Drive way Bollard

[6 pot]

If I have put this in the wrong place please move it to the correct spot
I would like to fit a bollard in the middle of my drive as added protection
The one I like in the details says Breaking resistance: 110,000J
Could someone please put this into terms I can understand? ie a VW polo hitting it at 10 MPH or a 7.5 tonne truck hitting it at 30 MPH I have asked the supplier but they just said there are a lot of different things that would affect its impact.
If the bollard will not stop a slow moving car it is not what i want
Thanks for looking

[Jimbo.]

6 pot said:

If I have put this in the wrong place please move it to the correct spot
I would like to fit a bollard in the middle of my drive as added protection
The one I like in the details says Breaking resistance: 110,000J
Could someone please put this into terms I can understand? ie a VW polo hitting it at 10 MPH or a 7.5 tonne truck hitting it at 30 MPH I have asked the supplier but they just said there are a lot of different things that would affect its impact.
If the bollard will not stop a slow moving car it is not what i want
Thanks for looking

A 1500Kg car moving at 10mph has approx. 15000J of kinetic energy.

[6 pot]

Thanks so 110000j should be enough ram raid protection
I will get it fitted

[Grrbang]

Kinetic energy (Joules) is 1/2 x mass (kg) x velocity^2 (m/s).

110,000J is 13.5m/s for a 1200kg vehicle, or 30mph.

For a 7500kg vehicle, it would be 12mph.

While it is easy to design a steel column with enough strength to completely destroy a car, providing sufficient foundations is another matter.

Breaking resistance isn’t a normal engineering term unless there is a standard defining it. Joules also aren’t a standard unit for defining strength. I suspect they presented as 110,000J because big numbers must be good!

I suspect the number is meaningless except for comparative purposes. If I were buying a bollard, I would consider it a deterrent and nothing more. Convenience features such as remote retraction would be of more interest.

[PurpleFox]

From the above calculations, it would seem a fairly substantial bollard - but what are you fixing it to and how are you fixing it? Surely that is going to be the weakest point (by far).

A bollard to stop a car at 30mph would have to be buried quite deep into the ground.

[cml24]

PurpleFox said:

From the above calculations, it would seem a fairly substantial bollard - but what are you fixing it to and how are you fixing it? Surely that is going to be the weakest point (by far).

A bollard to stop a car at 30mph would have to be buried quite deep into the ground.

I have the results on some tests we had done at work. They used an armoured personal carrier to hit the bollards. Some of the bollards have a foundation that is 1.4m x 1.4m by 1m deep. Thats only for a 90mm diameter bollard. I would agree that the fixing/foundation is likely to be the weak point.