Evaluation of the MGS with Half Post Spacing and 7-ft Post Adjacent to Slope

Report Number(s): TRP-03-452-24

Description: The test installation for the modified MGS adjacent to a 2H:1V slope consisted of a 175-ft long modified MGS that utilized 12-gauge W-beam guardrail supported by 40 posts. The modified MGS was installed on level terrain for 50 ft on each end of the system, while the middle of the barrier was installed adjacent to a 5-ft deep by 75-ft long 2H:1V slope. The slope started at the centerline of the post and extended 10 ft behind the post. Post nos. 3 through 8 and 32 through 38 were ASTM A992 W6x8.5 steel posts that measured 72-in. long and were spaced 75 in. apart with an embedment depth of 40 in. Post nos. 9 through 31 were ASTM A992 W6x8.5 steel posts that measured 84 in. long, were spaced 37½ in. apart with W14x22 blockouts, and had an embedment depth of 52 in. The posts were placed in a compacted, coarse, crushed limestone material with a strength that satisfied MASH 2016 criteria. Post nos. 3 through 38 used 6-in. x 12- in. x 14¼-in. wood blockouts to offset the rail away from the front face of the steel posts. The upstream and downstream ends of the guardrail installation were configured with a trailing-end anchorage system. The guardrail anchorage system was utilized to simulate the strength of other crashworthy end terminals. The anchorage system consisted of timber posts, foundation tubes, anchor cables, bearing plates, rail brackets, and channel struts, which closely resembled the hardware used in the Modified Breakaway Cable Terminal (BCT) system and is now part of a crashworthy, downstream trailing end terminal [6-8].

Test Level: 3

MASH Test Number: 3-11, 3-10

Proprietary/Non-proprietary: Non-proprietary

Pass/Fail: Pass

Evaluation: Full-Scale Crash Testing

Sponsor: Wisconsin Department of Transportation