Insight into how CTA built Train Tracker by Text


CTA passengers wait for trains in the Loop. Photo by Jim Watkins. 

Last week I excitedly announced the launch of the Chicago Transit Authority’s new system to get predicted arrival times for trains by text messaging (also known as SMS). I thought that the messaging syntax and the station codes were amusing but clever.

I emailed Tony Coppoletta, the CTA’s manager of external electronic communications manager, to ask about how the codes came to be, as well as upcoming Train Tracker features and the capabilities of SMS communications. Coppoletta directs how they reach their customers and partners with information about CTA services through digital means. 

What was the logic in deciding to use the alphabet instead of numerals, like Bus Tracker?

Train stations, like bus stops, have unique numerical IDs that we could have used just as well. But with a fairly limited number of ‘L’ stations, as compared to our nearly 12,000 bus stops, we saw an opportunity to make this new service even easier to use by assigning codes that people could more easily remember. Each is intended to be similar enough to the station name to act as a sort of “mnemonic learning device” to make them easier to remember.

Were there any codes that were troublesome to? Did any stations require some deliberation?

Absolutely. When designing a service that you expect people to interact with daily, you need to think a lot about the user experience. Like with airport codes, the most obvious combinations are not always feasible, for any number of reasons. So we’d start with a station name, then consider routes served, then maybe a cross street, all to use familiar strings of text and cues. If one of several equally good options are actual English words or otherwise pronounceable, all the better. Thus LOGA would have been fine for Logan Square, but LOGS is going to be really easy to remember.

Dealing with similar or same station names adds further cause for deliberation. For example, there are two stops named “Belmont,” miles apart. To distinguish, you could try and include a reference to routes that serve a station (thus BELB for the Belmont on the Blue Line), but there are three routes that serve the Belmont on the North Side Mainline. Rather than favoring one, considering that stop’s extraordinary usage, BELM seemed a fair compromise to just go with the first four letters of such a major station’s name. Remember, the focus is really uniqueness and memorability, so they’re not always obvious for the purpose of guessing at them, but they should be easy to recall once you’ve used them once or twice. (That said, we’re adding in some features to help foolproof the system by anticipating that some will try to guess and, even if they guess incorrectly, we’ll try to handle that gracefully).

I see that the Sox-35th Red Line station is SOX, but the Addison Red Line station is ADRE. Why not call this one CUBS?

“Sox” is the first word of the station name in the case of Sox-35th. The station closest to Wrigley Field doesn’t have “Cubs” in the name. We could have gone any number of ways, but SOX seemed the logical conclusion for Sox-35th. 35RE is similar to a stop a couple blocks away and didn’t want to confuse people who might switch between them, and SOX3 seemed like an unnecessary character addition for these purposes, so we settled on SOX. So sometimes we just needed to make a judgement call, and in this case we sided with simplicity. Since these are intended to be learned (as opposed to being guessable), we hope people appreciate not needing to type extra text in that case and find the approach to be much easier than numbers. And again, we’re working on adding some flexibility to help anticipate guesses and handle them without a hitch, as an added bit of polish on the service.


Photo of the Berwyn (BERW) Red Line station by Andy Marfia. 

What is your favorite code?

FORP. It’s fun to say. ROCK is pretty good, too.

What can CTA riders expect next with Train Tracker?

We just rolled out “favorites” and “recent” stops to make it easier to jump to relevant info on either the desktop or mobile site. We’ve also added integrating text instructions with Train Tracker results pages, so the info is easier to find during this early stage of testing for the text messaging feature. Later, we’ll likely include it in posted timetables online and at stations – but probably not until it’s already necessary for us to design, print and post them as a part of our regular schedule updating.

Down the pipe are some other improvements I don’t want to get into too much detail on, but a “follow this train” feature will be one, so you can, as your train approaches, pick a train and then see its expected progress en route. But there are a few other nice things coming down the pipe before we consider this as having graduated beyond “beta.”

How will “station favorites” work on the website? Will people have to create an account to save favorites?

It stores a simple cookie, locally, so no registration or login will be required. The goal is to keep it simple and just have it work well with little or no special effort on the part of the user.

Can the CTA offer new features by SMS, or has the limit be reached? Like, what else is possible in 160 characters?

There is only so much we can squeeze into a text, but we’re certainly open to offering more through this popular medium. While what you see is what we have at present, we’ve always got an ear to the ground to see what areas we can focus on to better inform and empower our customers. If you haven’t, I encourage you to visit to sign up to have text alerts pushed to you on routes and at times where it’s relevant. And also, as smartphones also proliferate and come down in price, the apps people are making with data we’ve published do some pretty incredible things. Texting is just one tool in our toolkit [see all the tools] to get word out that can help people have a better commute. [end]


I created this video to show how fast and easy you can get predicted train arrival times via text messaging. Get the station codes. This is geared towards users without smartphones, but those with smartphones may find it faster to use than dedicated apps.

I appreciate that the CTA is concerned about usability and is taking steps to build a robust system that can help users deal with forgotten or misspelled station codes.

Read previous reporting on train tracker and bus tracker, including information about Pace buses (who was first with a bus tracker) and Metra trains (who is mandated to track trains by 2015). 

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