 Some of the signals in the tunnel section were disc signals and some semaphore signals at stations between the tunnels had foreshortened arms.In 1956 modern colour light signalling was installed on the line, controlled from Stobcross and Bridgeton, with track circuit control intermediately.This enabled the closure of boxes at Dalmarnock, Glasgow Green, Glasgow Cross, Glasgow Central, Anderston Cross and Partick Central No.2.