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Independent reporting and explainers for the people who publish, integrate, specify, and govern mobility data.
Read the lead briefing25entries
Current desk
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Transit agencies have had to report cyber events to the National Transit Database for years, and the database holds nine of them. We pulled every one, and read the 2025 clarifications meant to close the gap.
Read the briefingInteroperabilityExplainer
The Mobility Data Interoperability Principles define an open standard with five tests. A new registry grades 55 specifications against them. We counted the verdicts: free and documented is common, open governance is not, and passing all five does not make a standard adopted.
Feeds & StandardsRoundup
What moved on the transportation data layer from early September to early October 2026: Google hands GTFS ownership to MobilityData, shapes.txt becomes conditionally required, the canonical validator picks up five unreleased rules, and the licence proposal's first vote closes with the result pending.
Quality & ComplianceExplainer
MobilityData's canonical validator has 181 notice codes, three severities, and one word that matters for compliance. We ran 736 live US feeds through it and read four years of California's monthly reports to see what actually fails.
Agency ITExplainer
The box on the bus, the console in the control room, and the one message that leaves the building. We polled 92 open US vehicle-position feeds to see what a location report really carries and how old it is.
Feeds & StandardsExplainer
GTFS-Realtime says where the bus is now. TIDES is the eleven-table format for where it was, who boarded, and what they paid, once the service day is over. We counted the spec and read the one public dataset.
Feeds & StandardsExplainer
The GTFS feed an agency publishes stops at the first revenue stop. TODS is the ten-file extension that adds the pull-outs, deadheads, crew runs, and vehicle assignments behind it, so a scheduling system can hand a day's work to CAD/AVL without a custom export.
Feeds & StandardsRoundup
What moved on the transportation data layer from early August to early September 2026: two GTFS merges on the same day, MDS 2.1 emergency zones prototyped in Seattle, and three proposals in the queue that would change what a feed carries.
InteroperabilityExplainer
OpenStreetMap mappers have already placed most of the objects an agency wants to contribute, and placed them well. What the map lacks is the agency's own IDs, which is the one thing only the agency can supply.
Feeds & StandardsExplainer
GTFS-Flex has been part of the core specification since March 2024, and the validator polices it with 29 dedicated checks. We read every feed in the Mobility Database to see how many agencies actually use it.
Agency ITReport
The gate opens before anyone has checked whether the card works. Here is the back office behind contactless transit fares: deny lists, aggregation, deferred authorization, and why most 2026 launches shipped at adult full fare only.
Quality & ComplianceRoundup
What moved on the transportation data layer from mid-July to early August 2026: FTA's Transit Moves America dashboard, a federal question about whether real-time data counts as service quality, the MDS 2.1 release, and two new GTFS-Realtime alert fields.
Feeds & StandardsExplainer
Three specifications cover the same scooters, bikes, and delivery vans, and practitioners routinely pick the wrong one. Here is what each was built to answer, why MDS requires a public GBFS feed, and where the boundary between them actually falls.
AI in TransportationExplainer
Transit agencies are running machine learning in production today, but not in the places the marketing points to. Here is what the working deployments have in common, and why the ones that stall usually stall on data rather than on models.
Agency ITRoundup
What moved on the transportation data layer from mid-June to mid-July 2026: World Cup open-loop fare launches, new National Transit Database reporting rules, MDS 2.1 in preview, and AI landing in agency software.
Feeds & StandardsExplainer
GTFS is the open format that puts transit schedules into your maps app. Here is what a feed contains, how its files join together, and why it became the default for transit data worldwide.
Feeds & StandardsExplainer
GTFS-Realtime is the standard for live transit data: what a feed carries, how Protocol Buffers structure it, and why the quality rests on the systems behind it.
InteroperabilityExplainer
Intelligent transportation systems is a broad label that hides a precise idea. What ITS covers, what it looks like on the street, and why 253 of the 304 standards in the national architecture are about nothing but getting data from one system to another.
InteroperabilityExplainer
Transit signal priority lets a late bus ask a traffic signal for a few more seconds of green. Here is the request-to-grant message chain, how it differs from emergency preemption, and how NTCIP 1211 lets mixed-vendor buses and controllers interoperate.
Data PlatformsExplainer
Mobility as a service promised one app to plan, book, and pay for every trip on a subscription. The flagship consumer bundle went bankrupt. Here is what the idea got right, what it got wrong, and which pieces survived.
Quality & ComplianceExplainer
Three buses arriving nose to tail is not bad luck. It is a feedback loop in frequent service, where a late bus falls further behind and the one behind it catches up. Here is the mechanism, why agencies measure headway instead of schedule, and what they do about it.
Quality & ComplianceExplainer
A ghost bus is a prediction with no vehicle behind it. Here is how a transit app generates one, the four ways it happens, and how Chicago drove its rate down.
Feeds & StandardsExplainer
The countdown on the sign is a prediction, not a readout of a bus you can see. Here is the data chain behind it, from the vehicle's GPS to the feed the sign reads, and the three ways agencies turn location into a time.
Quality & ComplianceExplainer
The NTD is the federal record of US public transit: who rides, what it costs, and who has to report. Here is what it holds, who files it, and how to pull the numbers yourself.
Agency ITExplainer
Agencies are moving fare logic off the card and into a back office. Here is what account-based ticketing, fare capping, and open-loop payment each mean, and which agencies have made the switch.
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