How BarTrakr maps coverage
Where the data comes from, how a coverage map is built, and what it can and can't tell you.
Data sources
- Rail alignment: U.S. Department of Transportation, Bureau of Transportation Statistics, National Transportation Atlas Database (NTAD), Amtrak Routes layer.
- Mobile coverage: Federal Communications Commission, Broadband Data Collection (BDC), mobile broadband coverage by provider and technology, downloaded per state from the National Broadband Map.
- Basemap: OpenFreeMap vector tiles built from © OpenStreetMap contributors.
Coverage classes
- Fast 5G — 5G NR modeled at 35 Mbps down / 3 Mbps up
- 5G — 5G NR modeled at 7 Mbps down / 1 Mbps up
- LTE — 4G LTE modeled at 5/1 Mbps
- Spotty — undefined
- No coverage — No modeled coverage from this carrier in the processed FCC layers
- No data — A stretch our pipeline has not classified yet. This is a processing gap, not a claim of no service.
Each stretch of track gets the best technology that covers it.
On the train vs. outdoor
Carriers model two environments for the FCC: in-vehicle mobile (inside a moving vehicle) and outdoor stationary (standing still outside). The in-vehicle area is the strong core of each network; the outdoor area adds a weaker fringe around it.
The default "On the train" view combines them. Stretches inside the in-vehicle area are shown in color as solid coverage. Stretches only inside the outdoor fringe are shown in amber as spotty, because riders often still get signal there (we've confirmed 5G on board in areas the in-vehicle model leaves out), but it can drop. Only stretches outside both models are red dead zones. The Outdoor switch shows the outdoor model on its own, which is useful at station stops.
Stretches shorter than a quarter mile are merged into their neighbors. At train speed they last only seconds.
How a route is built
- Download the FCC coverage files for each carrier, technology and state the route crosses.
- Extract the route's alignment from NTAD and project it to a common coordinate system.
- Sample the line at short intervals and intersect it with each coverage layer. Each stretch takes the best matching technology.
- Reconcile state boundaries and overlapping polygons so every mile is classified, using “no data” wherever input is missing.
- Measure everything by distance along the track, then compute route and station-to-station statistics.
- Publish a compact file per route with the line and coverage runs for each carrier, keyed to mileposts.
Live tracking and privacy
“Track my trip” uses your device's GPS through your browser. GPS doesn't need a cell signal, so tracking keeps working in dead zones. Your position is matched to the route on your device. BarTrakr doesn't send or store your location.
Limitations
- FCC mobile coverage is modeled by carriers, not measured. Real signal inside a steel railcar is usually weaker.
- Coverage changes as towers are built and networks are upgraded. Each route page shows its data release date.
- Modeled coverage says nothing about speed under load, latency or capacity on a crowded train.
- Wi-Fi on Amtrak uses cellular backhaul, so it generally follows the same gaps.
Independence
BarTrakr is an independent project of Mile Marker 22. It is not affiliated with, endorsed by or sponsored by Amtrak, the FCC, the U.S. DOT or any wireless carrier. Carrier names are used only to identify the data shown.