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We have a couple of quick questions for you regarding minimum wooden post strengths/densities needed for guardrail. This subject area isn't my strong suit, but I have been asked to find out more info...so here are is a brief summary of the issue:

Currently NDOR specifies that, wooden posts must meet a minimum of 1600 psi.  Suppliers are having extreme difficulty providing this grade of wooden posts, and they want to understand why we require a grade so much higher than AASHTO standards.  Some folks assert that the 1600 psi post is necessary to retain expected performance, in crashes when the ground is frozen, others think that requiring this grade of post may be unnecessary, expensive and  leads to the primary use of steel posts.   Replacement posts are also currently required to meet this specification.   What are your thoughts...is it necessary to require 1600 psi for the system to perform as designed?  Do you know generally what some of the other MWRSF states require?

Recall that the MwRSF conducted a study of the strength of guardrail posts sampled from field sites across the state. This study, funded by NDOR, involved removing and grading more than 600 guardrail posts. A stratified random sampling technique was used to select test specimens from this group of posts and approximately 100 posts were tested, either statically or dynamically. Based upon this research, we concluded that Grades 2, 2D, 1, 1D, and DS-65 were all adequate for use as guardrail posts. At the conclusion of this process, we recommended that, in the interest of assuring the quality guardrail posts, NDOR should require Grade 1 or better Southern Yellow Pine (SYP) posts (SYP is the most common type of wood used for guardrail posts East of the Rockies). Note that this recommendation is consistent with AASHTO guidelines and assures that practically all wood posts would be Grade 2 or better which we found to be the actual minimum strength.

At the time that the MwRSF made this recommendation, NDOR chose not to relax its specification, but instead maintained the pre-existing requirement that all wood posts be SYP DS-65 or better (this is a very high grade that is very costly). I suspect that the decision to retain the requirement for DS-65 was, at least in-part, a reflection of NDOR dissatisfaction with the wood industry regarding its years long practice of supplying mill run quality SYP and certifying it as DS-65. Never-the-less, in response to the NDOR decision, the MwRSF did not include the recommendation for adopting Grade 1 SYP. Instead, as you can see the attached report remains silent on the issue of the standard for new wood purchases.

We stand by our original recommendation that NDOR adopt a wood post specification that requires Grade 1 or better SYP. We could even support adopting a requirement for Grade 2 or better SYP, provided this change came with a review and possible upgrading of wood post inspection procedures.