In 1963, about 500 metres before the concourse, an imposing six-storey concrete cube arose in the station yard. It was designed by SBB architect Max Vogt [de], and it has been the home of the Zentralstellwerk Zürich (central signalling control) since 1966. The then state-of-the-art relay-controlled interlocking system replaced the decentralised mechanical and electro-mechanical signal boxes in the station throat, including the Stellwerk «Seufzerbrücke» ("Bridge of Sighs" signal box), which had spanned the entire station throat just east of the Langstrasse.