The Traffic Accident Reconstruction Origin -ARnews-

Princess Diana's Crash

Brian G. McHenry ([email protected])
Mon, 7 Sep 1998 11:57:01 -0400 (EDT)

This is in response to questions about our analysis for 48 Hours broadcast
Aug 31 1998 (It also was broadcast on June 30 1998).

We were provided the police diagram, measurements of the tunnel, etc.
We did a thorough analysis based on the information provided.
We tested our analysis with our computer simulation programs, including
m-hvosm (McHenry Highway Vehicle Object Simulation Model) which is based
on Newtonian physics, to simulate the entire maneuver including the
pre-impact maneuver, the impact with the curb, the impact with the
pillar and the subsequent rotation to rest. (FYI, the m-hvosm was
created under a government contract by Raymond R. McHenry (my father)
and it was used by him to uniquely test validity by designing a 360
degree rollover automobile stunt, the Astro-Spiral jump, which can be
seen in the James Bond movie "Man with the Golden Gun")

In response to some other comments in the prior posting:

After interaction with the Mercedes, the Uno had adequate time for
perception, reaction and to come to a complete stop with only moderate
braking. (Aside from the Mercedes tire marks, there were no other tire
marks reported by police at the scene which limits the maximum speed of
the Uno)

(Also note that the glass breakage and therefore interaction of the
vehicles had to occur prior to the entrance to the tunnel since glass
and debris found in the tunnel had to travel to rest, after breaking,
from an approx. 2 foot elevation starting at a speed of between 40
and 70 mph)

Speed, alcohol and probably some form of road rage caused a loss of
control of the automobile.

Impact speed-change, the lack of restraint use by the occupants and
the lack of a guardrail or other attenuating device in the tunnel
contributed to the fatalities.

You can be assured that several complete animations from many different
perspective views were provided to 48 Hours. The 48 Hours editors chose
what to present. (If you saw the June 1998 48 Hours presentation you
would have seen more views of the reconstruction/animations).

Apparently you did not see some of the animations created by others which
were broadcast on CNN and other networks. One had the Uno changing speed
and the Mercedes up on one wheel during their interaction and then the
Uno somehow passing the Mercedes by running up on the walkway as the
Mercedes crashed into the pillar. Another had the Mercedes flip (rollover)
subsequent to the impact with the post.

It is obvious that these other animations were based on non-Newtonian
analysis procedures.

Background information on accident investigation, reconstruction and
computer simulation models can be found on our web site at:
http://www.mchenrysoftware.com

Brian G. McHenry
[email protected]

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