An investigation of collisions of automotive vehicles with break-away highway sign supports

Abstract

A series of six full-scale crash tests employing an automobile towed into a collision with one support of a two support highway roadside sign was conducted. Fixed base sign supports were struck in two of the tests, and break-away base sign supports were struck in the remaining four tests. High-speed motion picture films were made of each of the crash tests. These films provided a Displacement-Time record of each collision. A piezoelectric accelerometer was installed on the frame of each crash vehicle. The signal from this accelerometer was transmitted to a recording oscillograph, and a trace of the accelerometer behavior was recorded on light sensitive paper. This trace provided an Acceleration-Time record of each collision. Other electronic instrumentation was installed in order to provide Strain-Time information about the collision. A method of successive summation of areas contained by the accelerometer trace is presented which results in a Displacement-Time plot which has been compared with the corresponding data recorded from examination of the high-speed films. Examination and comparison of information from each of the records obtained from the final two tests has led to a time dependent description, or chronology of collision. This description of the collision incident and definition of critical events in the history of the collision provides an original description of the behavior of break-away sign supports subjected to collision by an automotive vehicle.