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This paper presents a method of determining a vehicle crush and equivalent barrier speed using digital photogrammetry. A state-of-the-art documentation technique called close-range photogrammetry allows engineers and accident reconstructionists to create three-dimensional computer models of damaged vehicles utilizing photographs. Utilizing photogrammetric software, engineers can digitize accident scene photographs to create accurate three-dimensional computer models of the vehicles, which can be used to quantify structural damage sustained by the vehicles. Crush deformation can be quantified utilizing this process and the resulting crush dimensions can be input into engineering software to determine a vehicle’s equivalent barrier speed. Knott Laboratory, Inc. has utilized these techniques on cases worldwide including the Princess Diana accident in France [1][2].

Accident scene photographs contain important information that can be useful in determining how accidents happened. However, dimensions are difficult to gather from photographs. The size of an object in the photographs depends on how far away from the camera the object is located. An object in the background looks smaller and will measure smaller than the same size object in the foreground. This phenomenon is called perspective distortion. Photogrammetry was introduced in the late 1800's as a tool to compensate for the perspective distortion and assist in gathering dimensions from photographs. One of the early techniques was to create a transparent miniature of a photograph and place the miniature in the view screen on the camera. The camera was then taken to the scene and matched to the correct position such that the image in the scene matched the image in the view screen.