That length of road, partly within the boundary of the City of Edinburgh Council and partly within Fife Council, from a point on the north side of the Forth Road Bridge, at the commencement of the unclassified southwards continuation of the A90, 690 metres or thereby south of the southmost abutment of the bridge over the roundabout at which the A90 crosses over the B981 to a point on the south side of the Forth Road Bridge on the A90, 160 metres or thereby north of the northmost face of the overbridge carrying the roundabout on which the A8000 and A904 meet, including those lengths of the slip roads within these points which form part of the A90 and give access to and from the above roundabout on the south side of the Forth Road Bridge, a distance measured along the said length of road approximately 3.15 kilometres.