Danger. GX1, Leitz Summicron 50mm DR

This fancy new signal gantry was erected a few months back on the Fitchburg commuter rail line right next to the clinical site where I work.  That red signal controls the eastbound track going into Boston's North Station.  Just a second after I took this photograph, the signal light changed to orange, indicating that the eastbound train in that block section had just departed the eastern end.  It would presumably change to green to indicate that it is completely safe for another eastbound train to enter that section.The left-most signal is for the westbound trains entering West Concord station, and the two in the middle are to serve a couple of spurs ("sidings" in Brit-speak) which are still to be constructed.  In the meantime, those two face sideways to the tracks.  
In South Africa, where railways were built single-track to save money, it was absolutely imperative to control what train was in what section and when.  This was achieved by a system of tokens, in addition to the information given by semaphore signals to the engineer.  He had to have the token held in his sweaty paw giving him permission to proceed into the next section.  No fancy color light signals.  When the train left the section the engineer relinquished the token to the station master of the next section up the line.  It was very exciting for young'uns such as myself to be standing on the platform of a country station and hear the telegraph bell ringing to announce that a train was coming.  The telegraph machine was connected to another device which dispensed the token.  This was placed in a little holder attached to a big bamboo ring.  The station master would then stand in a little raised "pulpit" right next to the tracks, and as the locomotive roared through the station, the engineer's assistant or the fireman would extend one arm out of the locomotive cab and hook the bamboo hoop with his elbow.  The other sound I associate with this ritual is the clanging of the signal levers in the cabin as the station master set the signals to "clear".  Lever and signal were connected by hardened steel wires and the wires had a particular "singing" sound as they rubbed against each other. It was all so thrilling! In retrospect I would even say "romantic".  Now there's just that sanitary color light signal and Central Traffic Control and very fond memories from another time and place.