Caption: A splendid slide taken by Bruce Mercer way back January 8, 1973. The image shows TH&B 73 leading the East Local, "Port Maitland job" over the diamond at E&O tower and the the NYC / PC CASO SUB. The east local by time table direction is actually a southward movement on the TH&B Dunnville sub was south and north direction whereas all the other TH&B subs were east and west. The interlocked crossing at E&O was mile 9.46 on the TH&B Dunnville sub and less than half a mile from the location the TH&B went over the CN Cayuga sub, mile 9.80, both of these "railway crossing at grade" were interlocked and controlled by a tower man, sometimes referred to as a lever man or signalman. All the signals governing TH&B movement through the interlocking were of the semaphore type. TH&B Dunnville sub had another crossing at mile 14.28 of the CN Dunnville sub. The Dunnville sub crossing the Dunnville sub. It was an automatic interlocking.