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75 CHAPTER 14 Generic End Terminal Guidance This chapter specifies the rationale for repair criteria for generic end terminals. The intent was to specify guidance which was applicable to all end terminal types (except as noted). Manufacturers of proprietary end terminal systems may recommend additional repair thresholds specific to an individual terminal. Note that this guidance was based solely on engineering judgment; no finite element simulations or pendulum tests evaluating these end terminal damage modes were conducted. The guidelines which follow were based on an Ohio Department of Transportation Energy Absorbing End Terminal Maintenance Checklist (Focke, 2007). 14.1 Generic End Terminal Damage Modes Damaged end post. The first post of a w-beam end termi- nal provides crucial anchorage of the w-beam section to the Figure 64. Wood post with cross-grain cracking ground, typically through the use of a swaged anchor cable. If (photo: courtesy of South Dakota DOT). the first post is broken or missing, the redirective capabilities of the barrier downstream of the end terminal are likely com- of missing or incorrectly aligned cable bracket bearing plates promised, depending on the proximity of the second impact are shown in Figure 65. A slack anchor cable has been defined to the damaged terminal. To be conservative, the research team as a cable that can be pushed down by hand by more than recommends the replacement of any terminal end post which 1 inch based on the Ohio DOT end terminal checklist. is sufficiently damaged that it cannot fulfill its functions. Posts in this category include broken, severely cracked, missing, or Improper Stub Height. In some guardrail end terminal rotted terminal end posts. An example is shown in Figure 64. installations, the steel tubes or hinged posts may be too high The relative priority assigned to this damage type is high due to for proper activation of the breakaway mechanism of the end the likelihood of a loss of redirective capability of the barrier. terminal (Figure 66). Stub heights above the ground level should not exceed 4 inches. Stub heights have been observed Missing/slack anchor cable. Similar to the terminal end to exceed this limit due both to incorrect installation and, in post, the anchor cable allows the w-beam section to develop some areas, due to frost heave. A medium-priority repair has adequate tension to redirect the vehicle. As with a broken end been assigned to this damage mode because an incorrect stub post, a missing anchor cable will impair the capability of the height will not cause the end terminal to fail but nevertheless barrier to redirect an impacting vehicle. Based on this ratio- may lead to small vehicle snagging or less than optimal oper- nale, a missing anchor cable was assigned a high-priority ation of the end terminal. repair. A loose anchor cable or cable bracket was assigned a medium priority as the w-beam may still be able to develop a Missing/Failed Lag Bolts on Impact head. Energy ab- large portion of tension through the anchor cable. Examples sorbing terminals such as the ET-2000 and SKT-350 use an im-