Most of the wheelies etc do happen on a public road and the Police do have a good presence there during peak hours. It's a case that they cannot be there 24/7 and sometime get their timing and shifts out off sync with peak hours.
You can see how it lies in relation to the public roads here:
http://maps.google.co.uk/?ie=UTF8&hq=&h ... 7&t=h&z=18