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I have been asked to review a sign design. I believe that TTI tested the design to NCHRP 350. But they only ran the truck tests. They way I see the testing and what TxDOT has in their drawings, I'm concerned about the sand bags and 4" on a 5ft chord issue.
I have indicated that the drawings may not meet the MASH requirements because they would likely need a small car test.
If you could review this it would help.
|Date||January 4, 2016|
|Attachment||wz-3 Exit sign.pdf|
|Attachment||RE_ Temporary Sign Support.pdf|
The sign support from test 453360-3 is documented in TTI Report No. 5388-1F.
A temporary, skid-mounted temporary sign with a mounting height of 7 ft that was recently tested to MASH with a small car at the Texas A&M Transportation Institute had an unsuccessful performance due to excessive occupant impact velocity (test no. 467824-2 in report 0-6782-2). However, with some modifications to the breakaway features of the system, the system performed satisfactorily with the both the small car (test 467824-4) and pickup truck (test 467824-3). Also, additional guidelines were developed based on wind loads to design temporary sign systems to select sign supports based on the sign size desired.
This MASH testing indicated that the breakaway mechanism of sign supports is critical to a successful small car performance. As such, it unknown how the small car would interact with the particular sign support you are inquiring about and how that system would break away. An alternative would be to utilize the skid-mounted, temporary sign support evaluated to MASH safety performance criteria and the guidelines based on wind loads (TTI Report No. 0-6782-2).
|Date||January 11, 2016|
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