Krankor

Alright, I'm never one to be shy about flaunting my ignorance. So here goes:

Don't these things have antilock brakes? How do you get 120 feet of skid marks with antilock brakes?

BunnyGirl

My friend worked back from the estimated speed of 80 miles per hour at initiation of the fall over the wall to calculate determine a speed along with slowing during the 410 feet along the barrier up an incline, to try to reach the estimate of 115 MPH at impact (which at this time is being worked on as a starting point based off 9-1-1 phone calls by motorists reporting a car speeding out of control just minutes before the accident happened), and also calculating the skid marks left before impact on the wall. This is how he arrived at approximately 140 miles per hour. He was also calculating in resistance, although not sure of the exact since he doesn't have an exact brake force applied by the car (which is doubtful the police can figure out to a certainty, generally get an approximate range and average it, which is how they get their ranges). He also said the initial estimated speed will more likely than not go up as to how fast they were traveling, as in the majority of instances it does, such as the 120 mile per hour Ferrari carsh that is now stated to be going in excess of 160 MPH. Initial estimates are usually conservative.

There should probably be more information in the next week or two as to what was actually determined so it should be interesting to see what they find.

BunnyGirl

I haven't seen actual photos of these skid marks to know if they are continuous or a skip pattern or what they are but the news and the diagram reconstruction have been stating 120 feet of skid marks on the road before impact and then the 410 feet of skid marks on the wall before going over, projecting 224 feet through the air away from the bridge, while plummeting 58 feet below.

I don't have a better answer to that one either.

neit_jnf

"How do you get 120 feet of skid marks with antilock brakes?"

going sideways...

neit_jnf

Yes I assumed angle of 0 deg and no resistance.

Do you actually think police investigators will take into consideration air resistance and rotational "gyro" inertia resistance into their estimates?

stupidCivicstrixAre4kids

why not

Krankor

That was my first thought, but somebody said the skid was due to braking...

My second thought was, if it was skidding sideways, wouldn't it flip over before it went that far? I guess not....

saturn

I have no clue. But it doesn't even matter. If the car spun around a thousand times mid air before hitting the ground that only means it was going even faster than ~80mph as you calculated as more energy would have to be supplied initially to be translated into rotational momentum.

I honestly don't even know what we're taking about anymore. Why does anyone want to know how fast he was going when he flew over the wall? Why does anyone really want to know how fast he was going before he hit the wall initially?

I seriously doubt the kid went from 140 to 115 in 120 feet. With an average deceleration that gives you an average speed of 127.5 mph. At that speed it takes 0.64 seconds to travel 120 ft. That means you're pulling about 1.8g's of deceleration of braking. The Bugatti Veyron claims to be able to brake at 1.3g's. It just doesn't add up.

Feel free to let me know if I'm missing something, cause right now I just don't see it.

neit_jnf

because it's too complicated and not needed. just knowing it was over 100 and alcohol was involved is enough

John Corbitt

The car was launched. it didnt go off at 0 degrees. Therefor the departure speed was less than 80mph.

neit_jnf

but there are more variables there... it required energy enough to go over the barrier and if we factor in the rotational inertia and air drag then there's more energy needed so the initial estimated speed goes back up

BunnyGirl

My math geek friend was doing some more calculating with this and called me this morning all excited that he thinks he figured out their speed range (this time figuring the car started skidding sideways before it hit the wall instead skid marks with hard breaking). He said he was factoring in other variables (I don't know what exactly) and he said that (assuming they hit the wall at about 115 miles per hour as the police are initially reporting) they started out roughly at 127 miles per hour when the skid marks started, but said that doesn't really explain how they skidded 410 feet along the barrier up an incline and were still able to fly that far after they went over it. He said either the estimated speed at impact is wrong or they were still accelerating hard during the skid. He said he could do a better job if he had an actual outline of the exact angles and directions involved with this accident. He said if you don't assume the estimated speed the police gave at impact and calculate back based on trajectory off bridge, gravitational forces and resistance both on the way down and also along the bridge including the skid marks over the full length (wall and road) this calculates out to somewhere between 134-138 miles per hour. Again, since road angles and impact angles aren't know, he can't be more specifically. He sald if it was windy and depending on wind direction they could have had yet another different speed range.

Labop

Your "math geek friend" wouldn't happen to be one of the people who write into the show NUMB3RS when they get something wrong... would he?

BunnyGirl

LOL. I have no idea. In college he majored in accounting and minored in physics and now works for a casino/resort company in Las Vegas.

antiver

*cheersfordarwin* *criesfortheotherkidsinthecar*

DrKillJoY

UPDATE

Speed limit lowered near crash site

RALEIGH — Transportation officials lowered the speed limit by 10 mph near where four Wakefield High School seniors died March 4 when their speeding car flew over an elevated section of a highway.

The speed limit is now 55 mph on U.S. 64/264 West from New Hope Road to the highway’s intersection with the I-440 Beltline, said Jon Nance, a division engineer for the N.C. Department of Transportation. It was 65 mph beforehand.

The change did not come in response to the deaths of Baker Wood, 18, Steven George, 18, Anthony Bostic, 17, and Timothy Steinberg, 18, who died when Baker drove his father’s Mazda RX-8 more than 100 mph around a highway overpass.

“There were a lot of other speed limit signs that they chose not to follow,” Nance said.

Engineers began looking into dropping the speed limit shortly after the interchange opened in July 2005, Nance said. Speed advisory signs were also put up on the overpass.

Chrisbert

That'll solve the problem. They were going more than twice the new speed limit as it were.

DrKillJoY

Engineers began looking into dropping the speed limit shortly after the interchange opened in July 2005, Nance said. Speed advisory signs were also put up on the overpass.

BunnyGirl

Speed limits are only for those who choose to obey them. They can put up all the speed signs in the world and unless anyone actually follows them, then there is no point. Like these people, speed limits were irrelevant. Going over 100 in a 65.

Chrisbert

Either way, it would not have helped. Maybe they could apply the useless gun-control logic to cars. "Who needs a clip that holds more than 10 rounds?"

Who needs a car that can go more than 65mph?

Krankor

Shut up! Don't give them any ideas!

expo1

UPDATE :

Driver of the RX-8 had a blood alcohol level of .21 STORY

Moostafa29

Wow, I hadn't heard about this. Thats too bad. Guess in this case, it wouldn't matter if it was silver or not.

BunnyGirl

You can bet there will now be several wrongful death lawsuits filed by the parents of the other kids.

Glyphon

i doesn't mention it in the article, but i would suspect that the other passengers were drunk as well.