This project developed a unique class of guardrail terminal retrofits suitable for secondary (Figure 1). These new terminal structures do not penetrate errant vehicles but bend upon impact and form sufficient frontal area to mitigate vehicle spearing. Made of mild steel, these terminals curve away from the direction of traffic flow, have variable depth corrugations, have an increasing flare toward the impact end, and have breakaway supporting posts. Lowspeed crash tests were performed on half-scale terminal models in which the test car, traveling at about 5 mph and without bumper shock absorbers, impacted the models head-on. These results showed that the plastic failure zones occurred further toward the tip of impact than for static loading, or at about the two-thirds point from the fixed end.
The ideal final design of a guardrail will incorporate the following features.
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A retrofit that is low cost, simply fabricated, and easily installed.
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A retrofit that buckles plastically near mid-length.
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A retrofit that helps redirect impacting vehicles and minimizes fatalities for their occupants.
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A retrofit that limits the ridedown deceleration of the impacting vehicle to 15 g.
The principal investigator, with Duke University Office of Science and Technology, is processing a patent on this product and is looking for potential product developers who would be granted a license to manufacture and commercialize the product. The final report is available from the National Technical Information Service (NTIS #PB 98-139058).
The final report for this IDEA project can be found at:
https://www.trb.org/studies/idea/finalreports/highway/NCHRP034_Final_Report.pdf
