Gotthard Base vs Sei-kan: length, opening date and class compared

• 5entries listed

Side by side

Gotthard Base is recorded on data/rail.html and Sei-kan 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

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 Gotthard Base or Sei-kan has had. Spoil from a long bore is a civil work of its own, and outside several alpine portals it has become a permanent landform.

That gap is about 6 per cent of the longer bore, which is the figure worth holding on to rather than the raw metres. 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.

At over twenty kilometres Gotthard Base sits in the small group of bores long enough to need intermediate ventilation and a full escape regime. Driven end to end the two would run 110.95 km, which is the figure to hold against the 57.1 km of the longest single railway tunnel in the record.

Gotthard Base and Sei-kan are compared here on the figures this archive records for each, taken from the same sources and the same measurement convention. 19 other structures in this record opened within two years of Gotthard Base, which is the cohort it was designed alongside and the fairer comparison for how it was built.

Across every class this archive records, Gotthard Base stands 1st by length and Sei-kan 2nd, so the pair sits inside the top 2 of 244 structures. The 1980s account for 25 entries in this archive, and Sei-kan is one of them, which is the context a single opening date does not carry on its own.

Reading the figures

Gotthard Base is the longer of the two at 57.1 km, ahead of Sei-kan at 53.85 km, a difference of 3.25 km. 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.

Gotthard Base is the longest railway tunnel in this archive, which makes this comparison one against the record itself rather than two entries below it. The note column carries the qualifications. A crossing driven from both ends meets in the middle, and the survey needed to make that happen is invisible in the finished figure.

Both are recorded in this archive as railway tunnels, so the measurement convention is identical and the comparison is direct. Among the railway tunnels this archive records, Gotthard Base stands 1st by length and Sei-kan 2nd, adjacent in the ranking. Ventilation arrangement caps how long a bore can be driven more directly than money does.

Gotthard Base was designed under the modern regime, with cross-passage spacing and emergency ventilation specified from the outset. Structures still under construction cannot hold a record here, and are listed separately until they carry traffic. A boring machine has to be assembled underground and is economic only past a length that varies with the rock.

0 recorded structures are longer than Gotthard Base — nothing in this archive is. Both figures come from the same archive and the same convention. Portal design follows avalanche and rockfall exposure rather than architectural intent. Pressure waves in a long rail tunnel are severe enough to require relief shafts or sealed carriages.