There is no boundary fence as the area in question is simply bushland and part of the National Park.  There is no track connecting "Cascade Track" fire break and Clarke Road and park visitors should not be attempting to make their own tracks.  It may look as though access is possible as the area is maintained by locals to reduce fire danger and remove invasive species. 
The Ridgewalk will traverse the top of Nicolas Paddocks from "Cascade Track" to One Tree Hill.  This track build should be starting any day.