Bollard design 2

I'm not aware of a design code for bollards. However I have had the opportunity to design, install and witness the performance of an assortment of bollards at industrial plants that protect valve stems, environmental monitoring wells, fixed structures, etc. We considered the bollards to be more or less expendable. That is, they would intentionally deflect, or even "uproot", on significant impact to absorb energy & minimize damage to the vehicle.

The description that you give (6" pipe, 4.5 ft. embeddment, 24" diameter encasement) is typical of what we would use for protection from heavy, off-road trucks, front end loaders, bulldozers, truck cranes, etc. If hit by a car, the car would most likely "lose".

For automotive applications we would normally go with something lighter, say a 4" pipe, 3 ft. embeddment, 16" dia. encasement.

However, it's really a judgement call, however since soil properties, pavement around the bollard, etc. are important factors.

Dunno if there's a design code for bollards but one technique I've used in the past is to get the spec for a few bollards from manufacturers.

They will usually quote a "designed to BS____" on them , then you can look up that, and the standards those standards themselves reference.