Accident Reconstruction James Dean
As you know, this tragic accident occurred September 30, 1955 at 5 am 45 near Cholame, California He was the subject of numerous independent surveys and research studies over the years recently, National Geographic decided look at it again, using a different approach and new science of the accident.
Their researchers found visual statement and asked us to participate and use a modern approach in a new rebuilding We volunteered with enthusiasm that this was a great opportunity to show the world our latest technology software Therefore, our CEO Mike Kennedy, and our director Mike Greenfield of forensic mapping met the film crew from London, England to Cholame, California in April 2005, to reconstruct the accident in real time at the point of actual accident.
James Dean was en route to a race on amateur road in Salinas, from Los Angeles he was driving his brand new 1955 Porsche Spyder 550, he had just bought for the purpose of his amateur racing activities, he was Rolf Weutherich accompanied by a German mechanic, sent by Porsche to support the new American owners racing Porsches They took a road that made them pass through Cholame, California on Highway 46 Shortly before the accident, Dean was shot by a CHP officer for speeding and ticketed.
5 to 45 pm, Dean going westbound through the intersection Y Highway 41, a mile east of Cholame At that time, Donald Turnipseed, driving a Ford Business Coupe 1950 turned left in front of Dean, and the collision occurred Dean was killed almost immediately and Weutherich was ejected from the Porsche and found next to the driver side of the car at the last Dean rest was found slumped against the door passenger, which triggered a long-standing controversy about who was driving Turnipseed turned counterclockwise and slid to the side of the impact to rest about 38 feet east of the point of impact Porsche Dean traveled about 45 feet from the impact to rest in a north CHP officers leadership attended the scene and took pictures and basic measures.
TV producer asked us to consider the following questions questions on rumors and discussions over the years since the accident.
Was there a decrease of obstruction of vertical visibility on the road prevented Turnipseed see Dean before the accident.
Were there other visibility problems would explain why Turnipseed did not see Dean.
Is Dean brake before impact, or was he trying to drive around Turnipseed.
We were provided with a series of scene photographs taken by CHP officers also received us their reports and sketches Sketches were great for 1955 but did not have accurate scale diagrams of modern times allow an accurate analysis of the speed and positioning of the vehicle as you can see in the scanned images, the information bits of all these documents were to be assembled to allow reconstruction of the scene.
Basic information then had to be supplemented by measures of the scene of the accident on the overall geometry These did not exist, as can be seen the sketch, not only was not wide, but n has not been based measurement protocols and was geometrically inaccurate meant the development of the entire scene diagram as a separate task and integrate evidence information This process was done using the photograph showing the traces skid and final resting Ford using photogrammetry software.
We chose the photograph showing the skid marks, and using VS Hawkeye converted photography at the top level down to the scene.
This image top right was central to the reconstruction of the scene and the development of a specific scene of accident to calculate the speed and 3D animation.
Creating a diagram of the floor has been difficult because of the rawness of the original hand drawn diagram; not to scale and the lack of measures in any basic or standard format triangulation, we measured a result, the geometry of the scene using a total station Nikon and deleted recent improvements in island traffic and turn the bay, leaving the original form of the intersection that the basic geometry, we inserted the picture above ground of the scene.
The challenge was to find the right position on the stage to place the photo The correct position was found with numerous references in old photos that have been at this day unchanged, and moving the photograph turned up that all references were consistent We commisioned accurate 3D models of cars involved and special textures using photos of the scene Cholame, California to get more accurate results.
The speed calculation was done using the conservation of linear momentum Process Vista Dynamic FX graphics solution is used as described below The vehicles were positioned at the maximum commitment and the approach and starting vectors have was simply slid into place.
This analysis was very sensitive to the approach and departure angle changes and update graphics computing, real-time provided by the FX Momentum Vista tool really makes the process much easier than any other method I checked constantly calculating Delta V while adjusting vectors and deceleration rates after the impact I wanted to Delta V to make sense when comparing the calculated Momentum Delta V s base to crush Delta V Delta V s s were very high Ford 31 mph and Porsche 63 mph but when looking at the damage to each vehicle, especially Ford, given 2 1 earth disparity, it is logical that I suggest a range of depending speeds the fact that there is some uncertainty as to the accuracy of the image correction process, and delta V s estimated the crash.
Continuing the analysis of linear dynamics, we adjusted the starting vectors slightly, to create consistency with the delta vs. Speed changes incurred by the damage See photos of the real scene right when the delta vs movement were aligned, we impact velocities in the range of 70 to 75 MPH Dean Porsche and Ford 55-60 for Turnipseed All results are expressed with greater accuracy would not be realistic if the accuracy is considered of the database.
Many readers may wonder how we calculated the rate of deceleration after the impact The answer is simply that we started with a simple approach to estimate the drag factor, then refined by calculating the angle of friction based iteration resulting in post impact values seemed reasonable compared to damage new changes depending on the speed.
When we had the speed values we simply generated 3D animation using 3D Motion real component of Vista Vista FX2 FX2 allows users to simply transfer the results of momentum to animation tracks instantly in five minutes we watched our first animation of the accident.
Using the calculated speeds Mike Kennedy created a state with the 3D animated film of advanced technology, with damage to the live crushing displyed in the animation of the accident.
With the built stage, the analysis, and full animation, the next part was to use the animation results to meet the original questions that were asked National Geographic.
To answer this question, we have placed human models in the Dean Porsche and created an animation slow motion to demonstrate the impact of alignment with the occupants of positions.
The animation slow motion showed above clearly that whoever was driving was struck by the front left corner of the cup 49 Ford The animation also showed that the passenger was pushed sideways out of the door on the passenger side .
The pavement markings indicate the vehicle Dean turned violently against in a clockwise direction which relieved the forces of occupation and why mechanic Rolf, was found outside the vehicle, the driver's side to the final resting vehicle rotated, Rolf was pushed the passenger door, and the vehicle continued to spin at the last rest, so it was found near his ejected position.
At rest James Dean was reported is in the passenger position, with legs well It makes perfect sense Let's face it, after the impact, there was only room for one driver.
An eyewitness was in a 48 Ford truck after Turnipseed 49 Ford in the collision, he swears to this day that Jams Dean was in passenger position to impact with the animation already built, it was easy for me add another vehicle and put a camera animation in the pilot the position of the Ford truck following the 50 yards back to examine her opportunity to see who was driving.
The animation that resulted was a convincing representation of what the witness had a view and for how long these pictures to the right are not really do it justice, but give you an idea of the value can instantly create charts that will support or refute this witness a state.
The biggest question is why did this happen Why Turnipseed turn before Dean.
The view of the wheel Turnipseed has become a very useful tool to determine why it happened, we showed clearly that there was no obstruction of vertical visibility, so why I think it was because the color of the Porsche made little visible in the background color and the floor because Turnipseed was turning left onto another road at highway speeds, so he simply stopped looking directly forward, where Dean was approaching and turned his attention to the road, it was turning.
To explain this, we have created another view of the same animation from the perspective of Turnipseed see left.
This snapshot of the animation in real time precisely puts both vehicles in time before the collision and clearly, Dean was there to see if Turnipseed remained focused before.
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