Hawaii DOT Dual-Flare Buried-In-Backslope Guardrail End Terminal Part 2 – Reverse Direction Tests

Report Number(s): TRP-03-496b-25

Description: HDOT BIB system was very similar to the as-tested configuration from full-scale testing in the literature conducted in the previous report [1]. Systems tested under criteria established in NCHRP Report No. 350 had a top rail height of 27¾ in.; however, the top rail height of the MGS installation was 31 in. The original modification to the HDOT system for MGS involved increasing the post length from 6 ft to 7 ft throughout the ditch region where the post embedment of a 6-ft long post would be less than 30 in. This design was insufficient for TL-3 impact conditions with a small car and required further modification. An excessively tall system with respect to the impacting small car was identified as the primary issue, and so the height of the top of the rail was maintained at a constant height above the ditch, such that the top of the back side of the post along the centerline was approximately 43⅞ in. between post nos. 8 and 17. Lastly, the rail was horizontal and at a constant height of 1 ft – 11⅜ in. from post nos. 1 to 6. The modified system was evaluated according to MASH TL-3 safety criteria test designation no. 3-37 in full-scale crash test nos. HBIB-6, HBIB-7, HBIB-8, and HBIB-10. Additionally, the anchor block was placed into the backslope, which consisted of native soil fill. Typically, above-grade anchors are used when it is not practical to bury an anchor, such as in soil with significant rock or igneous lava flow. These soil conditions may be significantly stiffer than native soil or MASH strong soil conditions. Thus, additional soil reinforcement was added to the anchor block to simulate conditions in use. The additional reinforcement consisted of a vertical concrete shaft with a 3-ft diameter extending 10 ft deep. Vertical rebar and hoops were used to reinforce the concrete shaft. The additional size and strength of the soil foundation were used to evaluate a practical worst-case anchor block rigidity for testing. The increased reinforcement and foundation strength are not required for typical construction cases.

Test Level: 3

System Type: BIB Guardrail End Terminal

MASH Test Number: 3-37a & 3-37b

Proprietary/Non-proprietary: Non-proprietary

Pass/Fail: Pass

Evaluation: Full-Scale Crash Testing

Sponsor: Hawaii Department of Transportation