1001 Smart Cities
🇺🇸 Chicago

CTA Bus Tracker, Train Tracker & the Developer Feeds

🤖 AI-generated summary · ◆ 1 sourced claim · 🔎 Last verified

This overview was generated with AI from the public sources listed below and checked against them before publication. It has not had a complete human fact-check — treat it as a starting point and follow the sources.

1 sourced claim on this page, none individually verified yet — turn on “Sources in the text” to see each one.

How this atlas is made · What “last verified” means · What “source-checked” means · The full record behind this page

✎ Corrected 20 Aug 2026 Publication date recorded for 1 source. What changed →

The sharpest use of the CTA's feed was against the CTA: volunteers scraped it from May 2022 to count buses that were scheduled and never ran. Since May 2025 the agency publishes its own cancellations.

Outcome🔄 Ongoing
Evidence🔬 Peer-reviewed
what does this mean?The strongest source behind this entry is an independent peer-reviewed or academic study. It grades who did the looking — not how well the project went. All four grades →
Run byChicago Transit Authority (CTA)
Scale🏙️ City-wide

Part of 1001 Smart Cities — 1,167 documented projects · 🏙️ 7 more in Chicago · 📊 Open data guide · 📡 Data & IoT projects

The CTA started tracking buses on one route, #20 Madison, on 5 August 2006, covered the fleet by May 2009 and added Train Tracker in January 2011. Riders now meet the predictions largely inside other people's apps: the agency publishes Bus Tracker, Train Tracker, alert and GTFS-Realtime feeds, each behind a free registered key. The licence is not an open one — revocable, limited to uses that assist transit riders, and barring anyone from selling the data apart from their app. The feed's sharpest use was against the CTA itself: volunteers scraped it from May 2022 to count buses that were scheduled and never ran. Since May 2025 the agency publishes its cancelled runs, so apps can strike them out.

Live 📅 since 2006

📊 Impact

A peer-reviewed study of route-level ridership across the staged 2006-2009 rollout found Bus Tracker did raise CTA bus ridership, though 'the average increase is modest' (Tang & Thakuriah, Transportation Research Part C, 2012). The CTA reported running 98.8% of scheduled buses and 88% of scheduled trains in June 2025.

🎓 Lesson

Opening the feed let riders audit the service with it: the same data that promised a bus was used to prove the bus never came, and the agency ended up publishing its own cancellations. The licence, however, is a bespoke revocable grant, not an open one.

📡 Data & IoTOpen dataPublic transportSensors & IoT

Sources

↗ CTA Developer Center — open Chicago transit data (operator) archived copyLists the Bus Tracker API, Train Tracker API, Customer Alerts API, GTFS schedule data and the GTFS-Realtime feeds, each requiring a free registered developer key. Direct fetch from this environment returned 403; contents confirmed through the indexed CTA sub-pages, incl. the Train Tracker key application form. The Train Tracker developer guide (PDF, not renderable here) is the origin of the circulating default limit of 100,000 transactions per day — deliberately not asserted in the entry.
↗ CTA Developer License Agreement and Terms of Use (operator) archived copyThe licence, verified verbatim from a mirrored copy at openmobilitydata-data.s3-us-west-1.amazonaws.com/public/feeds/chicago-transit-authority/165/20150206/original/developers_license_agreement.htm: a 'limited, non-exclusive, non-assignable, non-transferable and revocable license'; data 'may not be used, in whole or in part, for any other purpose' than assisting riders or promoting public transportation; 'You will not sell, auction or barter any CTA Data separate from your application.' Attribution is explicitly optional. Data is supplied 'AS IS' with no representation as to accuracy or completeness.
↗ Tang & Thakuriah — Ridership effects of a real-time bus information system: a case study in the City of Chicago (peer-reviewed)Published June 2012 archived copyTransportation Research Part C 22 (2012), 146-161. Uses the staged 2006-2009 rollout as a natural experiment on route-level monthly weekday ridership, January 2002 to December 2010. Abstract read at worldtransitresearch.info/research/4150/: 'the provision of Bus Tracker service does increase CTA bus ridership, although the average increase is modest.' The per-route trip figures circulating in secondary reports were not confirmable against the paper and are not used.
↗ Chicago Sun-Times — Chicago 'ghost buses' may be a thing of the past as CTA shares new data with transit apps (4 Aug 2025) archived copyThe consequence: the CTA began sharing cancelled runs on 1 May 2025 so they no longer appear as scheduled buses; Transit adopted it days later, Ventra, Google Maps and Apple Maps to follow. Carries the CTA's June 2025 delivery figures — 98.8% of scheduled buses, 88% of scheduled trains — and weekday ridership at about 69% of 2019.
↗ Chi Hack Night — Ghost Buses project archived copyCivic-tech group formed spring 2022, project page November 2022. Scrapes the CTA Bus Tracker getvehicles feed every five minutes and compares it with the CTA's own GTFS schedule; collection began 20 May 2022. The clearest case in the atlas of an agency feed used to audit the agency.
Show 4 more sourcesShow fewer
↗ Mansueto Institute for Urban Innovation (University of Chicago) & Chicago Tribune — CTA Stop WatchIndependent analysis of over 100 million real-time bus locations from the Ghost Buses archive, June 2022 to July 2024: 'The CTA initially decreased scheduled service in early 2022 through 2023 to match the slower real-time performance and later increased it in early 2024.' Metrics include excess wait time and actual versus scheduled buses by community area.
↗ Grid Chicago — The state of transit trackers in Chicago (2011) archived copyChronology: pilot 5 August 2006 on route 20/Madison, thirteen routes by March 2008, last routes May 2009, Train Tracker 8 January 2011. Also records the sequence behind the API — a Chicago developer reverse-engineered the Bus Tracker feeds before the CTA formally released one. No launch date for the official API is given here or in any source found, so none is claimed.
↗ US DOT ITS Knowledge Resources — CTA bus arrival prediction accuracy archived copySummarising the FTA-sponsored 'Traveler Information Systems and Wayfinding Technologies in Transit Systems' (2 May 2011): 'As a result, the Chicago Transit Authority (CTA) has a 92% accuracy rate for bus arrival prediction.' Self-reported by the CTA and relayed by a federal state-of-practice review, not an independent audit — recorded here rather than in the impact field. No independent evaluation of CTA prediction accuracy was found.
↗ Mobility Database — Chicago Transit Authority GTFS schedule feed archived copyCurrency check: feed listed Active, service window beginning 7 July 2026, quality report last updated 11 July 2026.
Show your work What this page rests on and what it can’t tell you · all 1 claims with their sources · the forensic record

Evidence Passport · public beta 1 addressable claim, 9 source dossiers, one permanent baseline. The passport is unreviewed — an AI-assisted structural migration, not a human or expert endorsement. Every revision keeps a permanent copy under revision history.

Inspect the claims, one by one — verbatim text, sources and caveats for all 1

The text below is copied verbatim from the published record. Each claim names the source dossiers that carry it; caveats stay attached to the claim they qualify.

Claim 1 clm-b62dd1cf01ab9e1a quantitative
A peer-reviewed study of route-level ridership across the staged 2006-2009 rollout found Bus Tracker did raise CTA bus ridership, though 'the average increase is modest'
Published field
impact · verbatim
Mapping
mapped · no interpretation or interpolation added by this passport
What the mapping says
The impact cites the study as Tang & Thakuriah, Transportation Research Part C, 2012.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Tang & Thakuriah — Ridership effects of a real-time bus information system: a case study in the City of Chicago (peer-reviewed)
Forensic record — source dossiers, gaps, hashes and the exact revision this page renders

This layer records what is known about each source, what is still missing, and the exact snapshot this page is rendering. A missing date, archive or hash stays visible as missing.

unreviewed Revision 2026-08-20-source-dates-corrected effective 2026-07-26 · created 2026-08-20

Awaiting operator and domain-expert review; publication of this revision implies neither.

sha256:bc4c5224f92d0939bc4b94e4da926364e354bb9227483930016fa8987213a29e
Revision history → Permanent version link → Machine-readable record → Evidence Constitution →
1
of 1 claims mapped
9
source dossiers
1
publication dates recorded
1
archives linked
0
exact locators
0
content captures hashed

Governance facts carried by the record

Operator
Chicago Transit Authority (CTA)
Actor types
utility
Funding model
public
Funding description
Not recorded
Cost
Not recorded
Ownership
Not recorded
Decision rights
Not recorded
Exit conditions
Not recorded

9 source dossiers

CTA Developer Center — open Chicago transit data (operator) transitchicago.com · background

Open original source ↗

Stable source ID
src-1f9a4f6718b97f74
Publisher
Name not classified · transitchicago.com
Type / language
web-page · language not classified
Published
Not recorded
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-07-26
Dossier created
2026-08-20
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Lists the Bus Tracker API, Train Tracker API, Customer Alerts API, GTFS schedule data and the GTFS-Realtime feeds, each requiring a free registered developer key. Direct fetch from this environment returned 403; contents confirmed through the indexed CTA sub-pages, incl. the Train Tracker key application form. The Train Tracker developer guide (PDF, not renderable here) is the origin of the circulating default limit of 100,000 transactions per day — deliberately not asserted in the entry.

Descriptive only — not page/paragraph exact
Claims linked
Background source; no baseline claim points here
CTA Developer License Agreement and Terms of Use (operator) transitchicago.com · background

Open original source ↗

Stable source ID
src-d6103403e35129a7
Publisher
Name not classified · transitchicago.com
Type / language
web-page · language not classified
Published
Not recorded
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-07-26
Dossier created
2026-08-20
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

The licence, verified verbatim from a mirrored copy at openmobilitydata-data.s3-us-west-1.amazonaws.com/public/feeds/chicago-transit-authority/165/20150206/original/developers_license_agreement.htm: a 'limited, non-exclusive, non-assignable, non-transferable and revocable license'; data 'may not be used, in whole or in part, for any other purpose' than assisting riders or promoting public transportation; 'You will not sell, auction or barter any CTA Data separate from your application.' Attribution is explicitly optional. Data is supplied 'AS IS' with no representation as to accuracy or completeness.

Descriptive only — not page/paragraph exact
Claims linked
Background source; no baseline claim points here
Tang & Thakuriah — Ridership effects of a real-time bus information system: a case study in the City of Chicago (peer-reviewed) sciencedirect.com · 1 linked claim

Open original source ↗

Stable source ID
src-a310fc2668d0d9ab
Publisher
Name not classified · sciencedirect.com
Type / language
web-page · language not classified
Published
Not recorded
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-07-26
Dossier created
2026-08-20
Retrieved copy
No local capture recorded
Archive
Open archived copy ↗ · 2024-04-20
Content hash
No captured content hash
Locator
Open the recorded source note

Transportation Research Part C 22 (2012), 146-161. Uses the staged 2006-2009 rollout as a natural experiment on route-level monthly weekday ridership, January 2002 to December 2010. Abstract read at worldtransitresearch.info/research/4150/: 'the provision of Bus Tracker service does increase CTA bus ridership, although the average increase is modest.' The per-route trip figures circulating in secondary reports were not confirmable against the paper and are not used.

Descriptive only — not page/paragraph exact
Claims linked
Chicago Sun-Times — Chicago 'ghost buses' may be a thing of the past as CTA shares new data with transit apps (4 Aug 2025) chicago.suntimes.com · background

Open original source ↗

Stable source ID
src-9c4df3507eb41ebe
Publisher
Name not classified · chicago.suntimes.com
Type / language
web-page · language not classified
Published
2025-08-04
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-07-26
Dossier created
2026-08-20
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

The consequence: the CTA began sharing cancelled runs on 1 May 2025 so they no longer appear as scheduled buses; Transit adopted it days later, Ventra, Google Maps and Apple Maps to follow. Carries the CTA's June 2025 delivery figures — 98.8% of scheduled buses, 88% of scheduled trains — and weekday ridership at about 69% of 2019.

Descriptive only — not page/paragraph exact
Claims linked
Background source; no baseline claim points here
Chi Hack Night — Ghost Buses project chihacknight.org · background

Open original source ↗

Stable source ID
src-d70829cb245b1010
Publisher
Name not classified · chihacknight.org
Type / language
web-page · language not classified
Published
Not recorded
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-07-26
Dossier created
2026-08-20
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Civic-tech group formed spring 2022, project page November 2022. Scrapes the CTA Bus Tracker getvehicles feed every five minutes and compares it with the CTA's own GTFS schedule; collection began 20 May 2022. The clearest case in the atlas of an agency feed used to audit the agency.

Descriptive only — not page/paragraph exact
Claims linked
Background source; no baseline claim points here
Mansueto Institute for Urban Innovation (University of Chicago) & Chicago Tribune — CTA Stop Watch github.com · background

Open original source ↗

Stable source ID
src-de963b61597ab024
Publisher
Name not classified · github.com
Type / language
web-page · language not classified
Published
Not recorded
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-07-26
Dossier created
2026-08-20
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Independent analysis of over 100 million real-time bus locations from the Ghost Buses archive, June 2022 to July 2024: 'The CTA initially decreased scheduled service in early 2022 through 2023 to match the slower real-time performance and later increased it in early 2024.' Metrics include excess wait time and actual versus scheduled buses by community area.

Descriptive only — not page/paragraph exact
Claims linked
Background source; no baseline claim points here
Grid Chicago — The state of transit trackers in Chicago (2011) gridchicago.com · background

Open original source ↗

Stable source ID
src-e7ee9eea3fa7ebcd
Publisher
Name not classified · gridchicago.com
Type / language
web-page · language not classified
Published
Not recorded
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-07-26
Dossier created
2026-08-20
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Chronology: pilot 5 August 2006 on route 20/Madison, thirteen routes by March 2008, last routes May 2009, Train Tracker 8 January 2011. Also records the sequence behind the API — a Chicago developer reverse-engineered the Bus Tracker feeds before the CTA formally released one. No launch date for the official API is given here or in any source found, so none is claimed.

Descriptive only — not page/paragraph exact
Claims linked
Background source; no baseline claim points here
US DOT ITS Knowledge Resources — CTA bus arrival prediction accuracy itskrs.its.dot.gov · background

Open original source ↗

Stable source ID
src-ab5788b0091a853f
Publisher
Name not classified · itskrs.its.dot.gov
Type / language
web-page · language not classified
Published
Not recorded
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-07-26
Dossier created
2026-08-20
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Summarising the FTA-sponsored 'Traveler Information Systems and Wayfinding Technologies in Transit Systems' (2 May 2011): 'As a result, the Chicago Transit Authority (CTA) has a 92% accuracy rate for bus arrival prediction.' Self-reported by the CTA and relayed by a federal state-of-practice review, not an independent audit — recorded here rather than in the impact field. No independent evaluation of CTA prediction accuracy was found.

Descriptive only — not page/paragraph exact
Claims linked
Background source; no baseline claim points here
Mobility Database — Chicago Transit Authority GTFS schedule feed mobilitydatabase.org · background

Open original source ↗

Stable source ID
src-8a2fce3a88189f13
Publisher
Name not classified · mobilitydatabase.org
Type / language
web-page · language not classified
Published
Not recorded
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-07-26
Dossier created
2026-08-20
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Currency check: feed listed Active, service window beginning 7 July 2026, quality report last updated 11 July 2026.

Descriptive only — not page/paragraph exact
Claims linked
Background source; no baseline claim points here
Known limits of this passport
  • Publisher names and source languages have not yet been classified; domains are recorded without guessing.
  • Existing source notes are descriptive locators, not page- or paragraph-exact citations.
  • A missing archive, publication date or content hash is shown as null rather than inferred.
  • The project-level evidence grade ranks the strongest source in the entry; it is not a truth score for every claim.

Continue exploring

Compare this project

🇺🇸 NextMuni: Real-Time Muni Predictions & the Fight Over Who Owned Them · San Francisco San Francisco fought the same licence question: a licensee claimed its predictions, and the city wrote ownership into the contract. 🇺🇸 Chicago's Open Data Executive Order and Portal · Chicago Both were audited from outside: the OIG found the portal's reports had stopped, volunteers used this feed to count buses that never ran. 🇮🇳 BMTC Bus Tracking and Open Transit Data · Bengaluru Same workaround, different reason: Bengaluru's developers scrape the operator's app for a GTFS; Chicago's scraped this feed to audit it.

Explore the wider context

🌍 Hardware Stops, Data Doesn't📖 GTFS (General Transit Feed Specification)📖 Open data📖 Urban data platform (UDP)
📎 Cite this project

1001 Smart Cities (2026). “CTA Bus Tracker, Train Tracker & the Developer Feeds” — Chicago, United States. The Smart City Atlas. https://1001smartcities.org/projects/chicago-cta-tracker/ (last verified 2026-07-26). Data: CC BY 4.0.

The underlying data is free to reuse with attribution — see the open data page.

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