The 'burrowing' was provided by two reverse curve alignments with the 'bores' separated by a dividing wall with refuge manways, besides those provided in the main support walls. Although generally referred to as the "Graving Dock Tunnels", technically the facility was in fact a long skew rail underbridge over which some 14 sidings passed between Cadoxton Low Level Junction and Barry Docks signal box. The structure was radically altered to provide the new Barry docks area southerly town bypass road and now named Ffordd-y-mileniwm, one half of the 'bore' being backfilled and the other, capped by a skew road overbridge which now provides a direct road link from Cadoxton to Barry Island. Just one freight railtrack survives here and links the Barry-Cardiff main line with No.2 dock.