Caught on Camera: Modern Signaling Inside Tours

Just discovered this recent video from a Union Pacific signal maintainer giving a tour of a modern interlocking hut and other signal relay cabinets.  While getting the occasional photo inside one of these is not all that uncommon, narrated videos from North America are almost unheard of.  Anyway I'm not going to summarize the whole video, but some important takeaways are as follows. 

• Compare how little has changed between a 2019 setup and this 1992 setup I profiled from GREENBELT interlocking.  The US&S Microlock II card based, microprocessor controlled vital interlocking hardware especially.
  
  
• Track circuits, switch motor controllers and possibly signal lamps are still still relay controlled and not even the solid state upgrade variety.
  
  
• The local control board has reached peak levels of simplification/cheapness.
  
  
• Make sure you watch the whole video for a tour of a 1980's or 90's Southern Pacific all-relay interlocking hut at the end for comparison.
  
  
• The wiring job is quite professional.  I'm not sure if the installers have put more points into wiring over time or have benefited from computer aided routing.
  

In this video he discusses power operated point machines (specifically a US&S M23), however also heads into the relay hut to locally throw the unit.  Here we see an example of the protracted throw times that used to be common for low voltage DC operated points.  Due to the gear ratio, the motor takes around 20-30 seconds to throw the switch points as opposed to 1-2 seconds seen on 120v examples.

We also have a complete guide to electric hand throw switch locks and their operation.

In addition he posted a video tour of a grade crossing relay cabin, which, although not my wheelhouse, interacts with the signal system in some interesting ways. The first crossing profiled uses a speed predictor that uses audio frequency overlay circuits to directly measure the speed of the train instead of a fancy wireless negotiation. Others still have quite a few electro-mechanical relays present in various roles.