sentences:  Brindley's tunnel was abandoned in the twentieth century after it was affected by mining subsidence.The length of Telford's tunnel is , and an electric tug was used between 1914 and 1954 to speed up traffic through it.Just beyond the northern portal, the Macclesfield Canal turns off to the south and runs parallel to the main line, which drops through two locks, before the Macclesfield crosses over on an aqueduct and heads north.