The eleven tunnels in order of increasing length:
New Guanjiao Tunnel (32,645 m)
This tunnel, currently China's longest, is along the world-famous Qinghai-Tibet Railway. The relatively low-level, outside-Tibet part of this railway was opened in 1984. 40 years later in 2014, the new tunnel bypassed a section where the old line crossed a mountain range with lots of tight curves and 180-degree loops. It is a state-of-the-art two-tube double-track tunnel.
Map from Contractors World (with typo in the original...)
Koralm Tunnel (32,893 m)
This tunnel is on the new Koralm Railway, which plugs a gap in Austria's railway network between provincial capitals Graz and Klagenfurt. It it is also an element of the thorough upgrade of the connection between north-eastern Italy and Vienna. Although it will certainly bring significant improvements in both domestic and international traffic, the benefits are unlikely to match the costs: this is a political project (pushed through by the late Jörg Haider as governor of Carinthia).
Although the project didn't go ahead as quickly as was expected when I wrote my Tunnels diary a decade ago, now, after the launch of the last tunnel boring machine last October, construction is in full swing, with late 2022 as the completion date.
Gaoligongshan Tunnel (34,531 m)
China has long advocated rail connections to its neighbours in South-Eastern Asia, all of which were held up by politics. The project to connect Myanmar (former Burma), which in particular was seen by the Myanmar opposition as colonialist, only got so far that China is building a line to the border. The line is perpendicular to the many parallel mountain ranges which formed on the edge of the collision of the Indian subcontinent and Asia, requiring extreme tunnelling. Construction started in August 2014, the target date for completion is 2021.
Map of rail lines into South-East Asia advocated by China from Bangkok Post, with location of Gaoligongshan Tunnel added
Lötschberg Base Tunnel (34,576.6 m)
This tunnel is the new centrepiece of Switzerland's secondary trans-Alpine route: the Lötschberg-Simplon line. It was opened in 2007 (see my contemporary diary) in a curious state: for cost-saving reasons, the southern third was double-track, the northern third single-track, and on the middle third, the second tube was bored but no track was laid.
Sketch map from the now defunct LBT official site
By now, the single-track section became a bottleneck (who would have thought?...). At last, planning for the completion of double-track started this year, the go-ahead for construction is expected in 2018.
Yulhyeon Tunnel (50,300 m)
South Korea's successful KTX high-speed network (which I portrayed six years ago) enters Seoul from the south-west, with a terminus in the city's northern half. There are a lot of new housing developments in the southern part of the metropolitan area, however, and the now world-famous upper-class Gangnam district is also in the south-east, so South Korea is building a new branch there: the Suseo High Speed Railway. To save any fuss with locals over noise, almost the entire line is a single tunnel.
With neither hundreds of metres of rock nor dozens of metres of water overhead, geology was a lot less challenging than for the other tunnels in this diary. Construction took just five years. The line is due to open later this year, after the repair of cracks found at one of the stations. Train services will be operated by a new subsidiary of the state railway, creating intra-company semi-competition.
Map from Korea.net
Channel Tunnel (50,450 m)
The Chunnel connects France and the UK since 1994. It is the best-known of the lot, I don't think I have to introduce it to my readers. Over the years I have written in particular about its fire safety.
In the past few years, the Chunnel has been a flashpoint in the immigration "debate": namely, refugees trying to get into the UK by hopping on trains often resulted in traffic closures and material damage. Should Britain now vote for Brexit in the referendum, the situation may get even more messy if France ends its efforts to hold back this stream of migration.
Another recent Chunnel-related news is that the operator of high-speed trains across it, Eurostar, put the first of its new 400 m long e320 trains into operation last November. While Frankfurt–London services are off the table for now, Amsterdam–London is in preparation for next year.
A Eurostar e320 crosses from Belgium into the Netherlands on a test run. Photo by Alex van Herwijnen from Flickr reproduced under CC BY-NC-ND 2.0 (modification: cropping, re-insertion of name)
Seikan Tunnel (53,850 m)
This tunnel connects Japan's main island Honshu with the northern island Hokkaido. It was first conceived after WWII as a weather-proof alternative to ferries (and also safe against floating mines from the Korean War). Two and a half times as long as the longest tunnel at the time, the government only had confidence to launch serious construction in 1971, and even then, it was a bit too much for contemporary technology: there were multiple flooding incidents. Also, the single-tube double-track structure wouldn't meet modern safety standards (now separate single-track tubes for the opposed directions are standard). By the time it was opened in 1988 – almost a decade late –, planes gained overwhelming dominance in passenger traffic, so the tunnel could only gain significance in freight traffic.
The tunnel was planned from the onset to accommodate Shinkansen high-speed trains, which run on standard-gauge tracks and are wider than normal trains in Japan (which are narrow-gauge). However, with the end of Japan's real-estate bubble and the on-set of Western-style budget cutbacks, the expansion of the Shinkansen line to the north was even slower than the completion of the tunnel: the Hokkaido Shinkansen was inaugurated on 26 March 2016 only, running across the Seikan tunnel on dual-gauge tracks at 140 km/h.
An H5 Series Shinkansen exits the Seikan Tunnel. It's well visible in the snow that both tracks are dual-gauge, with three rails. Photo from Figure Miyage
Brenner Base Tunnel (55,600 km)
This trans-Alpine tunnel is to connect Austria and Italy. Due to its connection to the existing Inn Valley Tunnel, which enables freight trains a 64 km travel between tunnel portals, it is marketed as the soon-to-be longest underground railway connection in the world.
Like the Mont d'Ambin Base Tunnel (further down), the BBT project languished in the alibi planning/preparatory works phase for years, but it has slowly entered the proper construction phase and is now slated for opening in 2025. The first sections of the actual main tunnel were bored from 2011 (at the geologically most difficult section, which was crossed without problems by 2015). Unlike the other trans-Alpine tunnels, but similar to the Channel Tunnel, this tunnel will have an exploratory tunnel along its entire length, to reduce geological risks; and to serve later as service tunnel for the two single-track main bores, increasing safety.
Above: 3D drawing (not to scale!) of the Brenner Base Tunnel as seen from the south-west, with the exploratory/service tunnel in yellow; also showing the access tunnels (green), emergency stops (blue), connecting tunnels (purple), as well as the Inn Valley Tunnel on top (light grey), from BBT-SE
Below: May 2016 construction progress diagram from BBT-SE
Gotthard Base Tunnel (57,051 m)
The new longest tunnel in the world is the biggest element of Switzerland's plan to move trans-Alpine freight from roads to rails (see my diary a decade ago). However, that intent has been undermined recently when referendum voters approved a plan to double the Gotthard Road Tunnel. Meanwhile, the plan to extend the GBT to the north (to a length of 75 km) in a second phase, a measure which was chiefly meant to reduce freight train noise in the narrow valleys there, is currently shelved.
Moreover, even though the GBT opened complete (unlike the LBT), its benefits won't be fully realised until 2020, when the shorter Ceneri Base Tunnel opens, tunnels and overbridges along the approaches will be modified for trucks with 4 m corner height, and new semi-high-speed trains will be delivered. The GBT is now also expected to be busier than in the original plans, so the great speed difference between freight and passenger trains is a capacity problem. One solution, coupling pairs of freight trains to form one long train, has now been tested.
Mont d'Ambin Base Tunnel (57.3 km)
This tunnel is very similar to the GBT: a mountain tunnel that is the centrepiece of a semi-high-speed mixed-traffic trans-Alpine line, but in this case between France and Italy (the Lyon–Turin line). The bi-tube tunnel will be constructed from both ends and four access shafts. Uniquely among the 50+ km tunnels, it will have not just emergency stops, but passing loops in the middle (mitigating the capacity limitation due to large speed differences which I noted for the GBT).
3D sketch drawing of the Mount d'Ambin Base Tunnel from LTF-SAS
Construction started once already in 2001, but tendering was soon aborted after a government change in France. The project wasn't killed outright, instead, it was kept alive with alibi activities: geological exploration and preparatory works (boring of access tunnels) was carried out, plans were revised. Meanwhile in Italy, plans of the connecting line to Turin (although mostly tunnel and 200 km/h max) faced significant protests from locals and anti-high-speed-rail campaigners from across Italy – with Beppe Grillo's support – which I viewed as over-the-top NIMBYism (see earlier discussion). One result was a plan change of the base tunnel itself, extending its length by 4 km at the Italian end. Also, preparatory works on the Italian side started in 2012 only (again see ET discussion).
More recently, work started on long exploratory tunnels along the path of the future main tunnel in both Italy and France, in fact the latter will become part of the main tunnel. All in all, paradoxically, what I called "alibi works" created a situation where everything is set for main works to start on short notice and with much better knowledge of the geology than a decade ago. Meanwhile, the governments started to re-commit themselves. The current schedule foresees final parliamentary approval by the end of this year, start of main construction next year, and completion around 2025. I think 2030 is more realistic. That is unless a Five Star Movement government decides to cancel the project.
Bohai Strait Tunnel (123 km)
East of Beijing, two peninsulas from the north and south narrow in the westernmost part of the Yellow Sea. It wasn't a decade ago that a train ferry across the strait was established, but now detailed plans of a world-record tunnel have been drawn up. From an engineering viewpoint, the tunnel is certainly feasible (the straits are very shallow), but I wonder about the economics. It's indisputable that passenger traffic would not justify the at least 200 billion yuan price tag (about the same as the entire Beijing–Shanghai high-speed railway). For freight traffic, however, studies found that bypassing the Beijing area would be a significant advantage for traffic between north-eastern and central and eastern China.
The reason I view this project as the most likely super-long tunnel to be built soon is that it has political support. It was considered for the current Five Year Plan, and although I can't find any reports that it was actually adopted, it may well be in four years, since even the PM backed it. Completion would take eight years.
In contrast, I don't think plans like the c. 40 km Strait of Gibraltar and Pyrenees Central Base Tunnels, the c. 60 km Helsinki to Tallinn and Sakhalin-Hokkaido Tunnels, the 73 km Jeju Undersea Tunnel in Korea, the 90 km Bering Strait Tunnel, the 100 km Irish Sea Tunnel, the 150 km Taiwan Strait Tunnel, the 200 km Japan-Korea Undersea Tunnel, or the 375 km China-Korea Undersea Tunnel have a chance at becoming reality any time soon. Of the above, the tunnel to South Korea's favourite holiday destination, Jeju Island, would be closest to economic viability (Seoul–Jeju is the world's busiest air route), but politics is not too favourable (a second airport on the island has priority).
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