sentences:  Bouch had laid out an economical route that followed the contours and avoided tunnels, but there were formidable gradients up to the high Stainmore Summit.Valleys were crossed by viaducts, including three made from wrought-iron that crossed the Tees, Deepdale and Belah rivers and cost a total of £77,400.The viaducts at Tees Valley, Deepdale, Belah and Smardale Gill were built wide enough for two tracks.