The dynamic deflection of a cable barrier during impact is an important characteristic for many reasons. Compared to semi-rigid W-beam barriers and rigid concrete barriers, cable barriers have much greater deflections, which is the reason that cable barriers typically are more forgiving to theimpacting vehicle's occupants. The elastic behavior of the cables absorbs energy during the impact and thereby reduces the deceleration forces exerted on the vehicle's occupants. However, for the barrier to be safe, adequate space behind the barrier that is clear of hazards must be provided toaccommodate the expected deflections. If deflections exceed the space provided, the errant vehicle could impact rigid objects behind the barrier or worse yet, in median applications cross into opposing traffic on a divided highway. Crashworthiness requirements for cable barriers are contained in National Cooperative Highway Research Program (NCHRP) Report 350 and have recently been updated in the Manual for the Assessment of Safety Hardware (MASH). Under the requirements, dynamic deflections observed in the crash test needs to be reported, but the requirements do not standardize alldesign and installation features of cable barrier systems. Thus, questions arise about performance particularly relative to the different design features and installation configurations for the various proprietary designs that are available. At this time, the crash testing requirements do notfully address the effectiveness of the various high-tension cable systems. The purpose of this study was to investigate the influence of differentcable barrier design features and installation configurations on the dynamic deflection for high-tension cable barrier systems. Two basic design features were examined in the study: cable weaving effects (weaved and parallel systems) and number of cables (three and four-cable systems). The installation configurations investigated included varying end-anchor spacing(installation length) and initial level of cable tension (static tension).
Samenvatting