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Ferritype Architecture

WWTL — RAIL METHODOLOGY
The Ferritype is the structural classification unit for rail infrastructure across the Worldwide Transportation Library. Where a route name or operator tells you what a rail line is called, a Ferritype reduces it to a compact code describing what it physically is — its gauge, its power source, its track layout, and how it's separated from the world around it. This page documents the notation, the reasoning behind it, and real benchmarks drawn from WWTL's own rail archive.
Standard: Ferritype v1 Publisher: WWTL.info Document type: Methodology Companion to: Viatype (road classification, viatology.org)
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The Ferritype String

A Ferritype is assembled from four components read left to right, with an optional fifth appended when needed. Together they describe a rail line's physical infrastructure and operational layout — independent of the railroad's name, owner, or era.

1 Gauge
D Power
the fixed infrastructure
2 Tracks
D Segregation
the operational layout
T Modifier optional
  • Gauge Track Width —the physical width between the rails, fixed at construction. 1 = Standard gauge. 2 = Broad gauge. 3 = Narrow gauge. 4 = Minimum/Industrial gauge. 0 = reserved, unassigned, for non-standard guideway systems (e.g. straddle-beam monorail) not yet represented in the archive.
  • Power Traction Source —C = Catenary (overhead wire). R = 3rd/4th rail. D = Diesel (self-contained). H = Hybrid or transitional power. X = Non-conventional propulsion (maglev, hydrogen — genuine mechanism differences, not running-gear differences).
  • Tracks Track Count —1 = Single track. 2 = Double track. M = Multiple-track trunk (e.g. shared freight/passenger mainlines).
  • Segregation Right-of-Way —D = Dedicated, fully grade-separated, no nearby road crossing. R = Reserved, the train has its own lane but an at-grade road crossing exists nearby. S = Shared-street, running in mixed traffic at grade.
  • Modifier Running Gear —optional, applied only when running gear deviates from conventional steel wheel on steel rail. T = rubber-tired/guided (e.g. Montreal Metro, Mexico City Metro). Omitted entirely for the global default of steel wheels — marking the exception, not the norm.

Gauge and Power are grouped before the dash because they describe the fixed physical/motive infrastructure of a line, set at construction and rarely altered. Tracks and Segregation follow the dash because they describe the operational layout — attributes considerably more prone to change independently of gauge or power, and independent of each other (a line can gain a second track without losing its dedicated right-of-way, or vice versa).

WWTL — Ferritype v1
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International Benchmarks

The Ferritype removes the bias of local terminology — "commuter rail," "S-Bahn," "light rail," "metro" — and exposes the structural reality underneath. These examples are drawn directly from WWTL's own photographic rail archive.

Location System Ferritype Structural Reasoning
San Carlos, California Caltrain 1D-2D Standard gauge, diesel-powered (as photographed in 2007, pre-electrification), double track, grade-separated corridor.
Bay Point, California BART 2R-2D Intentionally broad gauge, 3rd-rail power, double track, fully grade-separated by design.
San José, California VTA Light Rail (Capitol/Tamien) 1C-2D Standard gauge, catenary, double track, physically protected within the Highway 87 median — no at-grade crossings nearby.
Oakdale, California Union Pacific (freight) 1D-1R Standard gauge, diesel, single track, with a named at-grade crossing and signal nearby — reserved right-of-way, not dedicated.
Albuquerque, New Mexico Rail Runner Express 1D-MR Standard gauge, diesel, shared multi-track trunk with BNSF/Amtrak, at-grade street crossing near the platform.
Airolo, Ticino Swiss Rail (Gotthard line) 1C-2D Standard gauge, catenary, double track, grade-separated mainline.
Osaka / Kawasaki, Japan Shinkansen 1C-2D Standard gauge, catenary, double track, fully dedicated high-speed right-of-way.
Montréal, Québec Montreal Metro 1R-2D-T Standard-width guideway, 3rd-rail-equivalent power, double track, grade-separated — plus the Modifier, since it runs on rubber tires rather than steel wheels.
Dublin, Ireland Luas (Red Line) 1C-2S Standard gauge, catenary, double track, running at grade in mixed street traffic — a classic tram.

Ferritypes are assigned to the specific point photographed, not to the line as a whole. A single rail corridor may carry more than one Ferritype along its length — a fenced freight cutting near one town, an at-grade crossing near the next.

WWTL — Ferritype v1
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Era-Authenticity Principle

WWTL's rail photography spans decades, and rail infrastructure changes over that span — corridors get electrified, tracks get doubled, rights-of-way get fenced or opened. Standard engineering practice often documents a line by its current state. Ferritype does not.

A Ferritype code reflects the state of the infrastructure at the time the photograph was taken, not its condition today. Caltrain, for example, carries a diesel-power Ferritype based on 2007 photography, despite the corridor's more recent electrification — because the archive's responsibility is to the historical moment it documents, not to the present-day system.

This mirrors how a documentary photo archive captions its subjects: by what the frame actually shows, not by what has happened since.

WWTL — Ferritype v1
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Field Guide: Reading Segregation

Of the five Ferritype positions, Segregation is the one that most rewards a careful look at the photograph itself. Here's what to look for:

  • Dedicated (D) — no road can reach the tracks at all near this point: elevated viaduct, sunken trench, or continuous fencing with no gaps. If you can't find a nearby spot where a car could cross, it's Dedicated.
  • Reserved (R) — the train has its own lane, but a signed, gated, or lit road crossing exists nearby. Small-town depot stations are frequently this: Main Street crosses the tracks a block or two away.
  • Shared-street (S) — no separation at all. Rails embedded in pavement, train and cars sharing the same surface, as with a classic street tram.

When a photograph is a trackside shot rather than a station (a mile-marker, an arbitrary stretch of line), default to the same Ferritype as the nearest named station on that line, unless something specific in the frame clearly differs.

WWTL — Ferritype v1