Understanding Line of Sight
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- Jun 9, 2020
- 2 min read
Updated: Nov 9, 2021
Understanding the Line of Sight and its role in Vehicular Accident Investigations
In many vehicular accidents, the forensic engineer is often called in to make expert opinions as to how the line of sight (ie. how well the driver could see the scenario developing ahead) may have contributed to an accident. Of course, the next determination is to what or who caused this line of sight issue. Contributing factors can be either topographic or man-made. Let’s discuss each. Topographic factors that impede a driver’s line of sight are typically horizontal or vertical. Horizontal translates to a road with left and right turns. A vertical topographic factor results from hills and vallies in the road. Other topographic factors are trees and foliage that may obstruct a driver’s line of sight. Man made factors result from humans making decisions that affect a driver’s line of sight. Examples are the way roads and highways are designed and how road construction work may temporarily obstruct visibility. When roads/highways were constructed many years ago and opposing lanes are divided by a large wall and there is no median lane to pull off, you can imagine the accidents that occur when a vehicle is traveling at speed around a curving road and encounters a disabled vehicle in its path. Other situations occur when construction workers separate traffic with large jersey cement barriers which influence the visibility. Forensic engineers evaluate accidents from a line of sight perspective first by visiting and inspecting the accident scene. Ideally, the engineer will inspect at a time when a similar environment exists as at the time of the accident; lighting and weather can also affect line of sight evaluation. The engineer will work from industry guidelines such as the American Association of State and Highway Transportation Officials (AASHTO) and the Manual for Uniform Traffic Control Devices (MUTCD) to qualify his/her opinions on the human factors involved with designing safe roadways, safe speed (ie. speed limit), and safe working zones.The CED engineer uses his ‘trained eye’ along with an inspection to capture the evidence and provide the building blocks of accident reconstruction.
image below is end of Crumbaugh Road, Georgetown, Ky
looking west to Georgetown, Kentucky
Line of site while stop at end of road
Maintaining an open line of sight
This is the ability to see the center of the driver’s path of travel. When you drive you must have a clear field of vision to gather information and guide a motor vehicle effectively. Good visibility depends on the distance you can see ahead and to the sides. It consists of your line of sight and field of view.
Line of sight is the imaginary line that extends from your eyes to the point of focus. The line of sight can be blocked by a curve, hill, tree branches, buildings, large vehicle, etc. To maintain an open line of sight you will have to make changes in speed and position. When sightlines are blocked, a speed adjustment is needed until the area is visible or the sightline is restored.
Blind intersections, for example are high risk areas and speed/lane position should be adjusted before proceeding into the intersection.
Vol. 99, 1990
Section 6: JOURNAL OF PASSENGER CARS
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