Desk
Quality & Compliance
Validation, conformance, feed health, and reporting such as NTD and SB125.
06entries
On this desk
Explainers
Explainer
NTD cybersecurity reporting: why the database holds only nine transit cyberattacks
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.
Explainer
What the GTFS validator actually checks, and why feeds still fail
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.
Roundup
August 2026 roundup: the NTD goes public, MDS 2.1 ships, and alerts get a clock
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.
Explainer
Bus bunching and headway: why three arrive at once
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.
Explainer
Ghost buses: why the app shows a bus that never comes
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.
Explainer
What the National Transit Database actually holds
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.