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MGS stiffness transition substituation of W6x15 posts

Question
State IN
Description Text
INDOT is in the process of transitioning to the MGS guardrail.  Currently we are working on the stiffness transition.  We see in report TRP-03-210-10 the last three downstream post (16-18) are W6x15 at 37.5" spacing.  It appears that a couple other states are using six W6x9 posts at 18.75" spacing to substitute for the three W6x15 posts.  Is this noted as acceptable in FAQ or report?  Thank you


Approach Guardrail Transitions (AGTs)



Date November 7, 2016
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The W-to-thrie beam stiffness transition described within report TRP-03-210-10 was developed as the upstream end of the stiffness transition.  Specifically, it addressed the transition from standard W-beam to stiffened thrie beam.  The downstream end of the approach transition (characterized in that report as the stiffened thrie beam region) can consist of any of the crashworthy, thrie beam transitions.  Guidance on how to connect the upstream stiffness transition to other downstream transitions is discussed in chapter 14 of the report (it shows both 37.5" and 18.75" post spacing systems.  Details for connecting the upstream end to one of the more popular 18.75" post spacing systems can be seen on page 167, Figure 96.

If you need further guidance, you can send me the details for the transition you are utilizing or feel free to call.

Date November 10, 2016
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