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Thrie Beam lapping at end shoe connection

State WI
Description Text Is their a correct way to lap nested thrie beam at the end shoe connection. I have seen different variations. 
  • Approach Guardrail Transitions
  • Guardrail
Other Keywords End shoe attachment
Date April 23, 2018


I don’t know if I would call it “supposed to be lapped”. Rather there may be a benefit to lapping things a certain way for nested guardrail connected to an end shoe.


Typically, we have lapped our end shoe connections with both plies of the nested rail on the outside of the end shoe. This has worked fine structurally, but does allow slightly increased vehicle snag potential on the rail when impacted in the reverse direction.


An alternative is to sandwich the end shoe between the nested thrie sections as shown below. This has the benefit of reduced snag potential and loads the splice bolts in double shear rather than single shear. Thus, this may the best configuration from an engineering perspective.

Date April 24, 2018
Attachment thrielap1.jpg
Attachment thrielap2.jpg
Attachment thrielap3.jpg

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