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Wisconsin DOT had a question regarding the Missouri single-slope approach guardrail transition developed at MwRSF (TRP-03-47-95). In that report, the thrie beam end shoe is anchored to the single-slope with "self-drilling" RedHead anchors and 7/8" A325 bolts. Wisconsin could not find similar anchors available from RedHead, and asked what their potential alternatives would be.

Here is a quick summary of the alternatives for this problem.

The original single slope approach guardrail transition used 7/8" diameter A325 bolts with "self-drilling" Redhead anchors. These anchors had a listed capacity of 20.5 kips in pullout/tension and 24.32 kips in shear. The higher grade bolt was required to address bending of the bolt.

The issue that arises is that this anchorage is no longer made. Thus, we looked through the available alternatives.

1. There are not currently available drop-ins or wedge bolt type anchors that are 7/8" diameter or are any made in high grade steel. I can get 3/4" diameter anchors the meet the 20.5 and 24.32 kip anchor loads, but the bolts will not handle the same bending loads as those in the original design.
2. There are 7/8" diameter mechanical stud anchors available, but neither is available in high grade steel. Thus, they may not be strong enough for the bending loads.  Also, studs are not as easy to use as the original anchors and there is some snag potential on the heads.
3. Bolting through is a potential option.
4. Another option for attachment would be epoxied threaded rod. 7/8" diameter, B7 threaded rod would be stronger than the bolts in the original design and could be epoxied into the concrete. Based on a review of the available epoxies from Powers Fasteners and RedHead, it appears that they would require approximately 7 7/8" of embedment. This may be difficult to embed based on the width of the barrier. Also, there would be potential for snag on the threaded rod similar to the bolt through option.
5. Anchors could also be cast into the barrier as long as they had similar or greater capacity to the 7/8" A325 bolts used in the original design.

The ¾" anchors may potentially be sufficient, but we could not guarantee the same capacity as the originally tested system. Thus, they would require additional research or testing.