Saturday, July 26, 2008

Guard Rail

The new code requires a bollard to be designed for 6000lb, 18" above
ground. The load is required to be increased to an unknown amount for
trucks and buses.

What testing is this based on? car weight? speed? Car model crushing
energy absorption?

I found where a tested medium sized truck at 120 mph is stopped with
about a 17000 lb rigid capacity.

So the code vehicle load must be for something traveling at least 60mph.

Bollards, in a parking lot to prevent parking on a sidewalk, is an
example where a lower speed impact might be more reasonable.

I know that there is a liability to have rigid barriers along a highway
due to the potential injuries to the vehicle occupants and so yielding
barriers are part of highway designs. Looking at their post embeddments,
the capacity is no where near to the 6000 lb as specified in the
building code and using the code capacity for poles cantilevered into soil.

Does one need to design for more than the legal speed limit?

Does the impact reduce by the velocity squared?


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