A physical network diagram database for the New York City subway system, covering Division A (IRT), Division B1 (BMT), and Division B2 (IND). Station data is organised by line chain and build route, with engineer's chain distances, build era, CBTC status, and station setup type.

Data compiled from NYCT Signal and Engineering prints, NYCTA Engineering Guidelines Volumes 1 and 2, NYCT route and section documents, and NYCT Draw. Build and construction data are also pulled from RTC, PSC, BOT, TA, and MTA records, documents, and annual reviews. Chain distances based on the engineer's chain notation (1+00 = 100 ft), measured from the north end of each station.

The Subways.io Diagram Database documents the NYC subway as physical infrastructure — every station, every line chain, every construction route across the three operating divisions: A (IRT), B1 (BMT), and B2 (IND). Navigate using the five views in the left sidebar, or via the bottom navigation on mobile.

Line Key  — the default landing view. The complete list of all 49 active line chains across the three divisions (plus a Historical filter for transferred and retired chains), with chain zero (the datum point), direction, and station count. Tap any chain to drill into its station list. Switch to Map to see every chain at once, each in its own shade of its division’s colour, with the same division and Historical filters; hover or tap a chain to highlight it and open its card.

Chain  — the station list for the current chain. Each station shows its marker (engineer's chain notation, e.g. 624+50), opening year, setup type code, and era. Tap a station to open its full detail card. Use the chain list in the sidebar (dedicated row on mobile) to switch between chains in the current division.

Route  — opens the Route Key, a system-wide table of all 66 construction routes — IRT contracts, numbered routes, capital projects, and BRT-era private routes. Each row shows the route's corridor name, line chains, divisions, contract code, and assigned services (the colored bullets). Filter by division at the top. Tap any route to view its station list, organized by build section. Dimmed routes indicate no station data is mapped yet.

Crossings  — water crossings system-wide. East River, Harlem River, Newtown Creek, Beach Channel, Flushing River, and others. Each entry shows the structure type, approach grade, division, and year opened.

Yards  — the 22 storage and maintenance yards across the system. Each entry shows the division, connected line chains, borough, year opened, capacity in trains and cars, and whether the yard has a shop, car wash, refuse, or work-train facilities.

Click the Search field in the top bar (or press ⌘K / Ctrl+K) to open the global search modal. Type any part of a station name or route — results show inline with division and chain badges, with the matched text highlighted. Use the arrow keys to navigate, Enter to open the selected result.

Tap any station in a chain or route list to open its full detail card. The marker at the north end (engineer's chain notation: 1+00 = 100 ft from chain zero) heads the card, followed by four sections:

Identity — Division, borough, former names, opening year and rebuilds, build era, and the predecessor railroad where one existed.

Chaining — Chain zero (the datum point for measurements), the marker, the computed distance from chain zero in feet and miles, route designation and section, and track count.

Structure — Station type, setup (Elevated, Underground, etc.) with its code (E1–E4, U1–U6, G1–G4, X1–X3), platform configuration and code (P1–P6), MOW type, thoroughfare width, terminal type (Reverse, Relay, Layup, etc.), ADA status, and the Platform Lengths and Platform Geometry sub-sections.

Signalling — CBTC status and, for the A-division, ATS-A status.

Notable / Notes — Exceptional engineering characteristics and supplementary notes, in the gold-bordered cards at the foot.

On the Stations tab in Chain mode, the Table / Map switch at the right end of the tabs row swaps the station table for a map of the same chain. The selected chain is drawn in blue with every other chain dimmed behind it for context; station markers follow the Route, Era and Setup filters, so the map always shows the same stations as the table. Click a marker to open its station card, or open a card from the table and switch to the map to see where it sits. Hover a marker for the station's marker, opening year and construction route and section; the selected station keeps that box pinned in gold. The chain draws in the build-era colours of the printed diagram's Era Map Key (hue is the division, shade is the era; a legend sits under the layer list) with the chain letter labelled along it; where stations record a construction section, the section is labelled along the line in smaller text (a layer toggle turns these off). Hollow gold markers are closed or hand-placed stations whose position is approximate. The 3D buildings layer tilts the map and extrudes buildings to their real heights; it is off by default and reads best zoomed in on a single station. Chain lines currently join stations point-to-point rather than following the track. The map state is part of the page link, so a shared link opens in the same view.

In Chain mode, two filter chips sit at the right end of the tabs row, after the route chips: Era and Setup. Tap a pill to open a dropdown of values present in the current chain, each with a station count. Selections are multi-select within a pill (OR logic) and AND-combined across pills — e.g., (era = BOT OR Dual Contracts) AND (setup = U1 OR U2). Active filters get a gold outline on the chip. Clear all filters with the Clear ✕ button.

The Division switcher (A — IRT, B1 — BMT, B2 — IND, All) in the top bar scopes the visible chains. In ALL mode, chains from every division are shown together.

Some routes were built across two divisions (e.g., Route 5 — Broadway & Lexington spans A and B1). In the route detail view for these routes, the static division tag is replaced with switchable division pills. Tap a pill to view that division's segment of the route. The current division is filled with the division's color (red A, blue B1, green B2).

CBTC dot — In every station list and on the station card, the CBTC dot indicates Communications-Based Train Control status:

   Active (e.g., L line, 7 line)

   In progress

   Not active

Territory rail — the coloured bar down the left edge of the station list shows the extent of CBTC territory, not just its edges:

    Solid green — CBTC in service

    Dashed yellow — being installed, not yet cut over

The rail is capped with a short bracket where live CBTC meets conventional block signalling — that cap is the transition point. There is no cap where an installation runs into existing CBTC, because that is one territory being extended rather than two meeting, and none at the ends of a list, where what lies beyond is off screen. Stations with no recorded CBTC status carry no rail and do not cap a run.

ATS-A row (A-division only) — Automatic Train Supervision for the IRT. All A-division stations on chains other than C and CC are under Siemens ATS-A supervision. The B-division skipped ATS-B and went directly to CBTC, so B-division station cards don't show an ATS row.

The colored circles in the Route Key represent train services using the MTA's standard color palette:

1 2 3  Red — Broadway / 7th Ave local & express   4 5 6  Green — Lexington Ave   7  Purple — Flushing   A C E  Blue — 8th Ave   B D F M  Orange — 6th Ave   G  Light green — Crosstown   J Z  Brown — Nassau Street   L S H  Gray — Canarsie & shuttles   N Q R W  Yellow — Broadway BMT

For full term definitions, open the Glossary from the top bar. Quick reference:

Setup types — E1 standard steel elevated · E2 high elevated / viaduct · E3 concrete elevated · E4 dual-level elevated · U1 shallow cut-and-cover · U2 deep cut-and-cover · U3 mined / rock station · U4 bored / tube station · U5 deep bore · U6 dual-level underground · G1 at grade · G2 embankment · G3 open cut · G4 retained cut / trench · X1 mixed / composite · X2 major rebuilt or altered type · X3 underground truss / bridge setup

Platform codes — P1 two side platforms · P2 one island platform · P3 one side platform · P4 bi-level side platforms · P5 bi-level island · P6 loop / terminal

Build eras (color-coded pills) — Early IRT · Dual Contracts · Triboro · BOT (Board of Transportation) · Converted Rail (formerly LIRR / NY Westchester & Boston / etc.) · TA · MTA · MTA Capital

Contract codes (in Route Key) — C1, C2, C3, C4: IRT Contracts · TB: Triboro · IND: Independent Subway System · BRT: Brooklyn Rapid Transit (private builder) · C209 and similar: modern MTA capital contracts

Route numbers in parentheses — e.g. Route 44 (18). The leading number is the City-approved contract route designation; the number in parentheses is the route the line is commonly known by in photographs and unofficial references. The Route Key shows the official number with a "known as" tag beneath it.

ADA badge (green) — Station is ADA accessible.

Closed stations — Dimmed in lists (e.g., City Hall Loop, Worth Street, 18th Street).

Dot (•) next to a station name — Station has additional notes available.

Era pill — Outlined badge indicating the build era of the station.

Terminal tag (gold) next to a station name — the station's terminal operation (Relay, Reverse, Layup…). Full detail on the card.

Every screen has its own web address. As you navigate, the address bar updates — bookmark it or copy it to return to exactly this chain, station, route, yard, or filtered view. The browser back and forward buttons work throughout the app.

The Share button on station cards, yard cards, and the chain and route headers copies the link for the current screen. On mobile it opens your device's share sheet.

Line Key — the first entry in the sidebar returns to the chain index from anywhere in the app.

Search — ⌘K / Ctrl+K opens global search.

Tabs — In Chain mode, switch between Stations, Grades (3.5%+ grades flagged by severity tier, plus the chain's water crossings), Substations and Towers & Relays.

Route Key back link — In a route detail view, tap "← Route Key" at the top of the header to return to the overview.

Mobile — Use the bottom navigation bar to switch between Key, Chain, Route, Crossings, and More (overflow menu for Guide, Glossary, About, and Download Diagram).

Glossary — every term, abbreviation and code used in the database, accessible from the top bar.