Report Result

TRP-03-496b-25

Mojtaba Atash Bahar, Cody Stolle, Ronald Faller, Joshua Steelman, Karla Lechtenberg (Polivka), James Holloway, Erin Urbank, James Wills Jr.

2025-12-16

The Hawaii Department of Transportation’s (HDOT’s) Buried-in-Backslope system was evaluated to Manual for Assessing Safety Hardware (MASH) Test Level 3 (TL-3) impact conditions in the reverse direction. The system consisted of Midwest Guardrail System (MGS) W-beam railing supported by W6x8.5 steel posts and 8-in. deep recycled plastic blockouts, with a lower W-beam rubrail attached to the post. The terminal had a 13:1 flare (4.4 degrees) from a tangent roadside system between post nos. 29 and 10, and a second 7.4:1 flare (6.8 degrees) between post no. 10 and the upstream anchor block. The system passed through a V-ditch with a 120-in. wide, 6H:1V foreslope and a 2:1 backslope. The dual-flare system was evaluated in the reverse-direction configuration in test nos. HBIB-6 through HBIB-8 and HBIB-10. During test no. HBIB-6, conducted according to MASH test designation 3-37a, a 2270P pickup truck impacted the system 197.6 in. upstream from the centerline splice between post nos. 29 and 30, and the barrier system effectively contained and redirected the vehicle. In test no. HBIB-7, conducted according to MASH test designation 3-37b, an 1100C passenger car impacted the system 82½ in. upstream from the centerline splice between post nos. 29 and 30, and the barrier system effectively contained and redirected the vehicle. During test no. HBIB-8, conducted according to MASH test designation 3-37a, a 2270P pickup truck impacted the barrier 67.0 in. upstream from the upstream end of the concrete anchor block, and the barrier system effectively contained and redirected the vehicle and test no. HBIB-8. During test no. HBIB-10, conducted according to MASH test designation 3-37b, a 1100C passenger car impacted the barrier 41.5 in. upstream from the upstream end of the anchor block, and the barrier system effectively contained and redirected the 1100C vehicle. Test nos. HBIB-6, HBIB-7, HBIB-8, and HBIB-10 were deemed acceptable according to the MASH safety performance criteria for test designation nos. 3-37a and 3-37b, therefore, the HDOT Buried-in-Backslope system was deemed acceptable according to MASH evaluation criteria. HDOT desired to have an option for both dual-flare and single-flare embodiments of the HBIB design. Single-flare systems may be used in locations where the backslope is located close to the roadway or in some reverse-direction applications. The single-flare configuration was evaluated in the reverse-direction configuration in test no. HBIB-9, conducted according to MASH test designation 3-37a, in which a 2270P pickup truck impacted the barrier 68.5 in. upstream from the upstream end of the concrete anchor. After exiting the system, the vehicle rolled over, coming to rest on its roof, and occupant compartment deformation values exceeded MASH limits at the A-pillar, B-pillar, and roof. Therefore, test no. HBIB-9 was determined to be unsuccessful according to MASH safety performance criteria for test designation no. 3-37a. In conclusion, only the dual-flare HBIB system was determined to be crashworthy according to MASH TL-3 impact conditions.

Highway Safety, Crash Test, Roadside Appurtenances, Compliance Test, MASH, Buried in Backslope, Guardrail, End Terminal, Flare

TRP-03-496b-25.pdf