On the air


The TriMet online radio scanner (not an officially provided TriMet service, but hey, it’s open air radio…) has been growing in popularity, possibly in part due to the fact that there are sometimes delays between incidents and service alerts explaining the situation from TriMet, and some riders have discovered that they can scan the radio to try to find out what might be going on. Or maybe it’s just that some people like that sort of “behind-the scenes” look at what makes everything go.

However, a lot of what you’ll hear over the radio might be confusing if you haven’t had any inside exposure to how the system works. So this post is intended to give an overview of what you’ll typically hear on a day-to-day basis if you scan rail radio. If you have your own scanner and want to program it to listen to TriMet, the frequencies and talkgroup IDs you’ll need are all listed here.

Communications between rail operators and controllers

On the mainline, operators are identified by their train number. So let’s say, for example, you’re the operator of train 3. If you need to contact Control for something, you will initiate your call to them by stating “Train 3.” The controller of the air you’re in will acknowledge your call by repeating your number back to you. (Alternatively, if the controller is the one initiating the call, they will contact you by stating “Train 3”.) At this point, you respond with your TDL – your Train number, Direction, and Location.

TDL confirms to Control where you are, and also basically gives a heads up to the trains around you if they need to pay close attention to what you’re going to say. For example, if I’m westbound at Lloyd Center and I hear you call in “Train 3, westbound, OCC”, I’m going to pay close attention to what you say because if the reason for your call is a mechanical/police/medical issue, that could potentially delay me since you’re only two platforms in front of me. But if I’m westbound at Lloyd and I hear you say “Train 3, eastbound, 60th”, I don’t have to be too concerned about it because you’re behind me and going in the other direction, so even if you are delayed it most likely won’t affect me.

In certain instances, you can add a word to your initial call to provide additional information to Control. The most common of these you’ll hear is “Relief,” which is used when another operator’s shift is ending and you’re taking over their train on the mainline (as opposed to taking one out of the yard yourself). In this case when Control calls back, you provide your badge number and location. So for example, if I’m relieving train 66 at Gateway westbound, I’d call in “Train 66 Relief”, they’d answer “Train 66”, and I’d reply “Train 66, operator 1234*, signal 72” and let them know if I was signed in and had my train orders. Then they’d let me know if there was anything going on that I should know about that could affect me (track work being done, Blazer game, etc).

*not anyone’s actual badge number as far as I know.


You might also hear someone call in with a “Defect” –  for example, if you notice that when you go into the tunnel, it’s darker than normal and realize it’s because your cyclops doesn’t seem to be working, you’d call in “Train 40 Defect”. After Control answers you, you reply with which car/cab you’re in and what the defect is so they can write that up.

You hope you don’t hear someone call in a “Priority” which informs Control that a train has made contact with a person or a vehicle. These are thankfully rare, but adding priority to your initial call lets everyone else know to keep non-emergency calls off that air because this could potentially be a life-or-death situation and you will need to be able to communicate to Control without being interrupted.

On occasion you’ll hear “Train 3, Train not moving” which is exactly what it sounds like. Alternatively, an operator might just call in with just their train number and after Control responds, inform them that they aren’t moving and what kinds of problem indications they’re having. This will usually lead into troubleshooting, which I’ll save for separate posts because the types of things that can go wrong and what’s done to fix them are too lengthy for this kind of basic overview.

Call Signs

You’ll hear other numbers that aren’t trains being used as identifiers on the air. If you’re just scanning rail, you’ll hear 4-digit numbers beginning with “Nine five”. These are the call signs for rail supervisors. If you’re scanning everything, the 4-digit call signs beginning with “Nine one” are road supervisors, “Nine four” are fare inspectors, and “Nine nine” are lead supervisors. Communication between supervisors and controllers is somewhat similar to how it is for operators – if a supervisor needs to contact Control, they state their number (e.g.”9501″). If a controller needs to contact a supervisor, they’ll state the supervisor’s number, and the supervisor responds by giving their number and location.

Probably the other most common call signs you’ll hear are 3-digit numbers beginning with 6. These are mainly going to be the folks working in the right of way, doing switch and signal maintenance, inspecting the overhead wires, cleaning litter or other debris, etc. Work that they do will generally have an associated train order, which you will hear.

Train Orders

trainorderController’s name removed, no personal information is given out here

If you scan rail radio for a while, you will almost certainly hear train orders mentioned. Remember that a train order is a temporary (24 hours or less) modification to normal operating rules. Control will inform operators over the air when train orders go into effect and when they’re cancelled.

I’ve mentioned call boards before for workers in the ROW, and now you can piece together how that plays out:

  • The call boards go up and the train order goes into effect.
  • Control verbally informs operators that the train order is in effect and what they will need to do (e.g. calls westbound from Sunset and eastbound from BTC).
  • Your train arrives westbound at Sunset. You call and give your location.
  • Control contacts the workers in the ROW (“Unit 666*, there’s a westbound at Sunset”), and 666 responds when it is clear for the you to call your signal.
  • Control gives you permission to proceed on a proper signal
  • This is a HUGE safety issue! I’d posted a short video about this in an earlier post

*there actually isn’t anyone who’s got the mark of the beast as their call sign.

And now, frequently heard quotes on the air:

“Clear on a proper”

Trains can be instructed to hold in place for a number of reasons – as mentioned, waiting for permission to proceed after calling at a call board, holding for emergency/medical/police activity (on your own train or one in front of you), holding because a train in front of you is having a mechanical problem, etc. When things are finally able to get rolling again, Control can’t just tell you to “go”…

120What’s going to happen if I try to go forward now? I mean, aside from the fact that I’m not even in the operating seat, or keyed in.

…so instead, they’ll give you permission to proceed when you have a permissive signal, aka that you’re “clear on a proper.”

“Permission to SOP an intersection..”

This one got its own post a while ago. There will be instances where a pre-empt signal times out before an operator is able to get through the intersection. When this happens, the operator will call in for permission to SOP the intersection, that is, follow the Standard Operating Procedure for how to safely go through the intersection when you don’t have a permissive signal to do so (short version – wait for fresh parallel green light, sound horn warning, proceed when safe).

“Substation is Offline, Notch in the area”

The substations that power the overhead wires will be periodically taken offline for maintenance (the techs that do this work also have call signs in the 600s). When a substation is offline, operators are instructed to “notch in the area.” As a passenger on the train, you’ll be able to tell if a substation is offline if you feel the train leaving very slowly from the platform.


Going back to this picture of the propulsion modes, what your operator is doing when they’re notching up is taking a very small point of power at first, and then spending a few seconds at each propulsion level before notching up into the next one. This prevents arcing or other electrical damage until the substation is back online.

End with time

Control will end transmissions by giving the time (24 hour clock, so it’s not 2:30pm, it’s 14:30).

One response to “On the air

  1. It’s best to listen using Real Player, Winamp or other players that will show metadata. That way, you’ll know what you’re listening too. There’s a lot of things in that feed–besides the 4 MAX channels, there’s bus dispatch, bus calls, LIFT and streetcar.

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