In this shot,taken from the flood plain,to the eastern side of the fort,the large single tree,is at the south east angle of the Roman fort.I thought at first,that the two angled slopes beneath said tree,could be a Roman road,but after closer inspection,I now doubt that.
see http://pastscape.english-heritage.org.uk/hob.aspx?hob_id=19926
see http://www.roman-britain.org/places/greta_bridge.htm
see http://www.pastscape.org/hob.aspx?hob_id=19926&sort=4&search=all&criteria=greta