sentences:  From the first proposals of the Carmarthen and Cardigan railway it was known that an expensive and long tunnel would be needed to take the line between the valleys of Skanda Vale (in which Llanpumpsaint station resided) and Dolgran, under the Brechfa Forest watershed.Several separate Engineers surveyed the line, including Isambard Kingdom Brunel, with varying schemes.Brunel proposed a dead-straight tunnel to connect the valleys, though after reworking, the final design was longer in order to ease the gradients.