Chunnel vs Yulhyeon: length, opening date and class compared

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Side by side

Chunnel is recorded on data/rail.html and Yulhyeon on data/rail.html, compiled to the same convention, which is what makes the two figures comparable at all.

How this archive measures: lengths, bores, dates and ordering

How this table is compiled

Chunnel and Yulhyeon are compared here on the figures this archive records for each, taken from the same sources and the same measurement convention. Chunnel belongs to the 1990s and Yulhyeon to the 2010s, two decades in which what a tunnel had to provide by way of escape and ventilation was not the same thing.

Chunnel is the longer of the two at 50.45 km, ahead of Yulhyeon at 50.3 km, a difference of 0.15 km. Driven end to end the two would run 100.75 km, which is the figure to hold against the 57.1 km of the longest single railway tunnel in the record.

That gap is about 0 per cent of the longer bore, which is the figure worth holding on to rather than the raw metres. Both rows are reachable from the railway tunnel table they were taken from, where the note column carries the tube count, the gradient and any reconstruction Chunnel or Yulhyeon has had.

Across every class this archive records, Chunnel stands 3rd by length and Yulhyeon 4th, so the pair sits inside the top 4 of 244 structures. 19 other structures in this record opened within two years of Yulhyeon, which is the cohort it was designed alongside and the fairer comparison for how it was built.

The 1990s account for 28 entries in this archive, and Chunnel is one of them, which is the context a single opening date does not carry on its own. Both pass ten kilometres, which 161 of the 244 structures recorded here manage, so this is a comparison inside a small group rather than across the field.

Reading the figures

Neither holds the record: Gotthard Base at 57.1 km is the longest railway tunnel recorded here, 6.65 km ahead of Chunnel. The fires at Mont Blanc, in the Tauern and in the Gotthard between 1999 and 2001 rewrote European tunnel safety, and every structure opened since reflects that.

Both are recorded in this archive as railway tunnels, so the measurement convention is identical and the comparison is direct. A record for length has changed hands roughly once a decade since the 1870s. A disused rail bore is the commonest cycleway in some countries, which is a second life a length ranking cannot show.

2 recorded structures are longer than Chunnel, the nearest of them Sei-kan at 53.85 km. Tunnels are regularly repurposed, and the mode a bore was built for is not always the mode it now carries. Published lengths for the same structure differ by a few metres between sources, depending on whether cut-and-cover approaches are counted.

Among the railway tunnels this archive records, Chunnel stands 3rd by length and Yulhyeon 4th, adjacent in the ranking. The oldest crossings still carrying traffic were built before any of the codes that now govern their upkeep. Traffic volumes are excluded for the same reason, and because they date far faster than the structures themselves.

Yulhyeon was designed under the modern regime, with cross-passage spacing and emergency ventilation specified from the outset. The loading gauge sizes a railway bore, and a tunnel built for one country's stock can refuse another's. Water under pressure delays a heading more reliably than distance does, and it appears in no ranking.