Design Of Cable-To-Post Attachments For Use In A Non-Proprietary, High-Tension, Cable Median Barrier
Ryan Bateman, Ronald Faller, Bob Bielenberg, Dean Sicking, John Reid, Cody Stolle, Karla Lechtenberg, Scott Rosenbaugh
Cable median barriers are widely used across the country to prevent cross-median crashes. Several years ago, the Midwest States Pooled Fund Program contracted with the Midwest Roadside Safety Facility (MwRSF) to develop a new, non-proprietary, high-tension, 4-cable median barrier. In the Fall of 2011 and following two failed full-scale vehicle crash tests on prototype barrier systems, it was determined that design modifications were necessary to improve barrier performance. In addition, members of the Midwest States Pooled Fund Program desired to redirect the development effort. Both of the barrier system failures which prompted the re-design effort could be partially attributed to the manner in which the cables were attached to the posts. Therefore, the cable-to-post attachments at all four cable heights were to be re-designed. The first step in this effort was to determine the minimum design loads associated with horizontal and vertical curves as a function of post spacing. Once the design loads were known, target capacities for the lateral and vertical cable release out of the cable-to-post attachments were determined. The target vertical and lateral cable release capacities for the lower three cables were 225 lb (1.00 kN) and 6.00 kips (26.7 kN), respectively. The top cable-to-post attachment had a target range of 100 to 200 lb (445 to 890 N) for both the lateral and vertical cable release capacities. MwRSF performed seventy dynamic component tests, forty-five static component tests, and one bogie impact test on prototype cable-to-post attachments. Finally, a cable-to-post attachment, consisting of a bolted tabbed bracket, was recommended for use with the lower three cables and provided lateral and vertical cable release capacities of 6.10 kips (27.1 kN) and 346 lb (1.54 kN), respectively. Further, a top cable-to-post attachment, consisting of a straight brass rod with bent ends, was recommended for placement in a notch and provided a vertical and lateral cable release capacity of approximately 175 lb (778 N).
High-Tension, Median, Cable Barrier, Cable Hardware, Crash Test, Highway Safety, Roadside Appurtenances