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The Best Tool for Accident Investigation Since the Tape Measure
by Joseph E. Badger
First a quick definition — CAD: Computer-Aided Drafting. Or Computer Assisted Drawing. Even Colossal Accident Diagram. Call it what you will, even the police investigator, with minimal drawing ability, one who can't draw a straight line without a ruler, can create great scale drawings with a CAD program and a computer. CAD systems are to the draftsmen and diagramers as the word processor is to the writer. Granted, many individual officers can't rush out and buy a personal computer, color monitor and CAD program just to draw accident diagrams. However, most police departments already have a computer, color monitor, and printer. Many agencies have more than one and, in some cases, they've even relegated an old IBM to a store room someplace and it's just sitting there collecting dust.
As far as price, CAD programs run anywhere from $30,000 and up for vast, complicated, multi-faceted programs that only major industry or the federal government can afford. And there are those developed for architectural and complex engineering disciplines down to simple "paint" programs. The hardware can be quite expensive also, depending on the peripheral devices (mice, plotters, and printers), screen resolution, and sophistication of the processor (primarily speed and size).
Probably the best known CAD software is AutoCAD by Autodesk, Inc., of Sausalito, CA. It costs "around" $3,000. Others frequently considered are Drafix CAD Ultra ($395) by Foresight Resources, Kansas City, MO; GenericCADD ($300) by Generic Software, Bothell, WA; DesignCAD ($299 to $399) by American Small Business Computer, Inc., Pryor, OK; or VersaCAD/386 ($3,495), by Versacad Corp., Huntington Beach, CA.
However, to my knowledge, there is only one CAD program designed specifically for motor vehicle accident investigators. The backbone of an accident reconstruction is a scale diagram of the accident site. In my opinion, the best program available today for police officers and those involved with accident investigation and reconstruction is EDCAD ($750), developed by Engineering Dynamics Corp. (EDC), of Beaverton, Oregon.
Why? For one reason, it's easy to use, "User Friendly," as they say. I mastered the program without any special training and if I, the original computer illiterate, can produce scale drawings with it, anybody can.
It can take the drudery and travail out of doing scale drawings.
Unfortunately, many police agencies don't put a lot of time or effort into accident investigation. The brass may not want you spending a lot of time on accident investigation; some of the old timers feel it's just a job they do for the insurance companies. However, most of the progressive police departments have specially trained units or teams of specialists whose primary function is to investigate and/or reconstruct fatality or serious injury accidents. It is to those agencies and officers that this article is directed.
Basically, CAD programs let the user draw lines and arcs in different colors and line widths. Many have symbol libraries that come with the program or that are optional extras. Most allow you to copy or move something from one place to another on the screen and automatically erase the last entity created. They also have an "Oops" option, a single key stroke, should you accidentally erase something. A quality CAD program will permit the operator to zoom in on a drawing for fine detail work and to zoom out for a bird's eye view of the entire drawing.
EDCAD does all that and more. But the point I must stress is that it was designed for the accident investigator. It can take the drudgery and travail out of doing scale drawings.
First, the EDCAD developers have included an accident site template with several generic roadways and intersections with typical lane widths. There are two-, three- and four-lane roads plus intersection combinations. For instance, Figure 1 represents a two-lane road intersection of four-lane undivided highway.
Figure 1: Example of an EDCAD pre-drawn site. The computer filename is 2-4.SIT, signifying a two-lane road intersecting a four-lane road.
Pre-Drawn Shapes
Also included in the program is a library of 29 symbols. Figure 2 shows a partial list including a car, pickup truck, van, north arrow, semi-tractor / trailer, bush, and railroad warning sign. Each symbol may be enlarged or reduced in size, rotated at an angle, and positioned anywhere on the screen.
Figure 2: Examples of shapes or symbols included with EDCAD. Each shape may be enlarged, reduced or rotated to any angle.
Once you become accustomed to EDCAD, you'll want to create your own shapes to expand the program's capabilities. In Figure 3, you'll see some of my own shapes from a Dodge Daytona T-top to a VW bug. I've also created a couple of motor cycles, with or without riders (Figure 4).
Figure 3: The user may wish to create shapes. These were created by the author.
Figure 4: More examples of the author's shapes. Your library of symbols and shapes is limited only by your imagination.
After-accident situation maps or diagrams can be as detailed as you choose to make them. Figure 5 depicts a parking lot in Anytown, USA. As you can see, a car comes into the lot a bit on the fast side, squalls around a corner, and clips the back of a parked car.
Figure 5: Sample after-accident situation diagram. The scale drawing may be as detailed as you wish.
There is an on-line HELP file that gives detailed information about EDCAD commands, options, data entry formats, and errors. An OPTIONS menu lets you choose from among eight fonts for text (including the normal and italicized Roman, Ivy, Script, and the more traditional Helvetica), sixteen colors, seven line types, and an infinite number of line widths.
Another benefit of EDCAD is its ability to show and print diagrams at different scales. You can create one drawing and print it to the common scales of 1" = 10" or 1" = 20" or virtually any scale that fits your needs.
Eight layers of overlays within EDCAD allow the user to draw a site (with roadways, sidewalks, trees, and shrubs) on one layer, the pre-collision position of vehicles on another, and the final rest position on yet another level. All layers can then be printed as one drawing or as separate facets. If you're working with a color plotter, you can place items of like colors on its own layer.
There is a DISTANCE feature that has several applications. One is checking distances between objects. You merely place the cursor on the first object, then on the second, and a message at the bottom of the screen will display the exact distance between the two points, accurate within one hundredth of a foot.
Frequent Accident Locations
If your jurisdiction is characteristic of most, there are certain locations where accidents are prevalent. Each time an officer works an accident at one of those frequent accident locations, a new drawing must be made for the accident report. An attorney might be able to call the accuracy of a particular drawing into question if it was compared to other diagrams of the same location. However, with a CAD program, the location of frequent accidents, usually an intersection, can be drawn once, then saved within the program.
As accidents occur, all the officer need do is recall the location diagram, put the physical evidence in place (tiremarks, debris, vehicles, etc.), and print out the completed scene in minutes. The investigator may then save that new drawing in its own file and the original site diagram is still available for the next accident.
Why a Scale Drawing Anyway?
Often, the quality of a traffic accident investigation is in direct proportion to the seriousness of the event. "Fenderbenders" usually get a quick going-over and fatality accidents customarily dictate more attention to detail. However, the investigator cannot always know when a specific accident will end up in civil court, often years after the occurrence. I recommend treating almost all traffic accidents as though a lawsuit will be filed.
The officer at the scene may feel, at the time, that the accident scenario is cut and dried, and even a couple eyeball witnesses will testify to what happened, the location of vehicles and so on. The accident report is completed quickly so the road can be cleared and he or she can get on to the next assignment.
From there, you can almost take it to the bank. Two years down the road, you're called in to testify. The photographs were either lost, or they didn't turn out, the witnesses cannot be found, and an issue comes up, such as speed of one of the vehicles. An element of the accident must be reconstructed.
While you're at an accident scene, and the vehicles are at final rest and the road is blocked, take sufficient measurements, especially of tire marks, gouges, concentration of debris, and location of vehicles. Keep in mind the drawing will later be done with a CAD program and start with a reference point. This could be the apex intercept of two roadways or some fixed object, such as a utility pole or concrete abutment. Measure not only the length of skidmarks, but where they start and stop in relation to the reference point. Then, once the scale drawing has been completed, a reconstruction can possibly be conducted two or three years later.
At any time during the creation of a diagram, the on-line HELP file "contains the equivalent of nearly 100 typewritten pages of information about EDCAD commands, options, data entry formats, and errors," according to the EDCAD manual. For quality accident diagrams, you no longer have to use the little rubber stamp cars and traffic templates, nor will you need to use the edge of your campaign hat or an LP record to draw curves. Use a CAD program and let the computer do the work.
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