All in metres
Coach length, bogie offset, curve radius, number of tracks, gauge (1.435 m standard) and clearance.
Desktop app · Python · Streamlit
What a coach does on a curve
A small Streamlit app that shows what happens when a railway coach goes round a curve. Set the coach length, the distance between its bogies, the curve radius, the gauge, the number of tracks and a safety clearance.
It computes the centre throw (how far the middle of the coach cuts inside the curve) and the end throw (how far its corners swing outside), and draws the coaches from above so you can see whether adjacent tracks keep their clearance.
What it does
Centre throw
From the versine of the bogie chord.
End throw
The corner overhang beyond the bogies.
Drawn from above
Tracks and coaches with the clearance envelope (matplotlib).
Explore
Random and reset buttons try other configurations quickly.
Run it
uv installs Python 3.12 and the dependencies (Streamlit, matplotlib, NumPy). Run it from the project folder, so Streamlit reads its settings; it opens at http://localhost:8501.
uv sync
uv run streamlit run src/railway_geometry_visualiser/main.pyPrivacy
It runs locally: the project's Streamlit settings bind it to localhost (Streamlit's default listens on your whole network and looks up your public IP) and turn off Streamlit's usage statistics. It stores nothing; inputs live in the browser session.
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