The Reading–Taunton line is a major branch of the Great Western Main Line from which it diverges at Reading railway station. It runs to Cogload Junction where it joins the Bristol to Exeter and Penzance line.

The Great Western Main Line (GWML) is a main line railway in England that runs westwards from London Paddington to Bristol Temple Meads. It connects to other main lines such as those from Reading to Penzance and Swindon to Swansea. The GWML is presently a part of the national rail system managed by Network Rail while the majority of passenger services upon it are provided by the current Great Western Railway franchise.