Demodara Loop railway engineering: 360-degree spiral alignment and Tunnel No. 42 clearance?

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Sophie Viaduct910 rep

How did railway surveyors design the 360-degree helical railway spiral at Demodara so trains pass directly beneath the station platform?

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4 Answers from travellers

Accepted Answer

The Demodara Loop on the Main Line extension to Badulla (opened in 1921) is a civil engineering masterwork designed to conquer a sudden 100-foot elevation drop without exceeding the maximum allowable broad-gauge grade (1 in 44). Surveyors looped the track 360 degrees around a natural circular hill spine. Departing Demodara station platform, the track curves sharply along the outer perimeter hill face, passes over the Black Bridge viaduct, and enters Tunnel No. 42 (130 meters long), which burrows directly underneath the Demodara station platform itself. A train rounds the hillside and passes 30 feet below the exact tracks it occupied two minutes prior.

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Eng Jayasinghe SLR1870 rep

Locomotive drivers sound long acoustic horn blasts before entering Tunnel 42 to warn passengers walking across the station platform overhead.

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Sophie Viaduct910 rep

Legend attributes the loop design to a local surveying assistant who suggested modeling the track geometry after the circular folds of a Kandyan head turban.

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Minoli Heritage1850 rep

A dedicated viewing lookout situated on the tea hill path above Demodara station allows photographers to capture the entire loop and tunnel portal in a single frame.

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Sarah Field Scout1720 rep

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