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I have a quick question for you. Are you aware of any research or guidance regarding in the field drilled GR W-beam holes? Currently TDOT standard shows a detail moving a post to have a midspan connection transitioning from 27” to 31”. Our office received a question about the shape, oval v. round hole and drilled hole quality compared to punched hole. Unfortunately, not much guidance out there to refer for me. Thanks!

The main concern with creating new holes in the guardrail is poorly formed holes that weaken the rail section due to stress concentrations and corrosion due to exposed/ungalvanized holes.

We typically recommend that care should be taken when field cutting a new post bolt hole such that stress concentrations that may reduce the rail capacity do not arise. Thus, the post bolt hole should be cut smoothly and correspond with typical post bolt hole dimensions. Additionally, we would recommend spray galvanizing the hole to prevent corrosion.

The used of drilling or punching would be acceptable as long as the hole has the correct dimensions and is smooth.

Thanks!