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Old Minnesota Bullnose System Steel Post Limits

Question
State MN
Description Text

Based on the testing of the NCHRP 230 tested Minnesota Bullnose barrier, at what point do you recommend that steel posts can be safely used in the system?




Bullnose Systems


Date June 25, 2004
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Response
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Looking at the old test report, in the 4,500 lbs sedan test,  six posts on one side of the system plus the center post where fractured. In addition, 3 posts were fractured on the other side of the system. It was also noted that the sedan was not completely stopped by the system, but instead had a low level impact with the concrete piers in the center of the system.

 

Based on the posts broken in the system and the fact that the car stopped a bit prematurely due to impact with the bridge pier, we are recommending that steel posts not be used for the frist 13 posts in the system. That would mean that the center post and the first six posts on each side of the system need to be wood posts as specified in the tested design.


Date June 28, 2004
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