Data helps analyze traffic accidents
Trooper Matthew Johnson walked up to a white board and started scribbling.
“Let’s say you’re driving your vehicle down the road and you skid here and stop here,” Johnson said, drawing a 2D car, followed by horizontal lines picturing the vehicle’s trajectory.
“That’s 30, a constant, times the distance the car skids, 45 feet, times the coefficient of friction of the road,” he continued, quickly drawing a formula that looked simple enough when he did it.
He turned to his partner, another crash reconstruction specialist at the Wisconsin State Patrol.
“Mike, calculator,” he said.
“It’s 34.74 mph,” Michael Smith replied.
“So we know that the speed here, at the start of the skid, was 34.74 mph,” Johnson finished confidently. “It’s physics.”
Although the exercise was impressive, Johnson said: “That was an easy one.”
Stationed in Waukesha and covering southeastern Wisconsin, Smith and Johnson are one of 13 Wisconsin State Patrol crash reconstruction specialist teams. They are the troopers behind reports that contain vital information on traffic accidents.
Most of their work is done by collecting evidence at accident scenes. They later use that information to determine who was at fault, how fast cars were going, whether the driver broke sufficiently, among other factors.
They also use airbag control or sensing and diagnostic modules—dubbed “black boxes.” These devices record crash information just before airbag deployment.
Most newer cars have them, Smith said. If a vehicle has airbags, it likely has an airbag control module.
National attention was focused on the modules recently after a series of recalls by Japanese automaker Toyota, whose cars had an issue with sudden acceleration. Now, lawmakers in Washington are working on a bill that would require black boxes to be standard.
Recording modules are always activated, but they only record information seconds before airbag deployment. The information varies, but it usually includes speed, braking information, acceleration and deceleration of the vehicle.
The recording modules have been around for a while.
“I prosecuted one about 11 years ago,” said Steve Madson, the assistant district attorney responsible for most traffic prosecutions in Walworth County. “They have been around for quite a while. But now they’re more and more prevalent in cars.”
Smith said legislation in Congress could help crash reconstruction and investigation work. Currently, each automaker has its own device to read the information recorded. Toyotas and Mazdas, for example, are nightmares for crash reconstruction specialists.
“Two years ago, we had a crash involving a Mazda, and we just knew we wouldn’t be able to download the data,” he added.
Currently, the Wisconsin State Patrol can read data from Ford, Chrysler and General Motors vehicles. For other automakers, the State Patrol must request data from the companies, losing ground on investigations and slowing prosecutions.
The bill would make reading instruments standard across the industry, the troopers said.
On the prosecution side, Madson said, it helps to have data obtained from recording modules.
“It certainly is a good indication of the crash analysis,” the prosecutor added. “That is helpful, and it definitely makes a stronger case. But it isn’t fail safe.”
In some crashes, the airbag isn’t deployed, Johnson explained. And when that happens, the system doesn’t record any data.
So for now, Johnson and Smith will continue to be much needed parts of crash investigation in the state scene. Machines are useful to corroborate investigations, but they’re yet to replace human investigators.
“You still need physical evidence and science to supplement the data,” Smith said.
“It’s just like any other mechanical device,” Johnson continued. “It just states data.”
May 12, 2010 at 5:51 p.m.
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Beeferer:
"The coefficient of friction of the road is a constant
Wrong... New concrete will differ from worn, as it differs from asphalt, snowy roads, wet roads, etc...
"the coefficient of friction of a tire differs with size, surface area (which changes with air pressure- an under-inflated tire has more surface contact with the road than an overinflated tire), tread pattern, weight of the vehicle-
Wrong... kind of... the amount that it changes will not factor in the speed of a vehicle the change in the coefficient of friction will be so small that it won't change the speed any.
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There are so many other variables that come into play that one cannot possibly say that the coefficient of the friction of the road and the length of skid marks can give you the vehicle speed.
Wrong again, yes, it can and they do it all the time.
An empty cement truck with new tires traveling @ 30 miles per hour won't skid as far as a Yugo traveling @ 30 miles per hour on bald tires. I'm just saying..."
Wrong... If they both have 100% braking then they will stop the same, I know your going to have a hard time wrapping your mind around that one but it's physics
May 12, 2010 at 5:35 p.m.
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Planet:
"In answer to your second post, these databases contain names, addresses, phone numbers, dates of registrations, vehicle vin's and descriptions. These databases also contain driving records, including licenses that have been suspended or revoked."
Well, I went to Woodman’s yesterday, and wrote a check. That check has my address, phone number, and driver's license number??? Maybe police can go there.
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It doesn't take much detective work to determine expired/invalid registrations, registered vehicles to revoked drivers, expired registrations to operating vehicles.
Your right, I can't imagine it does. However, you can have all the information in the world; it doesn't change the fact that people are still going to drive with out a license, or valid vehicle registration. The same way all the street signs we have don't stop people from speeding, run stop signs, and turn left after the left arrow turns red.
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Truth1,
I have to disagree with you, when you say: "Guardian makes great points..Its really odd how a felon can't possess a firearm because they "might" cause harm with it."
So, because their a felon they are not caring guns or have a gun available to them? It's as if you’re saying that since they were caught and convicted as a felon, now they will never carry a gun again? Just as the Planet guy is saying, just because somewhere tucked in a computer someone may know you’re a revoked driver, or your registration is suspended those people are still going to drive. Their suspended for a reason; being caught isn't going to change anything.
May 11, 2010 at 2:59 p.m.
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“That’s 30, a constant, times the distance the car skids, 45 feet, times the coefficient of friction of the road,” he continued, quickly drawing a formula that looked simple enough when he did it.------ The coefficient of friction of the road is a constant, but the coefficient of friction of a tire differs with size, surface area (which changes with air pressure- an under-inflated tire has more surface contact with the road than an overinflated tire), tread pattern, weight of the vehicle- there are so many other variables that come into play that one cannot possibly say that the coefficient of the friction of the road and the length of skid marks can give you the vehicle speed. An empty cement truck with new tires traveling @ 30 miles per hour won't skid as far as a Yugo traveling @ 30 miles per hour on bald tires. I'm just saying...
May 11, 2010 at 12:59 p.m.
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Guardian makes great points..Its really odd how a felon can't posess a firearm because they "might" cause harm with it but a felon driver or one that SHOULD be classified as a felon by their actions can posess a drivers license AND a motor vehicle..Lunatics running the asylum.
May 11, 2010 at 8:10 a.m.
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Oops, I meant the_one, sorry
May 11, 2010 at 8:10 a.m.
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Geez, get off my back will you? Guardian, I did not make any statement against you. Have a good day.
May 10, 2010 at 10:30 p.m.
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Re: The One
In answer to your first post, I know I should ignore it, as it contains no relevant information, but it is a mystery why you keep writing "Gardians". I suspect your computer may be missing a you.
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In answer to your second post, these databases contain names, addresses, phone numbers, dates of registrations, vehicle vin's and descriptions. These databases also contain driving records, including licenses that have been suspended or revoked.
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It doesn't take much detective work to determine expired/invalid registrations, registered vehicles to revoked drivers, expired registrations to operating vehicles.
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I can imagine all kinds of ways to use this data to reduce the number of bad drivers on the road.
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Tune in for my next show where we will discuss relational databases, and why they have nothing to do with your family reunion.
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Have a pleasant evening :-)
May 10, 2010 at 9:46 p.m.
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Gardians_of_the_Planet:
"It just ticks me off, with the DOT, DMV, and Circuit Court databases fully available to law enforcement, why do we continue to have multiple DUI offenders, unregistered vehicles, unlicensed drivers, and people driving after revocation, out driving in public?"
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Please, go back to your planet now… You lack at least one important trait to live on this planet… Common Sense! Leave while you still can. But, before you go, can you tell me how any of these offices have anything to do with controlling the bad choices of others, or help officers enforce traffic laws on those individuals? I mean what would any of the offices you mentioned have anything to do with; multiple DUI's unregistered vehicles, unlicensed drivers, or driver's driving after revocation.
People need to put blame where it belongs on the individual, and stop using their scapegoats to deflect responsibility to where it doesn’t belong. HUH… It’s kind of sounding like a GM thread… right Justme46
May 10, 2010 at 9:15 p.m.
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Patch, "invertebrates" is exactly the right word...Thank you!
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It just ticks me off, with the DOT, DMV, and Circuit Court databases fully available to law enforcement, why do we continue to have multiple DUI offenders, unregistered vehicles, unlicensed drivers, and people driving after revocation, out driving in public?
Your right, it must be the invertebrates.
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Just think, Omar Miguel Lopez is now serving his fourth month, of the five year sentence.
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http://gazettextra.com/news/2010/jan/21/...
May 10, 2010 at 8:43 p.m.
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Guardian was just being sarcastic or maybe trying to joke around? I don't think he/she is serious. JMO
May 10, 2010 at 8:40 p.m.
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Privatize law enforcement to get the criminals off the road? You forget that law enforcement is only the first step in the criminal justice system. You could privatize all the cops in the nation and it would not do any good with the invertebrates that we have working in our DA offices.
May 10, 2010 at 8:27 p.m.
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Gardians_of_the_Planet:
I got to ask, exactly what planet are you the guardian of... With comments like yours, it can't be Earth! A little common sense please! Maybe a quick spell check is in order too, your Gardians is missing a "U" its gUardians!
May 10, 2010 at 8:12 p.m.
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If an unregistered vehicle, driven by an uninsured motorist, who's driving after revocation, runs over a motorcyclist, while talking on the phone, changing a CD, and spills their beer on the GPS unit, when it said to turn left NOW, but never applies the brakes, how fast was the vehicle going?
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It's purely a mystery to me why there are so many accidents, (sarcasm).
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Let's privatize traffic law enforcement, and get these criminals off the road. What we have now isn't working.
May 10, 2010 at 7:51 p.m.
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Yeah, they have that. It's called OnStar. Justsayin...
May 10, 2010 at 7:09 p.m.
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It also wouldn't be hard or expensive to add a GPS to the black box, and record the car's whereabouts for it's entire lifetime. The police could download the data, and determine every single time the speed limit had been broken, too.
I'm just sayin'...
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