. That’s my guess and I’m sticking with it.
Yosemite: Thank you for clarifying “Jennerhole” cover (sexual orientation confusion). For some forgotten reason many years back I researched manhole cover weight and it was around 150 pounds. I guess 200 pounds is in the ballpark.
I’ll admit I only ever watched a few mythbusters episodes
Anyways, the most outrageous one I remember was when they were trying to “determine” if it would be possible for a bullet to blow through a rival sniper’s scope, and enter his skull, killing him
They first tried it at a reasonable distance . . . no go
Then they got closer . . . no go
Then they went right up to the other scope . . . no go
Then they went right up to the other scope, and fired some kind of round which a sniper in all likelihood wouldn’t use . . . bingo
“credible” :trollface:
I guess if you want to hit a bullseye, the best way to ensure success is to go right up to the bullseye and unload, point blank, for example 
I may have gotten the details slightly wrong . . . remember this episode was several years ago, and I just said I’m not a real mythbusters fan, anyways 
The average Joe at Gold’s gym isn’t impressed by 150 pounds.
Some of the comments here remind me of the guys that said after the shuttle reentry disaster that a lightweight insulating tile couldn’t possibly punch a hole in the wing of the shuttle… until an experiment punched a hole the size of a basketball with a tile.
A tire on a truck… or even a car… could easily throw a 150 pound Jennerhole cover up if its seating ring was broken or unstable… and many in the Boston area are.
On an aside, I like the term Jennerhole. I think I’ll start using it regularly. It’s gender-neutral!
Suction from a passing vehicle will not launch the cover. An explosion or a sudden built up of pressure could.
On Mythbusters they generally test a myth from both directions. In other words, they test the circumstances of the myth. If the circumstances do not produce the purported result, they go back and try to determine, what circumstances WOULD have to occur to produce the purported result.
Ever see the episode where they tested bizarre substitutes for a spare tire? They tried logs, stuffing a flat tire with hay, and eventually, using a Jennerhole cover as a “tire”. The episode was taken to it’s absurd climax, having Adam run an obstacle course driving a car with all 4 tires replaced with Jennerhole covers, and he was sliding around knocking over cones right and left. It was hilarious!!!
So the present theories are:
- Explosion
- Suction of SUV passing over
- Dislodged and then flipped up from tire of SUV.
- Support broken and then flipped up
(2,3,4 assume welds are missing or broken)
my vote is for #3
Edot: Here is what data is available: video from highway cameras shows an SUV changing lanes in front of Clavette’s car. Not much can be seen, but officials believe that vehicle passed over the manhole cover, dislodging it and sending it through the air and into the windshield of the Honda.
We receive the Indianapolis, IN tv stations and for a period of time, there was a problem with explosions causing the manhole covers to blast into the air. Protective restraints have now been installed to prevent these covers from doing more than lift up a few inches in the event of an explosion in the underground tunnels. The problem of the explosions seems to have been solved and replaced by daily shootings so that the tv news channels have something to report.
Back in 1963_when I was a grad student at Southern Illinois University I witnessed an explosion that sent a,manhole cover about 10 feet in the air. This manhole was under a sidewalk and it was fortunate that it wasn’t during a class change where there might have been serious injuries. The resulting power outage lasted several hours. The computer was down almost a,day while some vacuum tubes were replaced that blew after power was restored. (I can’t remember if the computer was an IBM 1130 or an IBM 1401).
@Triedaq was that the computer that took up the entire basement of Faner hall? Ran punch cards on that one.
@Barkydog I don’t remember a Faner Hall, but the computer could have been located there. The only buildings I remember were Old Main which later was torched in 1970, the Student Union building, Morris Library, Schryock music building and the old house at 611 W. Mill street where we math grad assistants each had a,desk in a large room. I had a room in a house on West Pecan street which I rented for $8 a week. A week’s worth of meals at the Student Center was $14 3_meals 6 days a,week and breakfast and a,Smorgasbord on Sanday. For $22 a,week I had room and board. My assistantship paid $200 a,month. I haven’t lived as well since…
For my exorbitant tuition, we only had one computer on campus, and it was in the science building. Business folks were allowed to use it once a week though for marketing and business analysis. I rented a room from an elderly widow lady for $5 a week in 1969. Then if I agreed to keep her corner lot sidewalk shoveled, I could use the garage.
I tell my children that when I was in college I would have to submit my student I.D. card at the campus library in order to borrow an electric typewriter. I could use it in a room there so I could type my school papers. Editing was a little bigger project than it is with today’s computers. I’m not sure if they get the concept or even really believe me. :neutral:
Also, I remember taking some final exams on 80 punch Hollerith cards!
At least History was easier then… there wasn’t nearly as much of it.
CSA
45 years ago I was cautioning my my from South Dakota about metro driving and you needed to be ready for anything-like a car flying off the road above onto the interstate below. She’s been laughing at me all this time until last week when a car proceeded to crash through the barrier to land on the freeway 40 feet below. Now I hesitate to warn her about flying personhole covers. I might just do that but still I remain skeptical but accept the council of the engineering types here.
You cannot live in fear. Regular caution, like avoiding obviously impaired drivers and being extra alert at 11:00pm when driving past the bars on Main Street or when the roads are bad is prudent. Driving around being in fear of a car crashing through a barrier in the overpass above you or a manhole cover getting made airborne by a truck is irrational. Some things are simply going to happen when they’re due. IMHO warning her about flying Jennerhole covers would be needlessly creating irrational fear.
Now, being afraid to drive in the tunnels in Boston… THAT’s rational!! 
Yeah or anywhere in Boston.
Amen to that!
Now, being afraid to drive in the tunnels in Boston...... THAT's rational!!
And she was driving in a tunnel. I heard on the news that Boston then inspected all 200+ manhole covers in the tunnels. Not sure if they found anything though.
I’m sure they found plenty of loose covers… but they’ll never tell!
Of course, falling tunnel parts (concrete ceiling panels and lights) is an even bigger problem… 
Suspect ignition of sewer gas (methane).
Can’t imagine how a vehicle wheel can flip the personhole cover up.
If it did flip up, would it not hit the underside of the vehicle?