Rail catenary pole placement automation

Electrifying a railway line means placing catenary poles one by one along its entire length. The spacing rules are anything but fixed: poles can sit up to about 65 m apart on straight track but tighten to as little as 27 m on sharp curves, with the exact maximum set by curve radius and cant, read from a reference table dozens of pages long.

Then there are the structures. No pole can stand on a tunnel, bridge, viaduct, culvert or overpass, and each structure type carries its own safety buffer, creating a forbidden zone around it.

The firm did this by hand: cross-referencing a spreadsheet, a PDF table dozens of pages long and a structure list, then marking every position on a drawing, kilometre after kilometre. A single line took weeks, small errors were easy to miss, and the whole job started over whenever the line design changed.

I built a Python system that works from the firm's own existing project files, with no new data entry. It isn't tied to one line: track geometry, structures and the spacing table are all read from each project's own files, so a new line means a new configuration file, not new code.

1. It reads the track geometry - straights, curves and transition (clothoid) segments, with radius and cant - directly from the engineering spreadsheet.
2. It turns the maximum-spacing PDF table into structured, cached data using an LLM, removing the manual table lookup entirely.
3. It converts tunnels, bridges, viaducts, culverts and overpasses into forbidden zones with the safety buffer defined for each structure type, merging any that overlap.
4. It walks the line from start to finish and places every pole according to the defined rules: tightening spacing through curves, skipping tunnels, and adding a pole just before the entrance and just after the exit.
5. It converts kilometre positions into real UTM coordinates - using Fresnel integrals through the transition curves - and outputs an Excel file for review plus DXF/DWG that open directly in AutoCAD.

The process itself changed. What an engineer used to lay out by hand over weeks is now placed automatically against the defined rules, drawn straight into an AutoCAD file, and delivered ready to use.

Correctness was proven, not assumed. The output was compared pole for pole against 4,351 coordinates the firm's own engineers had placed by hand on a 148 km reference line, backed by 68 automated tests covering geometry, structure handling, coordinate conversion, placement logic and output format.

Stack: Python, a greedy placement algorithm, LLM-assisted PDF parsing, UTM coordinate transformation, and Excel/DXF/DWG output.