The state of transit trackers in Chicago


A CTA passenger waits for a train in the snow at Belmont Brown Line station. Photo by Mike Priorie. 

Knowing when your bus or train is about to come can help you make better decisions. “Do I have enough time to get coffee from the shop across the street?” “Can I pack my own lunch today?” “If I miss this bus because I can’t find my good shoes, how long will it be to the next one”? I’m sure we’ve all asked ourselves these questions*. The Chicago Transit Authority’s transit tracking services can help with the answers.

What is Transit Tracker?

Transit Tracker is a service provided by the Chicago Transit Authority (CTA) that provides information on when a bus or train will arrive at a specific stop or station. The information is given as a “countdown timer” based on the vehicle’s current position, the schedule, and historical arrival data (which may include recently recorded travel times). (Transit Tracker is not a name that CTA uses, but a generic term I’m using to represent both of their services, “Bus Tracker” and “Train Tracker”.)

Bus Tracker was launched on August 5, 2006, as a pilot program at a single bus stop for route 20/Madison; an electronic message board was installed in the bus shelter. Over a year later in March 2008, the CTA added bus tracker to thirteen routes that could be accessed via The last routes were added in May 2009.

Train Tracker was launched on January 8, 2011. I wrote about this launch and my involvement as a tester for CTA on Steven Can Plan.

How does Transit Tracker work

Bus Tracker uses Automatic Vehicle Location (AVL) technologies present on the bus. A PC on the bus connects to GPS satellites to determine its current location; when a GPS signal is not available the PC uses the “deduced reckoning” method to determine how far it has likely moved since its last known location. These methods are very accurate and allow for the Automated Voice Annunciation System (AVAS) to announce the next stop at precisely the right time. Bus Tracker is based on Clever Devices’s BusTime product.

Instead of GPS, Train Tracker uses block signaling technology on the tracks to determine the approximate location of the train (read more on A train can only be identified by the block it occupies, a length of track longer than a single train. The estimated arrival times are generated “by first measuring how long it takes a train to travel a portion of track and then averaging the times of the last five trains to move across a portion of track” (Train Tracker press release, January 8, 2011). Train Tracker was developed in house and uses QuicTrak software by QEI, Inc.

Both trackers provide passengers with estimated or predicted arrival times.

What has happened since Transit Tracker started?

After a Chicagoan reverse engineered the Bus Tracker feeds and wrote documentation for others to access the feeds, the CTA formally released an application programming interface (API, the feeds) and its own documentation. It then encouraged developers to use the API to build apps for the web, mobile devices, and other platforms (like dashboards in Mac and Windows). The CTA website features these apps.

For my Android HTC Sensation, I use Chicago Transit Tracker Lite although I just installed Transit Tracks tonight after a friend recommended it to me. Both allow you to add favorite bus stops and can locate nearby stops. I’ve posted a more detailed comparison.

APIs are available for buses, trains, and customer alerts. The CTA also provides for download the same data that Google Maps and other platforms use to generate maps and trips for using transit (called General Transit Feed Specification, or GTFS).

How often is Bus Tracker used

In 2009, the CTA changed thousands of bus stop signs with new signs that included instructions for customers to use the Bus Tracker program using a cellphone with text messaging capabilities. This program greatly expanded the potential user base for Bus Tracker to those without mobile web access, or web access at home.

I asked the CTA for information on its Bus Tracker by text message system for retrieving bus arrival times via text messaging (SMS). This feature was introduced on December 22, 2009. The CTA signed a two-year contract with TextMarks, an SMS marketing firm, to provide one million text messages per month. The CTA pays $3,500 per month for this service, or 3.5 cents per text message; it does get rollover messages.

I also asked the CTA for usage information. The results are fantastic: people are querying the system often! And it looks like so often enough that the CTA will have to upgrade its monthly plan (see table 1 below).

Why SMS access is important

The CTA should provide services universally to all passengers, agnostic to the technological capabilities of each passenger. Instead of creating its own iPhone or Android applications, the CTA rightfully abstained from this and instead created the ecosystem for private developers to do so. In addition to the ecosystem, the CTA has created a small market for those developers who have paid apps.

While it is easy for customers to access the official bus tracker website from home or work on a personal computer, not everyone has the equipment to access the helpful information on the go. Providing the service by SMS made the service more equitable. Some statistics follow:

  • “Some 83% of American adults own cell phones and three-quarters of them (73%) send and receive text messages” (Pew 1).
  • Only 44% of cell phone users access the internet (Pew 2)
  • As for smartphones, “One third of American adults (35%) own a smartphone of some kind” (Pew 2).
  • 80% of smartphone users access the internet (Pew 2).
  • There’s a significant population of Americans who reported mostly using their smartphone to go online, about 25%. One-third of this population lacks a home broadband connection. (Pew 3)

What are the benefits of Transit Tracker


W Grocer in Wicker Park provides a bus tracker display at the checkout counter, using the CTA’s DIY transit tracker. If it’s raining outside, you can wait inside for a few minutes until the bus comes. The Aldi in Wicker Park also has a DIY bus tracker

A Transit Tracker doesn’t only benefit a transit agency’s customers; the transit agency can receive its own benefits. I’ve listed their benefits in two categories: customer facing, and internal support.

Customer facing

Transit trackers have been shown to increase passengers’ perception of the quality of service the transit agency provides. The following excerpt comes from a report about the OneBusAway tracker in Seattle, Washington.

There are two principal reasons for providing better transit traveler information: 1) to increase satisfaction among current riders; and 2) to increase ridership, especially among new or infrequent transit users and for non-peak hour trips.

It has been shown that transit traveler information can result in a mode-shift to public transportation. This stems from the riders’ ability to feel more in control of their trip, including their time spent waiting and their perception of safety. Existing studies…have shown that the ability to determine when the next vehicle is coming brings travelers’ perception of wait time in line with the true time spent waiting. Transit users value knowing how long their wait is, or whether they have just missed the last bus. In addition, it has been found that providing real-time information significantly increases passenger feelings of safety.

Download the report from University of Washington (PDF). I’ve provided a longer summary of this report on Steven Can Plan.

The variety of applications built on the Transit Tracker platform also help to create better opportunities to provide focused tools for people with different cognitive and physical abilities. These tools may be provided by the transit agency, or by the developers using the APIs.

Grid Chicago is in support of programs and policies that increase the population’s use of transit. Transit Tracker provides passengers with accurate information about the movement of transit vehicles enabling them to make the appropriate choices about their trips. They improve service reliability which has the real effect of attracting new customers.

Internal support

The “enabling technologies”, the systems that power the location and announcement systems, are also used to monitor the transit vehicle’s operational status. The following advantages were identified in a report for the Federal Transit Administration (FTA) about the return on investment of real-time travel information (transit trackers).

  • Improved schedule/planning efficiency – “The monitoring capability of enabling technologies together with the analysis of the data allows the agency/operator to make better long-term decisions about service planning.” Page 42
  • Improved operating performance – “Services that show poor operating performance (e.g. poor schedule adherence due to recurring congestion) can be altered to improve productivity and reduce the fleet, labor, equipment and other material requirements for operations.” Page 42
  • Incident response – “The control center may be able to track the location of all vehicles with a certain level of confidence to determine the impact of an incident or non-recurring congestion on operations. Dispatchers can use this information to devise service interventions or emergency operations in real- time.” Page 44

Download the report (DOC) from Booz Allen Hamilton for FTA or view in Google Docs.

The future of Transit Tracker

Governor Quinn signed legislation this year that requires the remaining Regional Transportation Authority service boards to implement transit trackers of their own. That means by July 1, 2012, Pace and Metra will have a service that provides passengers with real-time departure and arrival information.

The legislation didn’t provide guidance on how Pace and Metra will have to create these services. Advice is  a stone’s throw away: they should consult the experts at CTA in order to create a robust arrival times service that works on many platforms and devices; they should also nurture a developer ecosystem to ensure that the information is broadcast in web and mobile applications.


Mayor Emanuel and Forrest Claypool standing in front of a bus shelter with an LED bus tracker display. Photo by CEI Media Group. 

CTA president Forrest Claypool and Mayor Emanuel announced in Hyde Park on Friday, September 30, 2011, the future installation of 400 LED bus tracker displays inside bus shelters. 150 signs will be installed by March 2012 – view a map of the first locations.

At least one developer is working on the “next generation” of trip planning apps.

Transitflow will be an iPhone app that helps you plan your travel in real-time. According to [Adam] Greenfield, the aim is “to take a step beyond generic journey-planning and timetable apps, and offer people something that will reduce or eliminate the kind of experiential hassles the current generation of interactive services does very little to address.”

It will do this by notifying you of relevant data at various points throughout your journey; for example telling you when to leave your home to catch a train and then, during the journey, advising you in real-time how long it will take to get to your destination. [emphasis added] (ReadWriteWeb)

Suggestions for improvement

I posted a message on the @GridChicago Twitter asking people for their suggestions on how to improve Transit Tracker. Here’s what they came up with:

  • The CTA’s transit trackers should explicitly mention when the next bus is (according to the schedule, even if it’s not coming soon), and when the last bus is (so you can plan to leave to catch that bus or any before it). The Bus Tracker website only shows the next buses up to 30 minutes away. PerilousApricot [The CTA’s website bus tracker will say that “no service is scheduled for this stop at this time”; some app makers give confusing messages for times when there are no upcoming buses or no service.]
  • Post a QR code at each bus stop so people with smartphones can scan and get linked to a webpage with the estimated arrival times. Deprogrammer9
  • Provide historical arrival/departure data. It could be rich for analysis, such as quantifying real differences in commute times before/after service cuts. gensym [This data could also be used to measure travel speeds and congestion levels in different parts of the city.]

How do you think the CTA could improve or expand its bus and train tracking services?


Table 1 – Incoming messages for Bus Tracker by text message

Month Year Messages Rollover Messages Remaining
June 2010 222,675 777,325
July 2010 229,183 1,548,142
August 2010 347,981 2,200,161
September 2010 695,348 2,504,813
October 2010 954,917 2,549,896
November 2010 1,032,805 2,517,091
December 2010 994,930 2,522,161
January 2011 1,321,305 2,200,856
February 2011 1,587,552 1,613,304
March 2011 1,813,785 799,519
April 2011 1,735,321 64,198
May 2011 1,683,952 -619,754
June 2011 1,772,403 -1,392,157


Pew 1 – Americans and Text Messaging.

Pew 2 – Americans and Their Cell Phones.

Pew 3 – Smartphone Adoption and Usage.

*Okay, maybe not – I’ve never asked them myself. I rarely ride transit because I bike around town almost exclusively. Most of my trips this year on transit has been to visit suburbs for bike parking consultations, or to travel in a group to go out on the weekends.

25 thoughts on “The state of transit trackers in Chicago”

  1. I think Bus Tracker, together with the introduction of Chicago Plus card, count as two major ease-of-use improvements CTA introduced over the last decade. I rarely take a bus anymore without checking the expected arrival times first.

    I do notice from my own unscientific observations that Bus Tracker tends to be overly optimistic in arrival times. If it states that a bus will arrive in 10 minutes, it often takes closer to 12 minutes for the bus to arrive at the stop. I am sure that some of that is caused by traffic slowing down the bus, but since all of this is just smart algorithm, I would think it could adjust for time of day and things like traffic, weather, and major events (i.e. Cubs games, street fairs)

    1. It should be adjusting for all of those things because one of the factors of estimating the arrival time is polling where the bus is currently and where it was recently (from which you gauge speed). If you think there’s a particularly bad consistency on a route or at a bus stop you could email with some information and they will take a look. 

  2. Somewhat related, it would be nice if the CTA was more specific about service times for their routes on bus stop signs?  When is late evening anyways?

    1. I surmise they leave it purposefully vague. They do print schedules on paper that you can get at various locations (actually, I have no idea where, or even if they still print these). When they leave it vague, it makes it easier for them to change the schedule without having to change the sign. So if the last bus arrives at 7:34 PM and they institute a service reduction on that bus route, and the last bus arrives at 7:23, then “late evening” still applies. 

  3. I don’t have a smart phone, so I use CTA by text. It hasn’t worked in a week for me. Not sure what is going on!

  4. While many of the CTA’s improvements for transit tracking have been great, I suggest a more useful and cost effective solution for train stations.

    Instead of getting train estimations once you’re on the platform (which are sometimes not updated or displayed) The CTA should install three colored lights at street level which are visible from a distance. Let’s say light number 1 means > 5 minutes to a train. Light number 2 means 2-5 minutes to train. light number 3 means approaching/hurry up.

    This may be complicated by the presence of multiple train lines at one station and would not be overly helpful for visitors, we’ll let the people who get paid figure out these issues. However, the well-seasoned L rider would gain useful information while on the street level. Additionally, I estimate this would cost so much less than putting in LED displays for bus shelters that display info which is readily available via text.

    Adding text codes for train stations (similar to the ones displayed on bus signs) would also be stellar.

    1. I like this idea, but it doesn’t allow for trip planning for people who aren’t yet on the street. I doubt that this will be MORE cost effective than the online and SMS transit trackers. It may be equally or less cost effective. By creating and nurturing the developer ecosystem, the CTA’s “little work” on working with its Bus Tracker and Train Tracker vendors to create APIs grows exponentially because app developers take charge on spreading that information to the public, giving the CTA a wider reach than it could make itself. 

      For example, because of its Customer Service Alerts API, there are 8 Twitter accounts you can follow that automatically post alerts issued by the API. If you want alerts automatically sent to you about the Blue Line, follow @ctablue. The CTA didn’t create the Twitter account; the cost of creating a Twitter alerts (a developer’s time, mostly) was borne by the developer. 

  5. I think there is a typo in the SMS costs.  The article states that the CTA pays $3,500 / month for one million text messages, which is .35 cents per text message, not 3.5 cents.

    1. Uh, I don’t know how it happened. I’ve killed the three theories I’ve come up with in the past 10 minutes because they don’t hold much water. So I’ll just throw some short questions to you: Different priorities? Available funding? High train frequency that doesn’t merit a train tracking system? The oldness of CTA versus the newness of Metro/WMATA?

  6. the SMS bus tracker is very nice and very useful – however, for it to remain useful, CTA bus signs that get knocked over/removed for street work/otherwise go missing need to be replaced quickly.  the NB 53 bus stop at ohio/pulaski has been without a sign for most of the year – it was taken out by a careening car in january (i saw that, it was pretty sweet), was replaced in like june, and then was removed again for street/sidewalk repairs.

    likewise, the NB 151 stop at sheridan/broadway has an older-generation bus stop sign without the code to message. 

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