Tondu, formerly Tondu Middle, Signal Box is a Great Western Railway type 3 design and dates from 1884. It stands to the north of Tondu Junction Station (nprn 34882) and controlled a busy junction with the routes to Porthcawl and Margam to the west, lines in the valleys of the Llynfi, Garw and Ogmore from the north and the Bryncethin branch to the east. It is a two storey structure of brick construction under a pitched slated roof, with an external wooden access stairway at the north end. The GWR 5-bar Vertical Tappet frame was installed in 1963 and has 65 levers. By the 1970s, the box was modernised with 5-light windows inserted and brickwork refaced.
Only the north-south route in the Llynfi Valley and the lower Ogmore valley, carrying passengers between Maesteg and Bridgend, was noted in use at the time of a visit on 11 February 2010.

Sources include: Peter Kay, Signalling Atlas and Signal Box Directory (Third Edition), Signalling Record Society, Wallasey, 2010, p.28; Network Rail, Signal Box Register (undated). For further information on the types and designs of signal boxes see: The Signalling Study Group, The Signal Box - A Pictorial History and Guide to Designs, OPC, 1986.

B.A.Malaws, RCAHMW, 09 December 2016.