Determination of the Maximum MGS Mounting Height - Phase I Crash Testing
REPORT NUMBER
TRP-03-255-12
AUTHORS
Cale Stolle, Karla Lechtenberg (Polivka), John Reid, Ronald Faller, Bob Bielenberg, Scott Rosenbaugh, Dean Sicking, Erin Johnson
PUBLICATION DATE
2012-03-09
ABSTRACT
Post-and-rail guardrail systems encounter environmental conditions, such as severe frost heave or erosion, which may drastically affect the post embedment depth and rail mounting height. In addition, guardrail systems may be designed to accommodate future roadway surface overlays. As these scenarios arise, it becomes evident that the rail mounting height tolerances for post-and-rail systems need to be evaluated. Over the years, the recommended minimum top rail mounting height for the MGS was established as 27 3/4 in. (705 mm) based on crash testing with pickup trucks at 25-degree angles and according to the NCHRP Report No. 350 and MASH safety standards. However, no maximum height has been set.
The primary objective of this study was to evaluate the potential for increasing the maximum rail mounting height of the MGS. The research study included two full-scale crash tests with Kia Rio passenger cars, each weighing approximately 2,425 lb (1,100 kg). The first system utilized a 34-in. (864-mm) top rail mounting height and a line post embedment depth of 37 in. (940 mm). The second system utilized a 36-in. (914-mm) top rail mounting height with a line post embedment depth of 35 in. (889 mm). Following the success of the full-scale crash test program, both system heights were found to satisfy MASH TL-3 evaluation criteria for test no. 3-10. Evaluation of these rail heights under pickup truck impacts (test no. 3-11) is necessary before these taller systems can be deemed crashworthy according to MASH.
KEYWORDS
Highway Safety, Crash Test, Roadside Appurtenances, Compliance Test, MASH, MGS, Guardrail, TL-3, Maximum Height, Decreased Embedment Depth