Logged in as: Public User

MGS Guardrail (Planing Blockouts)

Question
State KS
Description Text

My name is Tom Rhoads and I am a design engineer in Scott King's squad at the Kansas Department of Transportation. I've been assisting Scott with some revisions to our MGS Guardrail Standard Drawings. Throughout our revision process we have been communicating with Ray Schacht at Midwest Machinery Supply and a question has arisen regarding a KDOT Standard Specification indicating the blockouts we use for our guardrail systems should be planed prior to installation (I've attached a copy of the Standard Specification with the area of interest highlighted). Ray indicated once the blockouts are planed the resulting dimensions are 5 ½ inches to 5 5/8 inches by 7 ½ inches to 7 5/8 inches rather than 6 inches by 8 inches. Our question for you is: Is the reduction in the blockout section acceptable for MGS Guardrail installations?

 

Please let us know your thoughts.

 

Keywords
Other Keywords none
Date March 20, 2012
Attachment PDB11ab.pdf
Attachment 2301.pdf


Response
Response

MwRSF has successfully crash tested the MGS in blocked (12" deep) and non-blocked (no offset block but with backup plates) applications. In these testing programs, improved performance was observed when using the offset blocks. TTI later successfully crash tested the MGS with an 8" offset block. As a result of these programs, I would not get too concerned with minor deviations in the block dimensions when comparing full-sawn, rough sawn, and dressed blocks. As a matter of fact, some fabricators start the process with larger wood sizes so that the dressed block actually measures 6"x12" or 6"x8".

 

Previously, manufacturers and other State DOTs also inquired into the MGS block tolerances. Since similar inquiries have been made and responses have already been complied, I am forwarding to you information from the 2007 discussions with the Pooled Fund members states. Hopefully, my response above and the attached information will sufficiently answer your question.

 

Date March 20, 2012
Attachment Response Summary - MGS Implementation - Discussion Topic No. 1 - Standar... (95.7 KB).msg


Contact Us:
130 Whittier Research Center
2200 Vine Street
Lincoln, NE 68583-0853
(402) 472-0965
Email: mwrsf@unl.edu
Disclaimer:
The information contained on the Midwest Roadside Safety Facility (MwRSF) website is subject to change without prior notice. The University of Nebraska and the MwRSF is not responsible or liable, directly or indirectly, for any damage or loss caused or alleged to be caused by or in connection with the use or misuse of or reliance upon any such content, goods, or services available on this site.