The Traffic Accident Reconstruction Origin -Article-

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CARP 1.04

Metric Accident Reconstruction Program


In 1984 when I first got into the technical side of investigating collisions, computers were not the everyday item they now are. In fact my first computer was a Tandy Pocket Computer with an added memory chip that gave it a whopping 2 K of memory. During that time frame I started writing programs in Basic and later in GW Basic to make my life a little bit easier. These programs were stored on my computer with its limited space and on cassette tapes via a special tape recorder.

In 1991, I decided to take all of the programs I had made over the years and put them under one roof. As a result CARP 1.04 (Computerized Accident Reconstruction Programs) came into being in late 1992.

CARP 1.04 is a DOS based program. As such, it will run on essentially any IBM compatible computer. It has some drawbacks in that the print options have not kept pace with the times.

The user should be prepared to test these options to obtain a usable product. I have found it is best to not even bother with this difficulty. Instead I recommend using the "print screen" capabilities of the keyboard. Another drawback is that if input ridiculous numbers the program may cease to function. If this happens just type [run "menu"] without the brackets and you will end up back at the main menu.

Members of the Royal Canadian Mounted Police are still using this program. Many have asked me when I'm going to convert it for Windows Ô use. My answer is "When a certain very hot spot, I don't intend to visit, freezes over".

Shortcomings notwithstanding, the price is right. It is free. The program does contain a world of formulae including vault, slide to stop, fall, yaw, tip over, roll over, combined speed, accident avoidance, speeds from tachometers and lift caused by wind. Sixteen separate time, velocity and distance formulae, 9 linear momentum formulae, and weight shift for bob-tailed tractors or 3 axle trucks. Some modern day programs do not contain all these features.

Other sections of the program include a routine for determining Delta V from barrier impacts and pole fractures with its basis derived from NTIS pub PB83-112201 and DOT HS-805 742. There are two separate spin to stop programs for determining the post-collision speeds of spinning vehicles and a program to determine the stiffness parameters for vehicles taken from SAE Paper 910119 by Failure Analysis Associates. It also contains a pedestrian/ bicycle program (the metric version of Jerry Eubank's first ped/bike program) which contains 14 formulae.

A group of other routines handle Double Substitution (use of the Conservation of Linear Momentum and the Dissipation of Energy in head-on collisions) and truck rollovers using the Woodrooffe, IPTM and British Columbia formulae. There is even a program for users of the Deluxe Paint 2d animation program used by IPTM in the early 90s for crash animation. Smaller programs such as Limpert's minimum speed to roll after striking a curb, determining line slopes and distances from co-ordinate measurement are some more programs offered.

This program is free. It comes with no warranty of accuracy. In its defense, it has been in use for five years with no reported problems or complaints. The program may be downloaded by clicking on the following link:

J. F. (Jim) Mitchell is an independent accident reconstructionist, author (International Guide Book for Traffic Accident Reconstruction) and computer software programmer who resides in Barrie, Ontario, Canada. Jim retired from the Canadian Military Police in 1990 after 25 years service and then put in three years as an accident reconstructionist with the Special Investigations Unit of the Attorney General of Ontario. Jim has been ACTAR certified since 1994. He can be reached at

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