Category: Crash Reconstruction

For Las Vegas Crash Detail Unit, The Crash Zone Is Ideal

In 1996, the Las Vegas Metro Police Department (LVMPD) was determined to start diagramming crash scenes electronically. Initially, they considered some of the general-purpose diagramming programs until they found The Crash Zone, from The CAD Zone, Inc. of Beaverton, Oregon. Since Crash Zone is specifically for drawing crash scenes, it was the perfect choice to meet LVMPD’s diagramming needs.

The police department’s Fatal Crash Investigation Detail decided to go with The Crash Zone. William Redfairn, the Detail’s lead detective at that time, explained their choice “Crash Zone has a lot of powerful features, yet, you can give it to someone who doesn’t completely understand a CAD program and in a very short time he can start creating diagrams.” Detective Redfairn notes, “it works flawlessly and is very intuitive.”

Ease of use and the ability to quickly create diagrams are critical assets for any software used by the Detail, given their workload. The LVMPD handles between 30,000 and 40,000 traffic accidents a year. Of these, 200 to 300 crashes are investigated by Det. Redfairn’s unit. Nearly 100 of these crashes are fatal crashes.

Crash Zone Valued for Its 3D Capabilities

A major feature that Det. Redfairn values in The Crash Zone is its 3D capabilities. “More than once I have been able to make someone understand why a particular party is at fault when they have been able to view my conclusions in a 3D Crash Zone diagram,” Det. Redfairn said. “Most non-reconstructionists are visual in nature, and 3D gives us the ability to bring the ‘real world’, or as close as we can get to it, to them without them having seen the scene firsthand,” he added.


Detective Redfairn investigates a crash scene.

It’s especially easy to create an accurate 3D model of a scene in Crash Zone because the user starts by creating a 2D diagram from their measurements. Next, they can add any of the 3D symbols from The Crash Zone’s extensive library of vehicles, trees, street lights, signs, road hazards, and more. An easy-to-use 3D Body Poser tool is used to place bodies in the diagram, posed exactly the way they were found at the scene.

Crash Zone also has 50 pre-drawn line types that can be applied to any line, arc, or curve to show 3D fences, guard rails, highway dividers, cones, and more. A number of improvements have been introduced to Crash Zone’s 3D diagramming, including automatic surfacing, 3D light-source shading, and vehicle reflectivity that provide even more realistic views of a crash scene.


Version 10 users have the ability to have both the 2D drawing window and the 3D window open simultaneously. This is especially important for creating drawings from point cloud data that has been captured with a laser scanner, such as the FARO Focus 3D.

Aerial Photos Help Explain Crash Intricacies

 Another feature that the Fatal Crash Investigation Detail is using more frequently is Crash Zone’s ability to import images, including digital photos, aerial and satellite images. Det. Redfairn explains, “We’re starting to import photos, particularly aerial photos. We can plot our evidence with the total station, then later import satellite photos of the crash scene in Crash Zone and tie them into the points collected with the total station.”

A growing advantage is that the LVMPD’s helicopters can come out to a crash scene and shoot overhead views. “What’s important here is that any time in the future other reconstructionists can use these same photos with any mapping they do of the same crash scene,” Det. Redfairn explained. “They can get similar results using their CAD program.”

The ability to import aerial photographs into Crash Zone adds realism to every crash scene diagram and assists in explaining the intricacies of a crash to a judge or jury, according to Det. Redfairn. “The fact that Crash Zone has made this a simple process is a big factor in our use of aerial photography in scaled diagrams,” he added.

Not only can Crash Zone import digital photographs, it also integrates the Microsoft Bing™ Maps. Users can easily obtain recent aerial views from Bing by simply entering an address, intersection, or building name. Click a button to place the aerial photo in the Crash Zone diagram and then use any of the tools to draw on top of the image, place notes, dimensions, and symbols to complete the diagram. Images from Bing can be “georeferenced” so they come into Crash Zone at actual size (1 to1 scale).

Crash Zone has a special feature which makes it easy for the user to align an aerial photo to point data that was shot with a total station. At the scene, the user records points for a few landmarks that will appear in the aerial photo, such as the edge of a street, corners of a building, or a fire hydrant. Once the point data is brought into Crash Zone (either with the Import Data command or the Coordinate Data Table), the first step is to bring in the aerial photo and place it to the side of the points. Then the Align Common Points command can be used to perfectly align the background photo with the actual, measured points.



Redfairn Now a CAD Zone Trainer

William Redfairn retired after 21 years with the Las Vegas Metropolitan Police Department. His last 14 years were with LVMPD’s Accident Investigation section where he was responsible for the investigation of serious injury and fatal traffic collisions. Bill has been recognized as an expert in the fields of accident reconstruction and impaired driving and he has testified numerous times in Nevada courts. He has extensive experience in teaching law enforcement, judges, lawyers, and the general public in the science of vehicle collision investigation and reconstruction.

Redfairn has authored lesson plans and articles in the areas of crash investigation and impaired driving. He also is an authorized CAD Zone trainer and has created an extensive training manual for Crash Zone and Crime Zone users. This manual is available, with the author’s permission, on the CAD Zone website at:

For more information, you can email William Redfairn at:




Bergen County, NJ Fatal Crash Unit Appreciates CZ Point Cloud

For more than 12 years, the Fatal Accident Investigation Unit (FAIU) of the Bergen County, New Jersey, Prosecutor’s Office used The CAD Zone’s Crime Zone software to document crime and crash scenes. When the agency acquired a Leica ScanStation C-10 laser scanner the investigators tried using the point cloud software that was included with the scanner. They found that they could easily scan a scene, but they struggled with creating courtroom-quality diagrams from the resulting point clouds.

Detective Andrew Rich, a 14 year veteran of the Bergen County FAIU (now retired), evaluated The CAD Zone’s CZ Point Cloud software and he quickly determined it was ideal for creating crime and crash scene diagrams from scanned data. He appreciated the many tools included in CZ Point Cloud that are specifically for generating 2D diagrams – which are critical for most investigations. Only CZ Point Cloud makes it easy to work within a point cloud and accurately select the evidence points you need to build both 2D and 3D diagrams.

Use Pre-drawn Symbols For Faster Diagrams

crash zone symbol manager

The Crash Zone Symbol Manager toolbox showing just a few of the pre-drawn symbols.

If you are a Crash Scene Investigator, chances are you have better things to do with your time than spend hours and hours creating drawings of crash scenes. One way to really save on drawing time is to use pre-drawn symbols for commonly found objects.  Instead of trying to draw that vehicle or sign found at the scene, just select the pre-drawn symbol and drag it into place.

General purpose drawing programs may have pre-drawn symbols of furniture or trees, but they will not have many items found at a crash scene, such as vehicles, bodies, signs, or weapons. To get these types of symbols, you need a software program that is specifically for drawing crash scenes.The Crash Zone, crash scene diagramming software published by The CAD Zone, Inc., has thousands of pre-drawn symbols that are ready for you to place in all of your 2D and 3D diagrams. You can easily change any symbol’s rotation, size, and color as you place it in the diagram. Symbols can be placed at an approximate location in the drawing or snapped to an exact data point.

Veteran Instructors Train Crash Zone and Crime Zone Users Around the World

Most investigators who use The Crash Zone or Crime Zone teach themselves how to use the software, taking advantage of the extensive documentation, tutorials, and training movies. However, for those who prefer to have formal training, there are many expert trainers who offer classes on CAD Zone software throughout the US and around the world. Select CAD Zone Training

Many trainers post their upcoming class schedules on the CAD Zone Training Events Calendar. To see information on all the posted classes, visit Select the “Training & Docs” pull down menu and then select “Training Classes.”

On the CAD Zone Training Site, you can select “Events” to display a monthly calendar and a list of upcoming classes. You can also select “Locate a Trainer” (button on the left) to find a trainer near you.

Three CAD Zone trainers are introduced here. To learn more about their experience and classes, refer to the details about each trainer later in the article.

Self Help Training Materials Now Available on WWW.CADZONE.COM

training-menu-fullA large amount of documentation and training materials are available for anyone who wishes to learn how to use Crash Zone or Crime Zone.   Most CAD Zone users take advantage of the User’s Manual, tutorials, and training movies, to help them create their first drawings and to learn to use more advanced features like 3D and animation.

CAD Zone has created some new pages on their website where all the program documentation and training movies are being consolidated. We’ve gathered documentation from many sources and put it all on these pages.