Tianshan Shengli vs Laerdal: length, opening date and class compared

• 5entries listed

Side by side

Tianshan Shengli is recorded on data/tun10.html and Laerdal on data/tun10.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 Laerdal sits in the small group of bores long enough to need intermediate ventilation and a full escape regime. Both rows are reachable from the road tunnel table they were taken from, where the note column carries the tube count, the gradient and any reconstruction Tianshan Shengli or Laerdal has had.

That gap is about 10 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 road tunnel, which decides the table each is ranked in and the convention its length was measured by.

Laerdal is the longest road tunnel in this archive, which makes this comparison one against the record itself rather than two entries below it. Driven end to end the two would run 46.64 km, which is the figure to hold against the 24.51 km of the longest single road tunnel in the record.

Tianshan Shengli and Laerdal are compared here on the figures this archive records for each, taken from the same sources and the same measurement convention. 16 other structures in this record opened within two years of Tianshan Shengli, which is the cohort it was designed alongside and the fairer comparison for how it was built.

Across every class this archive records, Laerdal stands 20th by length and Tianshan Shengli 28th, so the pair sits inside the top 28 of 244 structures. Counting every class, 7 recorded structures fall between these two by length; the comparison is a window on that part of the record rather than a gap in it.

Reading the figures

Laerdal is the longer of the two at 24.51 km, ahead of Tianshan Shengli at 22.13 km, a difference of 2.38 km. The 2000s account for 53 entries in this archive, and Laerdal is one of them, which is the context a single opening date does not carry on its own.

Both are recorded in this archive as road 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. Opening year means the year traffic was admitted.

Among the road tunnels this archive records, Tianshan Shengli stands 2nd by length and Laerdal 1st, adjacent in the ranking. The most useful sources are the least accessible: inspection records and commissioning documents rather than announcements. A hard shoulder inside a tunnel is expensive width, which is why a breakdown there is treated as an emergency.

Tianshan Shengli was designed under the modern regime, with cross-passage spacing and emergency ventilation specified from the outset. 19 recorded structures are longer than Laerdal, the nearest of them Pajares Base at 24.6 km. Cross-border schemes require two states to fund the same hole at the same time, which is why they take decades.

Round figures in an old record are usually estimates that hardened into fact. Class conventions differ, so like is compared with like. Both structures link to their own class table. Widening an existing bore is rarely economic, so capacity is added by driving a second one alongside. Depth below sea level is recorded where published.