GWR Abernant Tunnel

Opened : 1853

Closed : 1967

Engineering code : MER

Abernant tunnel, also known as the Aberdare or Merthyr tunnel was built to carry the GWR from Merthyr to Neath via Hirwaun. Located beneath Mynydd Gethin, this 2497 yds tunnel is one of the longest in the area. The tunnel istelf was built single track, although the eastern approach was up to 4 track at the Cyrfartha Junction (about 1/2 mile away.) The Cyrfartha Junction allowed GWR traffic between Neath an Merthyr High Street to cross GWR/TVR joint traffic from Quaker's Yard to Dowlais. The route was abandoned in 1967 and the tunnel mouth bricked up. In 1998 the walls were removed and fencing put in their place.The tunnel is lined in part with stone blocks, these belong to the Pennant Sandstone group, mid Carboniferous age that lie stratigraphically above the coal measures. The hard Pennant Sandstone forms the hills between the coalfield valleys. The roof of the tunnel is brick lined. In parts this looks quite clean, but in others, mineralisation has covered the brickwork. The tunnel is slightly s-curved, therefore it is not possible to see either end from within the central mile of the tunnel. At the centre of the tunnel, there are two enlarged workman's recesses, containing a fireplace and bench, designed for worker's breaks. Near the west end of the tunnel, still bricked up, the bore is wide enough for twin track, and there is a ruined building where the tunnel narrows, perhaps an underground signalbox. The construction style varies along the tunnel. this is probably a function of the geology and different working paractices between contractors. It was noted that the construction of the tunnel rendered to GWR sub-contractors bankrupt. Tunnel construction was slowed by the inability to construct any access (air) shafts due to the depth beneath the hillside (about 200m (660ft) at deepest point) .The tunnel dips slightly to the east.

East portal	Engineering code	From east portal	Towards east portal
West from east portal	Looking west	Poorly joined brickwor	Drainage trough
Workers refuge	Workers refuge	Workers refuge	Workers refuge
Near the middle	Reinforcement rings	Drainage trough	Workman's rest area
Workman's rest area	Different profile	Light at the west end of the tunnel	Underground shelters
Double track section	East from west portal	Underground shelters	Underground shelters
Colourful brickwork	Wooden construction shuttering	Wooden construction shuttering	West Portal

Railways index