are there any online accident simulators available to the public?

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Lainey
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are there any online accident simulators available to the public?

Post by Lainey »

I recently rear ended someone who was very upset with me because I tried to go around him when he was stopped in the road a few minutes earlier, and so further down the road he just randomly slammed on the brakes, and it was wet, so I braked, slid, and hit him.

After the accident, I asked why they slammed the brakes and came to a complete stop in the middle of the road. He said that they were slowing down, not stopping, but I am sure he slammed and was completely stopped when I hit him. I think I pushed him a wee bit, but there were no marks on the road as it was wet.

Now I am trying to figure out if there are any clues from where the cars ended up as to whether he was moving or stationary. We ended up with the cars directly my front to his back, less than an inch apart. I would have thought that if he was moving and I hit him, he would have been propelled forward and we would not have stopped so close together. I am not sure how to predict what the movements would be under the two possibilities (where he was moving vs where he was stopped) and I am wondering if there is some kind of physics modelling program or online tool of any kind that would allow me to play with the two possibilities in order to determine whether there is some evidence in the final positions of the car that would help me demonstrate that it was not true that he was simply slowing down. Thanks.

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Bob Anderson
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Re: are there any online accident simulators available to the public?

Post by Bob Anderson »

Where on the roadway the vehicles came to rest and the extent of their damage may be more important to addressing your issue than how close they were at rest, since this gives an indication of the combined momentum of the two vehicles at impact and how forceful the impact was. Certainly, if there was indeed only inches of post-impact motion of the vehicles, I would say that the front vehicle was either stopped or very nearly stopped at impact.

As you have stated, the vehicles ordinarily come to rest with some distance separating them in rear-end impacts, especially when the striking vehicle is braking/skidding at impact. This is because impacts have somewhat of a bounce so that the front vehicle is traveling a little faster than the rear vehicle immediately post impact, combined with the fact that rear-end impacts tend to remove the front driver's foot from the brake.

Skidding into the impact, your forward body motion would only enhance your brake pedal force, so that the vehicles coming to rest nearly touching indicates that the front driver was also hard braking throughout the event, in spite of the tendency for the impact to remove his foot from the brake pedal. This could be either because it was a particularly minor impact, consistent with what you have indicated with only inches of post-impact movement and/or the front driver was aware, braced and hard braking in anticipation of possible impact, which is also consistent with what you have described.

There is always a chance that either your vehicle or the front vehicle's airbag control module has an event data recorder function that recorded the pre-crash speeds and braking and/or speed changes during the crash. What were the year make and model of the vehicles involved in your crash?
Bob Anderson
Tempe, Arizona

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Avanice
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Re: are there any online accident simulators available to the public?

Post by Avanice »

Whilst the leading driver may have braked sharply never forget the fault of the following driver who could not take avoiding action in time. Had that other vehicle been the (traditional) child running into the carriageway would you have hit that child? Or, had the other vehicle been braking for an object (person) in the carriageway which you could not see, would you have pushed the leading vehicle into and over that object?

The narrow gap between the vehicles does suggest the leading driver was braking or possibly that they were stationary and you had very nearly stopped on impact or even that the vehicles had locked together and separated just before stopping. There are other things to look at, such as the height of the impact marks. Weight transfer under braking lowers your front and raises their rear.

An incident such as this cannot be resolved by any software I am aware of and it would need an examination of both vehicles to make any determination. This style of incident makes data recorders and your own in-vehicle camera into self protection devices.

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Lainey
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Re: are there any online accident simulators available to the public?

Post by Lainey »

Mainly I was interested to see the differences in what happened upon rear impact between a vehicle in front that was moving versus one that had stopped. I had my intuitions about what the differences were, but intuitions are not always correct, which is why I was looking for some sort of tool that would let me explore the different situations.

I did think there would be transfer of energy from my vehicle to the one in front, which I expected would propel it further than me, as I was braking, skidding, and lost energy in the impact. I was confused about how the driver could say they were just slowing down, yet ended up stopped literally an inch in front of my vehicle. My memory of the accident (that I don't feel confused about) is that the car in front came to a very fast complete stop. In my country (UK) cars have a duty of care to others on the road, so that while the car in back is usually completely to blame for a rear collision, in some incidents (for instance, where a driver is acting out of road rage and slams on the brakes where there is no emergency present) the driver in front shares the responsibility for the accident.

Now, I had never heard of event data recorders in airbag control modules, and this is fascinating as well as potentially very helpful! I have an old car (a 1999 Mercedes e240), and so I doubt that this technology was in my car, and so far my internet searches seem to indicate this is true, but I need to look further to get a definitive answer. The car in front was a 2008 Vauxhall (chevrolet) Corsa, and I can see that the later 2009 models had the event data recorder, but I can't confirm whether the 2008 did or not. Is there a database somewhere that lists the cars that do? I think I found one for the US, but I need to see if there are any in the UK. Many thanks for suggesting this!

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Lainey
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Re: are there any online accident simulators available to the public?

Post by Lainey »

Hi Avanice,

I think all parties concerned would agree that I was braking, but the contention lies with whether the car in front had braked and come to a complete stop (where the rear of the car would have presumably come to its normal position), or whether he was just slowing down, and where the rear of his vehicle would have been slightly elevated (as when braking gently as in "slowing down"). Do you think we could determine whether he was slowing down vs stopped based on the damage to the cars?

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Bob Anderson
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Re: are there any online accident simulators available to the public?

Post by Bob Anderson »

Unfortunately, that question can't be answered until you can see what you've got. There are a lot of things that affect ride height, including the amount of cargo and occupants in a vehicle. I still remember an inspection many (many) years ago when the driver got out of the vehicle, the bumper height I was measuring came up an entire inch! Granted it was a small car and he was a big guy. This is significant because hard braking may only change the bumper height dynamically by 2 to 4 inches. My point is that that is a complex problem and you may or may not get an answer, depending on what you get.
Bob Anderson
Tempe, Arizona

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