Complex sentence: The line, engineered by Isambard Kingdom Brunel, was built as broad-gauge but it had been reconstructed as a mixed gauge line to accommodate local-gauge traffic by 1 June 1875, and broad-gauge trains ceased operation on 20 May 1892.
Split into simpler sentences: The line, engineered by Isambard Kingdom Brunel, was built as broad-gauge. It had been reconstructed as a mixed-gauge line to accommodate local-gauge traffic by 1 June 1875, and broad-gauge trains ceased operation on 20 May 1892.