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: