Interpret with care
What this explorer measures
This explorer compares CMS dialysis-facility records,
geocoded through the U.S. Census Bureau, with fixed-route
stops loaded from the USDOT/BTS National Transit Map using
geodesic straight-line distance. It displays up to the three
closest eligible stops per visible facility and shows a
shared stop only once.
Transit filters can search loaded stop names or IDs and narrow
candidates by stop type, wheelchair indication, or agency/NTD
ID. An optional radius filter keeps only selected stops within
the active proximity threshold. Candidate and displayed-stop
counts update with the filters.
The optional transit-distance heatmap colors every visible,
filtered dialysis facility by its distance to the nearest
eligible transit stop. At low zoom it uses the published
nationwide nearest-stop snapshot; at zoom 10 or closer it
switches to eligible stops selected from the active viewport.
Relative mode divides the visible nearest-stop distance scale
into five bands. Meter-range mode applies four user-defined
cutoffs directly to the nearest-stop distance. Both modes run
from green through green-yellow, yellow, and yellow-red to red.
- Facility model
- CMS Provider Data Catalog fields
- Transit model
- USDOT/BTS National Transit Map fields
- Geocoding model
- U.S. Census Geocoder statuses
- Data prepared
- Loading source manifest…
Source limitations represented by the final product
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CMS listings can include facilities with changed operating
status or availability.
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National Transit Map coverage and source validity vary by
agency and snapshot.
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National Transit Map data support research—not navigation or
real-time trip planning.
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Address-range facility coordinates are approximate, and
unresolved records remain visible in the table.
Proximity does not measure schedules, walking barriers,
safety, weather exposure, disability access, paratransit
eligibility, or trip feasibility.
Accessibility
The project targets WCAG 2.2 AA for the non-map interface.
Controls are keyboard accessible, focus is visible, layer
changes are announced, reduced-motion preferences are
respected, and analytics have text and table equivalents.
Alternatives to map exploration
The Analytics tab provides a sortable table on larger
screens and cards on smaller screens. Broad national results
are capped in the visible table for performance; state
selection, map navigation, and filters narrow the
population, while CSV export contains the complete current
filtered result with provenance fields.
The transit-distance heatmap is optional and supplementary.
Its legend provides text labels for all five distance bands
and either the relative endpoints or fixed meter ranges.
Visible facility marker descriptions also state the
nearest eligible transit-stop distance, so color is not the
only cue.
Transit filter availability, active-filter totals,
candidate matches, and displayed-stop totals are exposed as
text. Every transit control has a programmatic label and is
disabled while viewport candidates are unavailable.
Known limitation
Third-party map tiles and controls have accessibility
characteristics governed by Google Maps Platform. The map
is supplementary; it is not the only way to reach facility
results.
Privacy
Location
Location access occurs only after you select “Use current
location” and approve the browser prompt. The site uses the
result to move the map and does not save or transmit it to
an application server.
Third-party services
The basemap uses Google Maps Platform. Street-level map
views request transit stops for the visible geographic
bounds from the USDOT/BTS ArcGIS service. Those services
are subject to their respective privacy terms. CMS facility
and Census-geocode records are served from the published
site snapshot.
Terms of use
The Dialysis & Transit Explorer is an educational research
tool. It uses public CMS facility records, U.S. Census
address-range geocodes, and USDOT/BTS National Transit Map
stop records.
No care or transportation advice
Straight-line proximity does not establish that a transit
trip is available, accessible, safe, timely, or feasible.
Do not use this explorer for patient care, emergency
decisions, trip planning, provider selection, or service
eligibility.
Data and service availability
The site is provided as-is without a warranty of accuracy,
completeness, fitness, or uninterrupted availability.
Google Maps content remains subject to Google Maps Platform
terms. Source data can contain omissions, stale records,
approximate coordinates, and incomplete transit coverage.
CMS, Census Bureau, USDOT/BTS, and Google attribution must
be preserved.
by Micah Etter, MD