• Locating Trains with Defect Detector Calls

  • Discussion about the Union Pacific operations past and present. Official site can be found here: UPRR.COM.
Discussion about the Union Pacific operations past and present. Official site can be found here: UPRR.COM.

Moderator: GOLDEN-ARM

  by j3rsdm5
I am a new railfan in UP territory. I need some help with finding trains. I use railroad radio.net to help me listen to radio calls, and the FRA map to locate mileposts. Unfortunately, it's only ABS where I can go, so I rely on defect detectors. There are 2 defect detectors, both in different places, but both on a milepost 929.5, miles and miles apart. I can only drive to one. The defect detector makes calls in this format:

"UP Detector: Milepost xxx.x, Track X, total axles xxx, speed xx M P H, Temperature xx, detector out."

The thing is, I know that when you're facing north track 1 and 2 are side by side left to right. (generally) What's confusing is that the only thing that changes is the track number. Dispatchers must have some way to know which milepost 929.5 the detector making calls is on. Otherwise it would defeat the point. Can I use track number somehow? Any help is greatly appreciated.

Thank you!
  by Backshophoss
Is this in the Phoenix AZ area?, there's a Detector at MP 927.5 near Higley,east of Gilbert Az, on the Phoenix sub,
or a detector on the Gila Sub near Eloy/Toltec Az area.
  by mmi16
The Defect Detector radio transmissions go to the Train & Engine crews of the trains and is transmitted on the Road radio channel. The train crews know which track they are operating on, so they have no problems knowing that the defect detector transmission is for them. The Train Dispatcher, does not normally monitor the Road radio channel, and even if he does he has no obligation to communicate with the crews about it. If the Defect Detector reports a defect to the crew, the crew will 'tone up' the Train Dispatcher and report they are being stopped by the detector to inspect their trains.
  by Pj
As for the UP, the answer is "it depends".

Typically in multiple main territories, they try to locate them at the same milepost, and the detector (if it talks, not all do - but will on a defect) will announce which track it is on. This way if two trains are passing the same location, they will know which one it affects.

Now, where I work, they have replaced ABS with CTC and moved signal locations to standardize locations (previously due to realignments and other stuff the signals where "staggered" so to speak). Some of our detectors were also staggered between main 1 and main 2 due to this - and those did not state which track since main 1 might have been at MP 500.2 and the one on main 2 was at MP 500.8. The milepost alone tells us which track.

In most signalled territory (at least on original UP signaled lines, and I am sure others) the detectors are wired with the signal system and will cause the closest control point within reasonable stopping distance to display "stop" until the detector clears the train.