Lots of long tunnels

The first tunnel longer than 10 km, Fréjus on the Franco-Italian border, opened 1871. 35 years later, the Simplon tunnel pushed the record to just under 20 km – but kept it for 76 years, when a Japanese tunnel only some 2 km longer took over.

But after twice six years, two 50+km tunnels led the list. after a further 25 years, there'll be five super-long 50+km tunnels (all three new across the Alps, one of them relieving the old Fréjus tunnel), and then a continuum from 35 km down, with Simplon relegated to only about 20th place! So what enabled this? Three factors:

• Electric traction: now the standard on European and East Asian mainlines, it eliminates the problem of ventilating out noxious gases.
• No space: the demand side is that cities want building space & no traffic barriers, inhabitants want no noise, and there is no place for further lines in mountains.
• Mechanisation: While tunnel boring is still dangerous business, it is now done with highly efficient vehicle-mounted mechanized drillers or tunnel boring machines (TBMs), and geologic prediction developed a lot too.

The first point, plus domination among TBM manufacturers, plus heavy state investment into public transport (especially high-speed rail), explains why the list below is exclusively European/Far Asian. In Europe, beyond the Alps, Spain and Italy are very prolific tunnel-diggers.

Tunnel chains

The Joetsu Shinkansen, opened 1982, cuts right through the central mountains of Japan to the western shore – 102 km of tunnels on a 130 km section! This is what I mean by subwayisation. The European champion in this is Italy – for example, over 90% of the new 78 km Bologna–Florence high-speed link (opens 2007) is in seven tunnels (map), the last of which was broken through six weeks ago.

Rio dei Cani crossing between Sadurano and Monte Bibele tunnels south of Bologna, Bologna–Florence high-speed line (screen capture from promo video [WMV!])

But all three main links across the Alps will be tunnel chains, too: those giant 50+km base tunnels will be less than half the corresponding line's in-tunnel total. For example, the Franco-Italian Lyon–Turin link will have seven more long tunnels, adding up to c. 80 km.

Tunnel complexes

We'd imagine tunnels as a tube across a rock. But nowadays, they build systems of tubes and shafts. For a start: for safety reasons, the emerging new norm is to separate traffic directions in twin tunnels: no danger of frontal collision, and one tube can be the other's escape tunnel. Super-long tunnels also have emergency stations – ventilation and evacuation routes make these a whole world under the Earth:

Current state of progress on the Sedrun access/emergency station complex on the Gotthard Base Tunnel (screenshot of end of Flash movie here). The emergency station, with a ski resort 800 m above it, may be converted to passenger station Porta Alpina

But what makes some newer tunnels really complex is interconnections. For example, the Innsbruck bypass tunnel in Austria was built so that it connects to the Brenner pass route, but also has branching-off tunnel stubs for future underground connection to the Brenner Base tunnel, and another towards a future western portal!...

(If your head is not spinning, check out a longer piece I wrote on tunnels on my own blog earlier this year.)

List of 20+km tunnels¹
(excluding subway, water, sewage and pipeline tunnels)

1. Gotthard Base 57,051 m (75 km with later extension)
   Switzerland. 54.1% of all shafts and tunnels bored, to be opened around 2015
2. Brenner Base 55,600 m (64.3 km with exit across Innsbruck bypass tunnel)
   Austria/Italy. Detailed geological research begins this year, I don't think target date of 2015 can be made
3. Seikan 53,850 m
   Japan, Honshu–Hokkaido subsea tunnel, to be made part of Tohoku/Hokkaido Shinkansen (from Tokyo to the north) with rails relaid, world's longest since opening 1988
4. Mount d'Ambin Base 53,100 m
   France/Italy, main part of Lyon–Turin link. Access shaft constructions underway, also NIMBY protests at Italian end. Opens after 2015
5. Channel Tunnel (Chunnel) 50,450 m
   Famous Franco-British subsea tunnel and (in no small part thanks to Thatcher) financial wreckage, opened 1994
6. Lötschberg Base 34,577 m
   Switzerland, Simplon line, breakthroughs 28 April this year, opening (as world's 3rd longest) with second tube half-finished in 2007
   
7. Koralm 32,800 m
   Austria, south-west of Graz, central part of long-missing but way-too-expensive mainline to Klagenfurt (Jörg Haider lobbied for it), detailed geologic investigations/access tunnels started this year, to be opened 2016
8. Semmering Base 29,000 m
   Austria, south-west of Vienna, long-running squabbles may yet hold up start of construction and opening planned at the same time as the Koralm Tunnel (see my very first Monday Train Blogging)
9. Guadarrama 28,419 m
   Spain, north of Madrid, breakthroughs 5 May/1 June this year, on new Madrid–Segovia–Valladolid high-speed line to be opened 2007 (making Guadarrama world's then 4th longest)
10. (Taihang Shan?) 27,800 m
    China, south-east of Beijing, on new Shijiazhuang–Taiyuan high-speed line to be opened for 200 km/h for the 2008 Olympics already – I believe when I see it, construction started only this year
11. Hakkoda 26,455 m
    Japan, Tohoku Shinkansen, breakthrough in February this year, on section Hachinohe–Aomori to be opened 2010
12. Iwate–ichinohe 25,810 m
    Japan, Tohoku Shinkansen, on Morioka-Hachinohe section opened 2002 (making the tunnel world's 3rd longest)
13. (Wonju–Jecheon) 25,100 m
    South Korea, east of Seoul between said cities, I don't know much beyond that the plan has been accepted last year
14. Pajares 24,667 m
    Spain, high-speed line to Oviedo/Gijón. Three of five main bores began this year, remaining two soon, opens about 2010

• Laerdal 24,510 m
  Norway – world champion of road tunnel construction with its fjords –, road to Bergen. By far the longest road tunnel, opened 2000. Single-tube: the clock is ticking for a fire disaster

15. Wienerwald+Lainzer 23,940 m
    Austria, two-section tunnel connecting the new high-speed line from the west into two terminals in Vienna. Wienerwald main bores started this year, Lainzer earlier, opens 2012 (Lainzer part possibly only later)
16. Iiyama 22,225 m
    Japan, on the extension of the Hokuriku Shinkansen (which was built for the Nagano Winter Olympics). Digging well advanced, but line opens only in 2013
17. Daishimizu 22,221 m
    The third tunnel built under a demanding mountain pass north-west of Tokyo, on the Joetsu Shinkansen opened in 1982 (making Daishimizu then world's longest)

1. There is no official institution in the world keeping track of tunnels – but Gunnar Lotsberg of Norway does that on his site (to which I am a contributor), which has good enough reference value for even UN documents having had plagiarised it. But I'd owe him some updates, which are in the list here.↑

Previous Monday Train Bloggings:

1. (Premiere/ modern Austrian trains & locos)
2. Adventure
3. Fast Steam
4. Heavy Haul
5. Forgotten Colorado
6. The Hardest Job
7. Blowback
8. Highest Speed
9. New England Autumn
10. Trainwreck
11. Bigger Than Big Boy