Muzhailing vs Zigana: length, opening date and class compared

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Side by side

Muzhailing is recorded on data/tun10.html and Zigana 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

Muzhailing and Zigana are compared here on the figures this archive records for each, taken from the same sources and the same measurement convention. Driven end to end the two would run 29.7 km, which is the figure to hold against the 24.51 km of the longest single road tunnel in the record.

Muzhailing is the longer of the two at 15.23 km, ahead of Zigana at 14.48 km, a difference of 0.75 km. 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 Muzhailing or Zigana has had.

Both belong to the 2020s, so the two were specified against the same expectations and the length difference is not standing in for a change of era. 18 other structures in this record opened within two years of Muzhailing, which is the cohort it was designed alongside and the fairer comparison for how it was built.

Across every class this archive records, Muzhailing stands 69th by length and Zigana 82nd, so the pair sits inside the top 82 of 244 structures. Counting every class, 12 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.

The 2020s account for 26 entries in this archive, and Zigana 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

That gap is about 5 per cent of the longer bore, which is the figure worth holding on to rather than the raw metres. Only structures open to traffic are compared. 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 road tunnels, so the measurement convention is identical and the comparison is direct. 68 recorded structures are longer than Muzhailing, the nearest of them Firenzuola at 15.29 km. Geology decides cost and programme far more than distance does, so a shorter bore through difficult ground can be the greater achievement.

Muzhailing was designed under the modern regime, with cross-passage spacing and emergency ventilation specified from the outset. Tunnels are regularly repurposed, and the mode a bore was built for is not always the mode it now carries. Trade reporting is faster than official publication and less reliable, which is why opening dates sometimes move after the event.

Among the road tunnels this archive records, Muzhailing stands 10th by length and Zigana 11th, adjacent in the ranking. Pressure waves in a long rail tunnel are severe enough to require relief shafts or sealed carriages. A tunnel outlives the traffic forecast that paid for it, and most of its lifetime cost is ventilation and lighting.

A record only moves when one project completes. A ruling gradient set by the heaviest train decides whether a rail crossing needs a tunnel at all. Gradient limits are the main reason a railway crossing runs longer than a road crossing of the same range. Class conventions differ, so like is compared with like.