Mizuho Channel Tunnel
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 The entrance to the Mizuho Channel Tunnel, as seen from the UK entrance | |
| Overview | |
|---|---|
| Location | Lucian Channel (Strait of Shana) |
| Status | Active |
| Route | Kurosu Channel Expressway Chiyoko Route |
| Start | Hampden, Lucis, United Kingdom |
| End | Ibara, Toyone, Kirisaki |
| Operation | |
| Opened |
|
| Operator | |
| Traffic | Automobile Train |
| Technical | |
| Track length | 44.5 km (27.65 mi) (38.7 km (24.05 mi) undersea) |
| No. of tracks | 1 double track rail tunnel 1 service tunnel |
| No. of lanes | 4 |
| Track gauge | Dual gauge |
| Electrified | 25 kV AC OHLE, 50 Hz |
| Operating speed |
|
The Mizuho Channel Tunnel, also known as the Shana Tunnel (Miranian: 夏奈トネル, Shana Tonneru; alternatively 夏奈隧道, Shana Zuidō) is a 44.5-kilometre rail and road tunnel, connecting the city of Hampden, United Kingdom, to Ibara, Toyone, in northern Kirisaki.
The Mizuho Channel Tunnel is one of the longest tunnels in Tyran, and it also holds the distinction of being the longest tunnel in the region with an undersea segment. It primarily serves as a bridge between the road and rail systems of both the United Kingdom and Kirisaki, linking the Kurosu Channel Expressway and the Chiyoko Route. The United Kingdom's primary rail operator, Royal Lucis Railways, operates the Brighton Line through the tunnel, where it merges with the Asahinoda Line operated by Imperial Rail.
First granted planning permission in 1965, construction of the tunnel proper did not begin until 1983 due to difficulties in securing funding for the project. The Mizuho Channel Tunnel was completed in early 1995, and was duly opened on June 25, 1995, with rail services linking both countries via the tunnel commencing two months thereafter.
History
Interest in the construction of a fixed link between the Lucis mainland and Kirisaki has been longstanding, stretching back as far as the early 1810s, when the economist Akaza Yukawa, in collaboration with Inari Imagawa, produced detailed proposals for a tunnel spanning the Strait of Shana. Yukawa and Imagawa's architectural design was fairly rudimentary by modern standards, calling for an excavated, two-tiered tunnel illuminated by gas; however, the tunnel design incorporated plans for a vast, accompanying underground township, with paved roads intended to accommodate both pedestrians and horse-drawn coaches. While garnering plenty of interest from academic circles due to the unique nature of the proposal, it was ultimately unable to gain much support within the corridors of power in Kirisaki, in part due to Yukawa and Imagawa's failure to assuage concerns that such an ambitious construction project would not be economically or technologically feasible.
In 1878, the Imperial government under Shōnan explored the idea of constructing a rudimentary railway tunnel beneath the Strait, linking the Lucis mainland and Kirisaki at Hampden and Ibara respectively. Extensive geological and hydrographical surveys were commissioned; the results of which were used to draw up detailed plans for such a tunnel. The head of the Imperial Engineer Corps, Minami Nikaho, together with the Sentinel of Infrastructure and Public Works, Aoi Kishida, submitted initial proposals to the Grand Council. Exploratory work on the Kirisakian side of the tunnel commenced in 1882, but failure to agree funding schemes for the project with the United Kingdom caused the project to be abandoned in 1885, with barely 5 kilometres of tunnel constructed.
In the late 1950s, ideas for what would eventually become the modern Mizuho Channel Tunnel began to surface once again. The United Kingdom, by this time profiting from a burgeoning trading relationship with Kirisaki, recognised the need for a more expedient method to transport freight from Kirisakian factories to Lucian ports. Similarly, Kirisakian manufacturers, painfully aware of rising shipping costs arising from the rapid unionisation of Kirisakian labour as well as severe congestion in Kirisakian ports, lobbied strongly for a cheaper alternative link to mainland Lucis. Viability studies jointly commissioned by the Lucian Ministry of Transport and Aviation and the Sentinelry of Economy and Trade showed that were the two countries to be connected via a fixed link, the average cost of transporting freight would plummet by over 30 per cent, while also significantly decreasing the amount of time required for the transport of the same.
In 1957, the Lucian Minister of Transport and Civil Aviation, Jun Ogino, together with the President of the Board of Trade, Peter Watkinson, unveiled initial proposals for the construction of a new roadway bridge connecting Lucis and Kirisaki. The entire structure, which was envisioned to be 38 kilometres long, would be a self-anchored suspension bridge constructed primarily from steel and concrete. However, the idea was not at all well-received; Kirisakian authorities, none of which had been consulted over the design of the bridge, dismissed it over fears that such a bridge would block shipping travelling through the Strait of Shana, whereas members of the parliament of the United Kingdom, concerned that the cost of constructing and maintaining a self-anchored suspension bridge over such a large body of water would be prohibitive, failed to approve the proposal.
The need for a fixed link between the United Kingdom and Kirisaki remained pressing, however, leading to the Sentinel of Infrastructure and Public Works at the time, Jun'ichi Morishima, issuing an invitation to Ogino to attend talks concerning the design of such a link. The Special Committee for a Lucian-Kirisakian Fixed Link was subsequently formed in 1966, tasked with investigating various fixed link designs in order to determine the most suitable for use between the United Kingdom and Kirisaki. In 1968, after two years of discussions, members of the special committee reached consensus, deciding that the construction of an undersea tunnel of the immersed tube variety would be economically viable. Immediately following Imperial assent by the tenshi Erii, the Imperial Committee on Infrastructure asked for, and received, a series of comprehensive reports from the special committee, which also detailed the major factors in favour of a fixed link -
- To promote local economic development in the vicinity of the link;
- To improve transport links and encourage tourism between both countries;
- To reduce the amount of marine traffic in the Lucian Channel/Straits of Shana;
- To mitigate the environmental impact of shipping on the Lucian Channel/Straits of Shana;
- To increase bilateral trade volume, improve and further evolve the trading relationship between both countries; and
- To mitigate rising shipping costs, allowing domestic manufacturers to be more competitive in each others' markets.
Following Erii's assent to the project, the Imperial Diet soon followed suit, passing a budgetary bill allocating funds for the construction of the proposed tunnel in the summer of 1970. Once Lucian approval of the project proposal had been successfully obtained, the necessary geographical, hydrographical and seismological studies were commissioned. Although the proposal had gained much traction in the public imagination, as compared to a decade ago, various technical difficulties, including the surprising discovery of minor, but not insignificant, deposits of rare-earth metals beneath the proposed route, meant that exploratory work on the tunnel had to be delayed repeatedly.
A further complication was the publishing of a second costing report commissioned by the politically independent Imperial Office of Budgetary Oversight in late 1972, showing that Kirisakian costs for the project was likely to cost in excess of 548 billion rin, 150 billion rin more than what had previously been allocated. The Radiant Future government of Haruka Sakurauchi, while supportive of injecting fresh funds into the project, saw their efforts to pass a new appropriations bill in the Imperial Diet stymied by a combination of united conservative opposition and erupting backbench rebellions against a project increasingly seen as a white elephant. Further attempts by successive Radiant Future governments to resurrect the project were similarly futile; it was not until 1983, when Satoshi Miyano's coalition government managed to secure much-needed funding from the private sector, in return for export incentives for Kirisakian goods shipped to the United Kingdom as well as time-limited concessions on rail operation, that large-scale construction work finally began in earnest.
A consortium comprising the Lucian corporations Hoerzen and Matsuharu Heavy Industries, together with the Kirisakian conglomerate Sphere and the Lirinyii Frostfire Group, was awarded the tender for the tunnel project on 25 May 1983, and construction work began roughly six months later. Construction proceeded without much issue for the most part, aside from several minor industrial accidents - none of which resulted in severe injury to members of the workforce - and work on the tunnel was completed sometime in March 1995. It was duly opened to traffic roughly two months later, on June 25, and rail services through the tunnel, jointly operated by Royal Lucis Railways and Northern Light Railways, commenced on August 27, 1995.
Structure and construction
The Mizuho Channel Tunnel is an immersed tube tunnel. Measuring a total of 44.5 kilometres in its entirety, the tunnel's cross section is trapezoidal, with a maximum total width of 38.8 metres, and a uniform height of 10.2 metres. The tunnel reaches a maximum depth of 8.6 metres below the seabed and 220 metres below sea level. The tunnel itself is divided into five separate sections, with two sections carrying rail tracks, a further two carrying double-lane roads, and the fifth, a ventilation shaft, also serving as an escape route in the event of emergencies.
There are two undersea stations located within the tunnel - Winona Higurashi station on the Lucian side and Oumi-Kaitei station on the Kirisakian side. These stations were built as emergency escape points, providing the equivalent safety of a shorter tunnel. Various safety features, including exhaust fans, sprinkler systems, thermal sensors, emergency lighting and coupled fire alarm systems were installed at these stations in order to provide for enhanced evacuation effectiveness in the event of an emergency.
The tunnel has dual gauge capability, providing service for trains employing either narrow or standard track gauges. Originally, the track laid down through the tunnel was 1,067 mm (3 ft 6 in) (narrow gauge), chosen primarily for its lower cost, but 1,435 mm (4 ft 8½ in) standard gauge track was installed five years after the tunnel's completion in order to accommodate for increasing rail traffic partially brought about by the increasing adoption of high-speed passenger trains using standard track gauges within Kirisaki.
Separate prefabricated segments of the tunnel, constructed in Lucian and Kirisakian drydocks, were towed to the construction site and sunk in place with the addition of extra weight, aligning with a trench dug to provide support for the construction elements. The segments were then emptied of water and made watertight, and this process continued sequentially along the entire route of the tunnel. In total, 408 distinct reinforced concrete segments were used in the construction of the Mizuho Channel Tunnel. Sections of the tunnel that were above sea level, connecting to the undersea sections, were constructed with the use of slurry shield tunnel boring machines - necessary due to the granular nature of the ground, precluding the usage of other TBMs.
Operation
The rail link through the Mizuho Channel Tunnel is jointly operated by Royal Lucis Railways in the UK and the Kirisakian national railway corporation, Imperial Rail. Connected to the Brighton Line in the United Kingdom and the Asahinoda Line on the Kirisakian side of the tunnel, the rail link serves both high-speed passenger trains and freight trains travelling between both countries.
Regular train services through the tunnel are operated by both the Royal Lucis Railways and Imperial Rail; the RLR operates a series of new dual-voltage trains through the tunnel to Aonomori station in Ibara, while Imperial Rail's high-speed passenger train network ferries its users to North Hampden Station in the United Kingdom, where it connects with the UK's Brighton Line. The RLR typically operates one train through the tunnel every twenty minutes, with the frequency alternating from one train per hour during non-peak hours to one train per ten minutes during peak hours.
As of August 2017, private automobiles driving through the tunnel from the Kirisakian side are subject to a toll of 190 rin; this is roughly equivalent to 2.50 standard monetary units. The Kirisakian concessionaire for the tunnel, which is part of the Chiyoko Route and thus, by extension, the Hikari Expressway spanning most of Toyone Prefecture, is the state-owned Kirisaki Expressways Corporation.