{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.spiral-q846907","code":"thing-q846907","url":"https://ver.cy/models/thing/q846907/","name":"spiral","alternateNames":[],"kind":"thing","status":"published","version":"0.2.0-wave.4","language":"en","classifiers":{"family":"Thing Registry","category":"Physical world and living systems","entryKind":"thing","plane":"PHY","domain":["PHY.BLT"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"In the sense of a fixed construction, a spiral or spiral loop is a route alignment, most often on railways, in which the line curves through a full circle and crosses over or under itself, often via a viaduct or tunnel, to gain height within a short distance on steep terrain, as on the Brusio spiral viaduct on the Bernina line, the spiral tunnels of the Gotthard railway and the Tehachapi Loop in California; road spirals and spiral ramps use the same principle. The geometric curve called a spiral is a separate concept.","purpose":"Let an agent explain spiral loops in transport engineering, relay design principles and notable examples from railway and civil engineering sources, and distinguish spirals from switchbacks or zigzags, horseshoe curves, helical ramps in buildings and the mathematical spiral curve.","scope":{"in":[],"out":[],"boundaries":[]},"distinguishingFeatures":["Crosses itself","Gains height compactly","Keeps gradients manageable","Often uses tunnels or viaducts"],"structure":{"bundles":[{"id":"understand","name":"Understand","description":"What a spiral loop is.","layers":[{"id":"definition","name":"Definition","description":"Definition.","findings":[{"id":"definition-finding","name":"Definition","description":"Definition.","questions":[{"text":"What is a spiral in route engineering, and how does it differ from switchbacks, horseshoe curves, helical ramps and the geometric spiral?","kind":"definition"},{"text":"Is the question about railways, roads, a specific loop or mathematics?","kind":"boundary"}]}]},{"id":"examples","name":"Examples","description":"Examples.","findings":[{"id":"examples-finding","name":"Examples","description":"Examples.","questions":[{"text":"What are the Brusio spiral viaduct, the Gotthard spiral tunnels and the Tehachapi Loop?","kind":"definition"},{"text":"Which entry fits the specific spiral?","kind":"action"}]}]}]},{"id":"engineering","name":"Engineering","description":"Engineering.","layers":[{"id":"gradient","name":"Gradient","description":"Gradients.","findings":[{"id":"gradient-finding","name":"Gradient","description":"Gradient.","questions":[{"text":"Why do railways need spirals to keep gradients manageable?","kind":"provenance"},{"text":"Which references are standard?","kind":"provenance"}]}]},{"id":"construction","name":"Construction","description":"Construction.","findings":[{"id":"construction-finding","name":"Construction","description":"Construction.","questions":[{"text":"How are spiral tunnels and viaducts built?","kind":"provenance"},{"text":"Which sources are cited?","kind":"provenance"}]}]}]},{"id":"operations","name":"Operations","description":"Operations.","layers":[{"id":"trains","name":"Trains","description":"Train operations.","findings":[{"id":"trains-finding","name":"Trains","description":"Trains.","questions":[{"text":"How do curves in spirals limit train length and speed?","kind":"provenance"},{"text":"Which entry fits minimum railway curve radius?","kind":"action"}]}]},{"id":"roads","name":"Roads","description":"Road spirals.","findings":[{"id":"roads-finding","name":"Roads","description":"Roads.","questions":[{"text":"Where are spiral roads and bridges used?","kind":"provenance"},{"text":"Which entry fits hairpin turn?","kind":"action"}]}]}]},{"id":"context","name":"Context","description":"Heritage.","layers":[{"id":"heritage","name":"Heritage","description":"Heritage.","findings":[{"id":"heritage-finding","name":"Heritage","description":"Heritage.","questions":[{"text":"Which railway spirals are protected heritage?","kind":"provenance"},{"text":"Which entry fits Rhaetian Railway in the Albula and Bernina Landscapes?","kind":"action"}]}]},{"id":"geometry","name":"Geometry","description":"Geometric spiral.","findings":[{"id":"geometry-finding","name":"Geometry","description":"Geometry.","questions":[{"text":"How does the mathematical spiral differ from a helix and a spiral loop?","kind":"provenance"},{"text":"Which entry fits helix?","kind":"action"}]}]}]}]},"agentConduct":{"may":["Explain spiral loops on railways and roads as a way to gain height in a short distance, with examples from railway history.","Describe the engineering reasons for a spiral alignment, such as limiting gradients.","Distinguish a spiral loop from a spiral curve, a spiral staircase or the mathematical spiral."],"mustNot":["Encourage people to walk on the tracks or tunnels of a spiral loop to photograph trains.","Interfere with signalling or train operations on a spiral line.","Present amateur estimates of gradients or radii as engineering data for design.","Give track access information that would let someone enter restricted railway areas."],"requiresHuman":["Changing the operation or speed limits on a spiral section of an active railway."]},"ethics":{"considerations":["Spiral loops often run through remote tunnels where trespass is especially dangerous.","Historic spirals are engineering heritage worth protecting."],"affectedParties":["Railway staff","Passengers","Trespassers and rail enthusiasts"]},"owners":{"steward":"The railway or road infrastructure manager responsible for the line.","roles":[],"masterSystems":[]},"relations":[{"target":"Q811430","type":"parent","note":"registry parent class"},{"target":"fixed construction","type":"related","note":"in registry terms"},{"target":"mountain railway","type":"related"},{"target":"Brusio spiral viaduct","type":"related"},{"target":"zig zag railway","type":"related"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.spiral-q846907","Wikidata: Q846907 (https://www.wikidata.org/wiki/Q846907)"]},"properties":{"applicability":"required","items":["Brusio spiral viaduct: 1908 year - Bernina Railway, UNESCO site","Tehachapi Loop: 1876 year - California","Gotthard spiral tunnels: 1882 year - line opening"]},"recognition":{"applicability":"required","items":["Looping route alignment that crosses itself to gain height","Spiral loop, spiral tunnel, spiral viaduct, Tehachapi Loop","Switchbacks reverse direction; horseshoe curves do not cross themselves; the mathematical spiral is a curve","A track or road looping in a circle and passing over or under itself."]},"capabilities":{"applicability":"required","items":["explain design principles","relay notable examples","describe variants","distinguish related alignments"]},"hazards":{"applicability":"required","items":["Confusing the engineering and geometric senses","Tight curves limiting train length and speed","Ambiguous registry sense of spiral"]},"interfaces":{"applicability":"required","items":["Railway gradient and curvature standards","Heritage listings for historic spirals"]},"context":{"applicability":"required","items":["Gaining elevation on steep routes.","spiral viaducts","spiral tunnels","surface loops","road spirals","helical ramps"]}},"sources":[{"title":"Wikidata item Q846907: spiral","url":"https://www.wikidata.org/wiki/Q846907","note":"identity and sense of the item"},{"title":"Wikipedia: Spiral (railway)","url":"https://en.wikipedia.org/wiki/Spiral_%28railway%29","note":"general description of the item"}],"openQuestions":["Should the registry sense of spiral be confirmed as the railway loop?","How should railway engineering sources be linked?","Should spiral tunnels be a separate entry?"],"resources":{"spec":"/models/things/publications/thing-q846907/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q846907/spec.json"],"providers":["Claude"],"researchStatus":"unreviewed","generatedAt":"2026-09-13T19:45:18Z","builder":"tools/build_cards.py@1.0.0"},"completeness":{"sections":{"classifiers":"filled","whatItIs":"filled","purpose":"filled","distinguishingFeatures":"filled","structure":"filled","agentConduct":"filled","ethics":"filled","owners":"filled","relations":"filled","interaction.identity":"filled","interaction.properties":"filled","interaction.recognition":"filled","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"filled","interaction.context":"filled","sources":"filled"},"notes":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-06T19:52:02+00:00: completeness 1.00; sense: Wikidata description; 2 live sources; review by codex: pass"},"score":1.0}}