Koralm vs New Guanjiao: length, opening date and class compared

• 5entries listed

Side by side

Koralm is recorded on data/rail.html and New Guanjiao 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

At over twenty kilometres Koralm sits in the small group of bores long enough to need intermediate ventilation and a full escape regime. 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 Koralm or New Guanjiao has had.

Neither holds the record: Gotthard Base at 57.1 km is the longest railway tunnel recorded here, 24.2 km ahead of Koralm. This archive separates 4 classes of structure and both entries here are indexed under railway tunnel, which decides the table each is ranked in and the convention its length was measured by.

That gap is about 1 per cent of the longer bore, which is the figure worth holding on to rather than the raw metres. Driven end to end the two would run 65.55 km, which is the figure to hold against the 57.1 km of the longest single railway tunnel in the record.

Koralm and New Guanjiao are compared here on the figures this archive records for each, taken from the same sources and the same measurement convention. The 2010s account for 69 entries in this archive, and New Guanjiao is one of them, which is the context a single opening date does not carry on its own.

Across every class this archive records, Koralm stands 9th by length and New Guanjiao 10th, so the pair sits inside the top 10 of 244 structures. 16 other structures in this record opened within two years of Koralm, which is the cohort it was designed alongside and the fairer comparison for how it was built.

Reading the figures

Koralm is the longer of the two at 32.9 km, ahead of New Guanjiao at 32.65 km, a difference of 0.26 km. Comparing two tunnels on length alone is the question most readers ask and the least informative answer available, which is why the differences that matter are set out below.

Both are recorded in this archive as railway tunnels, so the measurement convention is identical and the comparison is direct. 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. Both structures link to their own class table.

Among the railway tunnels this archive records, Koralm stands 9th by length and New Guanjiao 10th, adjacent in the ranking. 8 recorded structures are longer than Koralm, the nearest of them Lötschberg at 34.58 km. Adding a metre to the longest tunnel in the world costs what adding a kilometre to an ordinary one does.

Koralm was designed under the modern regime, with cross-passage spacing and emergency ventilation specified from the outset. A base tunnel trades much greater length for a far lower summit altitude, which changes what the number means. Gradient limits are the main reason a railway crossing runs longer than a road crossing of the same range.

A ruling gradient set by the heaviest train decides whether a rail crossing needs a tunnel at all. Class conventions differ, so like is compared with like. Nothing on this page requires scripting to read. Depth below sea level is recorded where published. Figures are checked against one another where they differ.