Traintrackr

Traintrackr

An MCP server that lets Claude and ChatGPT answer questions about GB (National Rail) trains: *"when's the next train to Sudbury?"*, *"is the 13:00 from Liverpool Street on time?"*, *"how do I get from Cambridge to Sudbury next Saturday morning?"*

The public service runs at traintrackr.live. It is free, and you sign in with an email address; there is no password. The connector address is:

https://traintrackr.live/mcp

Use it

Claude. Traintrackr is listed in Claude's connector directory: open claude.ai/directory/traintrackr, or in claude.ai open Customize → Connectors, choose the + next to Connectors and find *Traintrackr* in the directory. Choose Connect: Claude opens the Traintrackr sign-in page, where you enter your email address and then open the link, or type the six-digit code, in the email it sends. A connector added in claude.ai also works in Claude Desktop and the mobile apps. To add it by address instead, choose Add custom connector, name it *Traintrackr* and paste the connector address.

ChatGPT. ChatGPT adds it through developer mode, on the web, in Plus, Pro, Business, Enterprise and Edu plans; in a workspace, an admin may have to allow developer mode first. Turn on Settings → Security and login → Developer mode, then at chatgpt.com/plugins choose +, name it *Traintrackr*, paste the connector address and choose OAuth. Sign in with your email address as above. In a new chat, choose + → Developer mode and select Traintrackr.

Then ask about trains. traintrackr.live/docs shows what each answer contains, and the limits. The privacy policy and terms of use are on the site too. The server is listed in the MCP Registry as live.traintrackr/traintracker.

The rest of this README describes how the server works and how to run your own copy: locally over stdio for the Claude desktop app, or hosted over HTTP (see Deploy to Render). The timetable is stored in Postgres.

flowchart LR

Claude[Claude] <-->|stdio or HTTP| TT[traintracker]

subgraph Live["Live, next ~2 hours"] D[Darwin Rail Data Marketplace] end subgraph Timetable["Timetable, any future date"] NR[Network Rail SCHEDULE feed] -->|daily download| DB[(Postgres timetable schema)] end TT --> D TT --> DB

Tools

Every tool accepts station names or CRS codes. Ambiguous names ("Sudbury", "Harrow") return the candidates so Claude can ask which one you meant.

Departure board

show_board comes with an MCP App: a client that supports MCP Apps draws its result as a split-flap departure board next to the answer. A client draws the board for every call of a tool that has one, so it is on a tool of its own, which the assistant is told to use only when someone asks to see a board. live_departures and live_arrivals return the same trains and draw nothing. A client without MCP Apps gets show_board's result as it would theirs.

The board is one page, apps/rail/ui/board.html, served as the resource ui://traintracker/board.html. Its style and script are inline and it loads nothing from anywhere. The client hands it the tool's result; it shows up to 12 trains, the station's notices and the data credit. Refresh asks the client to call show_board again with the same arguments, which counts against the rate limit like any other call. The flaps don't turn for someone who has asked their system for reduced motion, and a screen reader gets the trains as a table.

Run your own copy

Everything from here on is for running the server yourself. The public service at traintrackr.live is this code, deployed as described in Deploy to Render.

Try it without accounts (demo mode)

Set TRAINTRACKER_DEMO=1 to test every tool before your accounts are approved. The server then uses generated example data and makes no network requests:

• Timetable: a generated SCHEDULE feed for 25 real stations in East Anglia and London (Liverpool Street, Stratford, Chelmsford, Colchester, Ipswich, Norwich, Marks Tey, Sudbury, Cambridge, Kings Cross and others), running from today for 90 days. Sundays start later. It is stored in its own schema (timetable_demo), apart from the real timetable, and rebuilt each day. Demo mode still needs DATABASE_URL.
• Live boards: Darwin departure, arrival and service-details responses are generated from that timetable in-process. About one train in five runs late, one in 25 is cancelled and one in 12 has a platform change; the same train on the same day always gets the same result. Large stations (Liverpool Street, Kings Cross, Cambridge, …) announce platforms 15 minutes before departure, so the scheduled-platform fallback gets exercised.

Every board and plan carries a note that the data is generated, and data_status reports demo_mode. Ask for stations outside the demo network and you get an empty board.

"env": { "TRAINTRACKER_DEMO": "1" }

Add that to the traintracker entry in the Claude desktop config (see Add to the Claude desktop app), or put TRAINTRACKER_DEMO=1 in .env. Remove it once your keys are in place. Things to try: *"next trains from Liverpool Street"*, *"which platform is the next train from Cambridge to Kings Cross?"*, *"how do I get from Cambridge to Sudbury tomorrow at 9?"*

Accounts you need

1. Rail Data Marketplace (Darwin)

1. Create an account at raildata.org.uk.
2. In the product catalogue, search "Live Departure Board" (the LDBWS product, not "Live *Fastest* Departure Boards") and subscribe. Approval for the free tier ranges from instant to a few days.
3. Open the subscribed product → Specification tab. Copy the Consumer key (not the secret) into DARWIN_API_KEY.
4. Check the base URL on that tab matches DARWIN_DEPARTURES_URL in .env.example. If it differs, set DARWIN_DEPARTURES_URL to your value (everything before /GetDepBoardWithDetails).
5. *(Optional)* Subscribe to Service Details and Live Arrival Board the same way. Each product has its own key and URL: set DARWIN_SERVICE_API_KEY / DARWIN_SERVICE_URL and DARWIN_ARRIVALS_API_KEY / DARWIN_ARRIVALS_URL.

2. Network Rail Open Data (SCHEDULE)

1. Register at the Network Rail data feeds portal. Activation can take a while.
2. Sign in and check that SCHEDULE appears under *Static feeds*.
3. Put your portal username and password in NR_USERNAME and NR_PASSWORD.
4. If the portal gives a different download link for the *full daily extract, all operators, JSON* than NR_SCHEDULE_URL in .env.example, set NR_SCHEDULE_URL to it.

The server downloads the feed in the background when the timetable is missing or older than 26 hours. It checks this on start-up and on every tool call, so a server left running for days stays current. If a download fails it keeps serving the old timetable, and data_status shows the error. You can also run manage.py refresh_timetable --commit by hand (see Commands). Set TIMETABLE_AUTO_REFRESH=0 where a separate job runs refresh_timetable, as on Render.

3. Postgres

The timetable lives in one schema (timetable by default) of the database in DATABASE_URL. The role needs to create schemas in that database; the owner of the database can. On a shared server, give traintracker its own database and role:

CREATE ROLE traintracker LOGIN PASSWORD '…';

CREATE DATABASE traintracker OWNER traintracker; REVOKE CONNECT ON DATABASE traintracker FROM PUBLIC;

Put that role in DATABASE_URL, not the server's own user. The server's user owns every database on it, so a fault in traintracker would reach the other applications' data; the traintracker role reaches its own database only.

The full GB timetable takes about 475 MB (4.3 million stops), and about twice that while a refresh builds the new copy. A refresh takes about 40 seconds plus the download. It builds the new timetable in a staging schema and swaps it in with a rename, so readers never see a half-built timetable, and an advisory lock stops two refreshes running at once.

The tables are UNLOGGED: they are rebuilt from the feed every day, so they skip the write-ahead log and don't add to the server's WAL or point-in-time-recovery storage. The cost is that Postgres empties them after a crash; the tools then report "No timetable yet" until the next refresh.

How each source is used

flowchart TD

Q{What's being asked?} Q -->|next ~2 hours| L[live_departures / live_arrivals]