This report included an analysis of 110 accidents involving breakaway-cableterminal (BCT) end treatments and 36 accidents involving median-breakaway-cableterminal (MBCT) end treatments as used in Kentucky. The primary data base consisted of Kentucky accident records for the years 1980-87; with a few accidents that were identified before 1980. An attempt was made to document each accident with a police report, photographs, and a maintenance repair form.
Results revealed that the breakaway-cable-terminal end treatment performed properly in 73 percent of the accidents when all three configurations of end treatments were combined (simple curve, parabolic flare, and straight). Proper performance was defined as the wooden posts breaking away as designed or the guardrail redirecting the vehicle. Only 10 impacts were documented for small cars and the BCT performed improperly in four of those accidents. Evaluation of the BCT end treatment indicates that it may be used where geometries permit. Where those geometries are not present, the turned-down end treatment proposed in a previous report should be used.
The MBCT end treatment performed properly in 63 percent of the accidents. Problems related to stiffness of the end treatment were most apparent when impact angles were shallow. A recommendation was made to contour grade gore areas where possible and to install a crash cushion where the need for a barrier cannot be eliminated. For MBCT installations at median piers and median width of 20 feet or less, crash cushions were also recommended. A turned-down design was proposed for consideration at median piers where median width was greater than 20 feet.
Digital Object Identifier
Pigman, Jerry G. and Agent, Kenneth R., "Performance Evaluation of Breakaway-Cable-Terminal End Treatments" (1987). Kentucky Transportation Center Research Report. 745.