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Midwest Guardrail System (MGS) Placed Adjacent to a 1V:2H Fill Slope with 6-ft Posts

REPORT NUMBER

TRP-03-320-16

AUTHORS

Austin Haase, Justine Kohtz, Karla Lechtenberg (Polivka), Bob Bielenberg, John Reid, Ronald Faller

PUBLICATION DATE

2016-08-22

ABSTRACT

The Midwest Guardrail System (MGS) has previously been approved for placement on the slope break point of a 1V:2H fill slope if 9-ft (2.7-m) steel posts are used. In order to reduce hardware inventories, states have chosen in some cases to install the standard MGS system at a lateral offset away from the slope break point. Current guidance requires minimum offsets ranging between 1 ft (0.3 m) and 2 ft (0.6 m) from the back of the post to the slope break point for the standard MGS system with 6-ft (1.8-m) long posts, depending on the slope grade. The goal of this research was to evaluate if standard length posts could be placed adjacent to a 1V:2H fill slope while maintaining satisfactory safety performance under the Manual for Assessing Safety Hardware (MASH) TL-3 conditions. The MGS was crash tested with W6x8.5 (W152x12.6) steel posts measuring 72 in. (1,829 mm) long. This system used a 6-in. wide x 12-in. deep x 14½-in. long (152-mm x 305-mm x 368-mm) Southern Yellow Pine wood blockout as well as 12-gauge (2.66-mm) guardrail sections. The design was evaluated using a 5,158-lb (2,340-kg) Dodge Ram 1500 quad-cab pickup truck impacting at 61.6 mph (99.1 km/hr) and 26.3 degrees. The MGS placed adjacent to a 1V:2H fill slope met the MASH safety requirements for the full-scale crash test. Following the full-scale crash testing, recommendations were given regarding the use of standard-length steel posts when MGS systems are installed at the slope break point of a 1V:2H slope.