Tag Archives: signals

Repeater signals

Another post about signals… this time the rail kind. I thought about this while writing the last post, because this is sort of like a literal signal boost.

There are two signals on the Banfield between Lloyd Center and Hollywood TC that function differently from the rest of the signals on the alignment. These signals (34R and 36R) are repeater signals. They “repeat”, or display the same aspects, as ABS signals 34 (eastbound) and 36 (westbound) respectively, but are positioned slightly ahead of the signals they repeat because those signals are around a curve.

34 R (eastbound), which is repeating the aspect displayed on…

…Signal 34

Signal 36R does the same thing for signal 36, which is seen going westbound. I don’t have a picture of signal 36, but here’s its repeater signal:

Signal 36R (westbound). Signal 36 is located around the curve ahead, back-to-back with signal 34.

The speed limit through here is 45 mph, so due to the limited visibility with signals 34 and 36 being on a curve, it would be difficult to stop a train in time if those signals were red. The repeaters give advanced notice of what aspect those two signals are displaying so operators can act accordingly and stop if necessary.

Notice how there are no ATS magnets near the repeater signals, but you can see the ATS magnet (it looks like a small box between the rails) in the picture for signal 34. Going through a red on 34R or 36R won’t automatically bring your train to a stop, however, you still treat like all other red signals and stop your train prior to the repeater if it’s red. And if you run a red on a repeater signal and then trip the signal after it, I believe that counts as two rule violations for going through two red signals (which I’ve never done..).

Train numbers, route codes, and more with signals

Question: How does a train know where to go?

This question comes up a lot, and although I’ve answered it in comments or emails or Twitter, I’ve never given it its own post. But a lot of people have asked, for example, if a train is eastbound at Gateway, what do you do to it to send it to Gresham vs the airport vs Clackamas? Sure you call the signal but how do you get the right aspect(s) to come up for where you want to go? It’s not like the trains have a steering wheel.

(Actually it’s kind of fun to let kids see the cab of a train at the end of the line and ask them where the steering wheel is. It stumps their parents too!)

It’s a trick question.  Here’s the “steering wheel” of a MAX train:

Route code (and train number, which is blurred out, you don’t need to know what train number this was, but in following safety procedures, I assure you the train was stopped at the end of the line – not only was it not moving it wasn’t even keyed in), Type 2 thumbwheels

In the cab of each train is a place to set the train number (under normal operating conditions, this won’t change over the course of the day) and also the route code. The train number is the train’s identifier, and it matches the number visible in the window box – for example, the train in the old header picture of this blog was train 40; the train in the old background image was 71. If Control wants you, they’ll call your train number over the radio. If you need something, you begin a radio call to Control by stating your train number.

You can tell what yard a train is from (though not necessarily what yard the operator is from due to reliefs) and what color its route is from the train number. Trains 1-15 are Blue originating out of Ruby, 20-38 are Blue out of Elmonica, 40-53 are Red out of Elmonica, 60-74 are Yellow/Green out of Ruby, and the Mall Shuttle had been train 89 out of Ruby. Trains not regularly scheduled, such as those used for testing or burn-in get numbers in the 90s. There are some exceptions to this breakdown, like train 10 is Blue most of the day but becomes Red at night, 43 begins its day going from Elmo to PDX to Hatfield before becoming a regular Red Line, but this is all pretty much just trivia for passengers anyway, it’s not like I’m going to quiz you on this later.

The route code is what tells the train where to go from its current location. Every possible destination on the alignment that can be reached via power switches has a route code assigned to it – not just the ends of each line, but also the yards, sidings, pocket tracks, etc.

Sign at Galleria with 11th Ave route code

In the first picture in this post, a route code of 50 will get a train to either track 1 or 3 in the Jackson turnaround by PSU, whichever is open. Every time an operator places a train-to-wayside call over a call loop, the switches will be set to move the train toward the destination set as the route code, and the corresponding signals will be displayed. Operators are responsible for ensuring the route code is correct for where the train is supposed to go. For Blue and Red line trains, this is pretty easy – the cab that leads going east will be set for Gresham or PDX, and the cab that leads west will be set for Hillsboro or BTC so it does not need to be adjusted frequently (well, it’s easy as long as Red line operators don’t forget to change the route code from the BTC pocket track on the last trip and end up in there when they need to keep going west…).

Yellow/Green line trains are a little trickier. For trains leaving Ruby to service those lines, depending on which run it is the route code will be set for Expo, the Jackson turnaround, or the Gateway auxiliary track (where the operator will swap cabs and take the train to Clackamas). Then to change color at Jackson, the operator will leave Clackamas (for example) with the route code for the Jackson turnaround, and then once there will set the route code for Expo. When leaving Expo in the other cab, they’ll set the route code for Jackson, and then once in the Jackson turnaround, they’ll change the route code for Clackamas. Potential errors can happen if an operator forgets to change the route code from 50 when leaving Jackson (if that happens, the train will head back south to PSU from Union Station instead of crossing the Steel Bridge) or forgetting to set the route code for Jackson from the end of the line (so for example, heading toward Clackamas from Interstate Rose Quarter instead of over the Steel Bridge).

Signal aspect review

Signals will reflect what route code is in your thumbwheel. First, here’s a quick overview  of signal aspects (for more information, I’ve written a lot about signals already)

A red aspect – STOP

A yellow aspect – clear for one ABS block (that is, the distance to the next ABS signal) on the primary route

A green aspect – clear for two ABS blocks on the primary route

A lunar aspect – proceed with caution, tracks may not be clear (your switches are set but no indication of train occupancy ahead)

The number of aspects that are lit indicates which route you’ll be going on (one aspect = primary route, or “A” route. Two aspects = secondary route or “B” route. Three aspects = tertiary “C” route, etc). As an operator, when you’re looking at a signal that can display more than one route, you need to know which of those routes corresponds with the route code you have in your thumbwheel.

Back when I was first learning the signals, one of the most confusing parts for me was confounding signal aspects with switch positions, in part because yellow over green signals are referred to as “advanced diverging” and red over yellow are referred to as “diverging” – so that means when you see one of those signals, you can expect switches to be set diverging, right? Well, not necessarily…

For example, at the ends of the lines (here into Cleveland Ave from Gresham TC) a single yellow aspect will actually put you over diverging switches into Cleveland, but a red over yellow is a straight shot in. A signal with two aspects means that you’re diverging from the primary route, but not necessarily diverging over switches – it could be that the primary route itself diverges over switches but the secondary route goes straight. I had been thinking about the ABS signals in terms of switches, not routes, and that was a stumbling block for me. A permissive signal indicates that your switches are set for whatever your route code is, but you have to know if that means they’re diverging or normal.

Same with this red over white vertical on W1760 at Hatfield – it’s a secondary route (2 aspects), but this train will be going straight in, not diverging over the switches. Sorry for the blurry picture but it’s the only one I have.. I either need to go out there and get a clearer one or get someone to do that for me.

It’s not where you are, it’s where you’re going

So keeping in mind that an ABS (or ABS-pre-empt combination) signal displays your route, here’s an example of what it looks like when you can call the same route from two different locations. Take a look at these signals:

Signal 76: Red over red over green
Clear for 2 ABS blocks to Clackamas TC

Signal 78: Red over red over yellow
Clear for 1 ABS block to Clackamas TC

Both trains that called these are facing east at Gateway – the one looking at signal 76 is in the eastbound main; the one looking at signal 78 is in the pocket track. Both have a route code set for Clackamas TC. And from both tracks, that’s the “C” route / 3rd route / tertiary route, which is why both signals are showing 3 aspects. These aspects are almost functionally identical (the yellow on 78 just means that this train’s leader is only one ABS block ahead of them, otherwise that would’ve been a green) even though the train observing signal 78 has two more sets of switches to diverge over to get to the eastbound main to get to Clackamas.

Gateway from above, click for larger

The platforms are in the bottom of the picture – from left to right, that’s the westbound mainline, pocket track, and eastbound mainline. Notice that to get over to the eastbound main alignment (which, out of range of the top of the picture, diverges off to Clackamas) a train in the pocket track has to pass over the switches that could otherwise bring it to the auxiliary track, and then over another set of switches to join the eastbound main. Yet its signal aspect at Gateway to get to Clackamas is identical to what a train in the eastbound mainline would get, even though the train in the eastbound mainline doesn’t have to worry about those switches.

Where a train is starting from doesn’t matter – where it’s heading is what will be displayed on the signal.

Lunar on signal 78, eastbound from Gateway pocket track

Lunar on signal 76, eastbound main at Gateway

Similarly, a train with a route code for Cleveland (or the Ruby Yard) going east from the pocket track will get a single lunar aspect on signal 78, just like how a Blue Line train heading east at Gateway will have a lunar on signal 76, even though a train starting from the pocket track has to diverge over switches to get there. The signal indicates that the switches are set for the route code in  your thumbwheel, but you have to know if that means the switches are set normal or diverging (because you do NOT take a train at a high speed over these diverging switches!)

Here’s another example, eastbound at Beaverton Transit Center.

Signal W760 is for a train in the pocket track (which is typically a Red Line), and W754 is the signal for the eastbound main. A train heading east from the pocket track will have to diverge over switches to get into the eastbound main, yet the ABS signal will show a single aspect indicating the primary “A” route. It doesn’t matter where the train is at, it matters where it’s going – and for trains in either track here, the only place to go is the eastbound main (primary route), therefore both signals have a single head that can only display a single aspect. There is no choice of route from either track, even though you will be diverging into the main eastbound track if you are leaving the pocket track.

W556 at Sunset, for a Red Line train heading to the BTC pocket track

On the other hand, if you’re headed west into BTC, you do have a choice of two routes (along the westbound mainline or into the pocket track), which is why signal W556 at Sunset and the intermediate signals leading into BTC (W616 and W716) can all display one or two aspects for a primary or secondary route. The signals will indicate that the switches are set for whichever of those route codes you have in your thumbwheel.

You know, I don’t know how to end posts. I feel like I should assign a 2-page essay on the importance of ensuring you have the right route code in your thumbwheel and how that relates to ABS signal aspects. Show your work.

Manual blocks and reverse traffic

I recently was asked some questions about

Manual blocks

(and this post got long… you might want to go make a nice sandwich or something for yourself before settling in to this one)

When train movement on one track is not available, a manual block is used to move trains on the adjacent track. This could happen because of planned maintenance, or it could be done in the event of an accident/emergency situation. In a manual block, Control directs train movement in both directions on the track that is in service. Manual blocks will have associated train orders.

You’ve done the equivalent of a manual block in your car before if you’ve gone through road construction where only one lane is open. For cars in that setting, there’s a flagger at each end of the construction area that lets a number of cars through and holds oncoming traffic from entering the single lane, and then they switch to let cars from the other direction go through. A manual block for trains is essentially the same idea – Controllers and supervisors coordinate to govern train movement into a manual block, alternating between trains running normal traffic (e.g. east in the eastbound) and others running reverse traffic (west in the eastbound).

Reverse traffic

Borrowed photo. This is not a manual block, but it shows a train running reverse (here east in the westbound at Willow Creek)

Running reverse traffic is not the same thing as backing a train up. An operator backing a train up (such as in the case of uncoupling a train car) can’t see in the direction that the train is moving – this is why backing a train up is almost never done. When an operator is running reverse traffic, they face in the same direction as the train’s movement, but that movement is in the opposite direction of what the track they’re on is typically used for.

There are a number of rules that govern running reverse traffic. First, it’s always done at restricted speed (the lesser of 20mph or the posted speed and always at a speed that the operator can stop in half their sight distance) whether or not it’s part of a manual block, unless you’re in the tunnel. Because the tunnel is signalized in both directions, trains running reverse can operate at the posted speed limits which are about the same as normal speed limits, though trains going west in the eastbound bore will exit the tunnel much slower than normal traffic because they will be diverging into the west portal pocket track. Other areas of the alignment that are signalized in both directions are already single track, e.g. the “fishhook” for the Red Line at Gateway, so travel in both directions is normal.

While running reverse, operators will also have to stop and observe every set of switch points to ensure they are properly aligned. In ABS territory, running reverse traffic is where dwarf signals come into play – they protect mainline power switches while running reverse traffic. In other words, the ATS magnets associated with the dwarf signals are active for trains going the “wrong way”. Operators will have to key-by these signals (this is done from the operating console in the train cab) after calling Control. This gives the operator 23 seconds to move the train past the ATS magnet without tripping.

On Burnside, operators running reverse traffic will have to SOP the intersections since the mass detectors are only for normal traffic. If the reverse running on Burnside is part of a manual block, the train orders associated with the manual block will include instructions to SOP intersections within the block. So operators will not need to call Control for permission at those intersections, but otherwise the process to SOP them is the same – stop, wait for fresh parallel green and walk signal and red left turn signal, sound horn warning, and proceed when safe.

You may have seen these stop signs at gated intersections or in places where the view is obstructed by a substation building – these are for trains running reverse traffic since people are not likely to expect a train from that direction on that track.

Gated intersections are also handled differently when running reverse traffic. When running normal traffic, the gates are lowered either by a call loop if the platform is right near the intersection (such as the above picture of Elmonica/170th) or when the train enters the approach circuit as it approaches the crossing gate for gates that are not near a platform. There is another circuit that extends 10 feet on either side of and through a gated crossing called the island circuit. When the island circuit is shunted, it will lower the crossing gates if they weren’t already lowered – you won’t notice this running normal traffic since under normal operations the gates will be lowered by the time the train gets there, but when a train is running reverse traffic, it uses island circuits to lower the crossing gates. The operator will wait until the gates have been fully lowered for 10 seconds before proceeding through the intersection.

Manual Block

In a manual block, most of the rules that apply to trains running reverse traffic will also apply to those running normal traffic. For one thing, travel in both directions of a manual block will be done at restricted speed, unless otherwise instructed by Control.

Borrowed picture – Both of these trains are running normal traffic, but it shows switch points as the operator sees them. Here it is a trailing move since the points are facing away from our oncoming train

If there are switches in the manual block, operators in both directions will be required to stop and observe every set of switch points before proceeding, regardless of whether the switch points are facing toward the train or away from the train (as seen in the above picture).

A planned manual block will have a written train order, but operators about to enter a manual block, whether planned or unplanned, will still call Control before they enter to receive specific instructions. The instructions will have to be repeated back word for word, which ensures that there is no misunderstanding of the instructions, since manual blocks have the potential to be extremely dangerous. Even at 20mph, a train splitting a switch (making a trailing move over a power or t-rail switch that isn’t set for you) or hitting another train can cause serious damage. The specific details of the instructions may vary depending on where the manual block is and why a manual block is in effect – for example, a planned manual block may have pullback operators to pull the train through crossover switches so that the operator of the train doesn’t have to change cabs.

Previously, a “medallion” system had been used for manual blocks. A medallion was an object such as a stuffed animal (like the rabbit) that would be passed off to a train as it was about to enter the block. If you didn’t have the medallion in your possession, you would not enter the block. Nowadays that system isn’t used. Instead, a clearance sheet is used to record all train movement in manual blocks. This written record details the movement of all trains into, through, and out of the block, ensuring that only one train is in the block at a time.

Once an operator is clear of the block, he or she will call Control. Their train will be recorded on the clearance sheet, and the operator will then be able to resume normal operation. The next train will then be cleared to enter the manual block. This process continues for the duration that the block is needed. At that point, Controllers and supervisors will ensure that all trains are clear of the manual block and that all switches are aligned normal and locked. The first train through the track that had been out of service may be asked to sweep that section of the alignment, especially if the manual block was due to an emergency, and then following trains can operate as normal.

SOPing an intersection

In my last post about the mall, I mentioned how the intersections on the mall have secondary call loops, that is, call loops that are not located at a platform. Normally, operators don’t need to use these because the signals will be cascading from when the pre-empt at the platform was called. Secondary call loops are there to be used if the signal times out before the train gets to that intersection – they allow operators to quickly recall the signal to keep moving. That’s not the only way to get a pre-empt again - as I’ve mentioned before, some intersections are equipped with a push button, where an operator can reach out of the cab window and use the push button to recall the pre-empt.

However, not all pre-empted intersections have push buttons or secondary call loops. For example, on most of Burnside (which uses mass detectors instead of call loops) a train cannot get a permissive signal again if the pre-empt times out or fails to display a white vertical. Continuing through the intersection on a yellow horizontal is the equivalent of running a red light for a train – it’s a rule violation and it’s dangerous.

Stop

So if it should happen that a pre-empt times out or fails to change to a white vertical in the first place, and an operator has no secondary call loop or push button, there is a set standard operating procedure (SOP) to safely proceed through the intersection. If you’re listening to the radio and you hear an operator requesting permission to SOP the intersection, what they’re asking for is clearance to proceed on a yellow horizontal.

First, the operator has to stop the train before entering the intersection on a yellow horizontal. Next, they call Control for permission to SOP the intersection. If it is an intersection that can be safely SOPed*, Control will tell the operator to wait for a fresh parallel green and walk sign. Where applicable (e.g. on Burnside) the operator will also have to wait for a red left turn arrow.

*Not all intersections can be safely SOPed – here heading west into Goose Hollow, Collins Circle at 18th & Jefferson has a secondary call loop. However if an operator overshoots it, they will not be able to SOP the intersection

When the auto traffic lights have a parallel green and red left turn, the rail operator will  sound horn warning and proceed when safe. This includes checking for emergency vehicles. As seen from 2005, an emergency vehicle’s Opticom can’t make a white vertical go back to a yellow horizontal, but if they placed their call before you it will prevent a white vertical from coming up at that intersection.

Train vs Fire Truck, Hillsboro, 2005.

Open response to an open letter

I recently saw this complaint on Planet Feedback:

Tri-Met Train Engineer Refused to Open Train Doors

Posted Sat February 5, 2011 3:03 pm, by John T. written to Mr. Neil McFarlane, General Manager, Tri-Met

I am writing to inform you of an unpleasant experience on the Yellow Max Line to Expo Center. This is the text of my Tri-Met website email complaint, which I sent on 1/28/2011:
Engineer refused to open the door (Train 123, 1:28 p.m., Thursday,1/27/2011 at SW 6th Ave. & Morrison), even though there was ample time to do so. I crossed the street from Pioneer Square as the Expo Center train was stopped at a red light. When my light changed to green, I immediately crossed the street and quickly walked right in front of the stopped train, so the engineer had to see me. I hurriedly pressed the yellow and blue buttons for the doors to open on the first car. The traffic light was still red (for the train). They did not, so I attempted to open the doors with my fingers. Seeing the doors were tight and unyielding, I immediately removed my hands and stepped back. A second or two after I had stopped trying to open the doors, the engineer said over the external speaker, “You better take your hands off that door or you will be arrested.” Those words prove he had seen me while the train was still stopped. A few seconds later, some stranger walked up to me and said he had pushed the door open buttons too in the second car, and the doors did not open. The train was still stopped as he initially spoke to me. Both myself and the stranger were casually well-dressed and very sober. Generally speaking I like Tri-Met, but this engineer was out of line and needs retraining and/or some other appropriate sanction. I wonder how many other riders he has treated so poorly.

Please investigate the matter and the Rider Complaint procedure thoroughly, which appears to be deficient and in need of revision because of the following: The Tri-Met website did not generate a case number or any email to me with a copy of my issue after I sent it on 1/28/2011. Also, since I did not receive a timely confirmation via email or telephone after 1/28/2011, I sent an email on or about 2/3/2011. On 2/4/2011 I received an email (copy enclosed) stating that my issue was reported on 1/28/2011 to the Yellow Line Manager, and that it is a “private matter” between the manager and the employee. I am not satisfied with this closed system, as there is no real accountability to the public or myself. The public is supposed to trust what occurs behind closed doors, but we are not even informed of the outcome. This does not seem fair.

I was pleased to see the comments to the letter, where several people explained that once a train has its signal, it can’t wait for more people to board. Another commenter said it’s not appropriate to release disciplinary information to the public, which I also agree with. However, as for the original complaint, I know that John T is not unique in being mad that trains don’t wait for him and even though I’ve already written about the yellow door release buttons before, now’s as good a time as any to do it again, as well as explain a little bit about how the mall signals work.

First, a basic refresher on pre-empt signals – these display a yellow horizontal which means “STOP” to a train or a white vertical which means “PROCEED WITH CAUTION”. Because of how the CBD is set up, there are a number of intersections where auto traffic will have a red light (STOP) but a train will have a white vertical – this will be the case in any intersection where a green light could potentially turn a car into the path of a train.

SW 6th & Yamhill – red light for cars, white vertical for an eastbound train, and walk sign for pedestrians

So don’t look at the auto traffic signals to determine if a train is about to move or not, because at most intersections the train isn’t following those signals. The train having a “red light” in this case is irrelevant.

Now moving on to the rest of the complaint, which is essentially “the train didn’t wait for me and reopen the doors.” Well, no – the mall is not a good place for that sort of thing. Sometimes an operator of a north or southbound train will release the doors – that is, turn on the external door buttons so that passengers can push them to open the doors and let themselves on – if they are waiting for an eastbound or westbound train to pass or for the way ahead to be clear, but once they’re ready to call the signal, the doors are closed and it’s time to go. Here’s why:

Pioneer Courthouse, SW 5th & Yamhill facing south

This is a view looking south on 5th Avenue. On the top of the pole in the middle of the picture, you can see the pre-empt signal for southbound Yellow and Green trains to PSU. It’s displaying a yellow horizontal in the picture which is the default aspect until a train calls it. Now look down 5th at each intersection – you can see the auto traffic lights that are red and green on the left side of 5th, and on the right side you can see the pre-empt signals for the trains (all yellow horizontals).

SW 5th & Yamhill, wider view.
The pre-empt signals may be easier to see in this picture

If you ride a train on 5th or 6th, you’ll notice that ideally the train will only stop at platforms, not at the intersections between platforms. This is because those pre-empts cascade – an operator will call the signal at the platform, and then the pre-empts up through the next platform are automatically timed so that when the train gets to each intersection, the pre-empt will be displaying a permissive white vertical to proceed without the operator needing to do anything. In the event that the train has to stop (e.g. a personal auto blocking the right of way, a pedestrian running in front of a train, a car or cyclist running a red light – you know, those things that never happen) each intersection also has a secondary call loop where an operator is able to recall the signal. Under normal operating conditions, the cascading signals between platforms allows for the smoothest and fastest train movement.

South end of the mall by PSU looking north up 6th Ave. Notice the pre-empt signals on the right, the curve in the rails for the train to move to the center lane, and the bus ahead pulling away from its stop

But remember that the mall isn’t just for trains. The alignment runs serpentine with buses so that the trains and buses leapfrog up and down the mall with the rails cutting over to the right every few blocks for a platform, and then back over to the center lane for the blocks that are served by buses. The auto signals on the mall are in sync with the train pre-empts, so buses will be held on a red light to let the train move through and get out of the way when the train has a permissive signal since both buses and trains share the center travel lane and cross paths to service alternating blocks.

View from above of a Yellow Line train on 5th moving into the center travel lane after servicing the Pioneer Courthouse platform in the previous block

SO – getting back to why a train can’t wait “just a few more seconds” for you and reopen the doors… when an operator calls a signal at a platform on the mall, it starts the cascade of pre-empts up to the next platform. This cascade goes through even if the train stays put where it is, which can happen if the operator reopens the doors to let late runners on and then the signal in front of them times out. This delays buses unnecessarily as they are held at red lights waiting for a train that isn’t there. As a result, not only will the train you wanted to get on be delayed, but so will a bunch of buses because you weren’t at the platform when the train’s doors were open. Preventing that from happening, quite frankly, isn’t something an operator needs to be disciplined for.

And finally, I feel the need to defend the operator of that train – I know whose run that is and they’re one of the last people I could think of that would threaten a passenger with an arrest. I’m hard pressed to believe that such a comment was even made by the operator, but I’m not surprised at the accusation. I have seen operators scapegoated for everything that goes wrong for passengers (classic example – a bus running exactly on time and someone on the bus calling their boss “Yeah, the stupid bus was late again so I’m going to be late for work.”  Hey! Not the bus operator’s fault you picked a later bus than you needed. Take responsibility for your own actions.)