Ever since the world’s first recorded underground aqueducts were constructed in ancient Egypt, engineers have been making suggestions for innovative tunnels. Many of these ideas were ridiculed or dismissed as being ahead of their time, but a surprising number now qualify for the Hall of Fame. The classic case, of course, is that of the Channel Tunnel, which was in the Theatre of Dreams for 200 years. The following list is not intended to be comprehensive, and readers are invited to add their own suggestions. Who knows where this may lead? Perhaps, in another 200 years, you will be credited as a visionary.

Low Road to Orkney - a ferry story
Proposals to build a 11.2 km long subsea tunnel across the Pentland Firth linking Orkney to the Scottish mainland were presented to the Orkney council's transportation and infrastructures committee on 3rd February, 2005. Council members had been greatly impressed on a visit to Norway, where 24 subsea crossings have been built to date at a current cost/m of €7,500. The proposed tunnel investment of €150 million will be compared to the cost of ferries, which must be replaced every 20 years at around €45 million apiece. Unfortunately, the UK builds only one subsea tunnel every 100 years, and the Irish Sea tunnel was suggested first. Perhaps the Orkney tunnel plans should be placed in a time capsule and buried at Stonehenge.

Sunda Strait - eruption vs drowning?
The proposed twin-tube tunnel that will connect Java and Sumatra across the Sunda Strait is to span 33 km of some of the most seismically active strata in the Earth's crust. The island of Krakatoa, located in the Strait, provided the largest witnessed explosion in recorded history on 27th August, 1883 killing 36,000 people, and heard as far away as Australia. However, some 13 to 20 million people cross the busy waterway each year, and this figure is expected to grow to 40 million by 2020. A tunnel will cost US$3-4 billion, requiring 8.5 m-wide x 6.6 m-high tubes located 40 m below the seabed. Visit www.nusantaratunnel.co.id Submitted by reader dvdhindle@aol.com 36/04.

Chillada's Cuboid - creating a volcanic void
Before renowned Spanish sculptor Eduardo Chillada died in 2002, he laid plans for a 65 m-long x 50 m-wide x 45 m-high cuboid chamber to be excavated near the apex of Mount Tindaya, on the Canaries island of Fuerteventura. The smooth-walled cavern will have a flat roof pierced by two light wells, through which the sun and stars may be viewed. The excavation is thought to be technically feasible, although the massive trachyte of the area exhibits a tendency to spalling, and there are igneous dykes to complicate matters. As a result, visitors to Chillada's Cuboid could end up seeing stars without the need for the light wells! The only comparable structure of similar span is Norway's Gjovik ice cavern, which is located in dependable Baltic shield granite/gneiss, and has a sensible arched roof. See tunnelbuilder Hall of Fame entry. 27/04.

TBMs - taking over the world
Moore's Law for TBMs claims the number of TBMs working at any given time doubles every decade. There were maybe 5-6 in the early 1960s, 10-15 in the early 1970s, 25-30 in the early 1980s, 50-60 in the early 1990s, and around 125 in 2003. Will the curve continue? Will there be 250 in 2015, 500 in 2025, and 1000 in 2035? Why not? People know how to make and use the machines properly by now, and capital and operating costs are falling continuously. Nature is bountiful to well-posed problems, and there is a never-ending list of applications out there, of which highways and megacity infrastructure are the biggies.
I do understand there will probably not be a million TBMs working in 2135. fhapgood@pobox.com 45/03

Porta Alpina - world's deepest railway station
The villagers of Canton Graubunden, which straddles the centre section of Switzerland's 54 km-long Gotthard tunnel, have come up with a brilliant scheme to popularize their region. They want to convert the 1 km-deep emergency station at Sedrun into a train stop at a cost of €25 million. With Milan and Zurich just an hour away in each direction, the new Porta Alpina station would attract 60,000 tourists/year, improving incomes and property values. Indeed, the station itself would become a major attraction! Sadly, Swiss Railways don't agree, and will fight the proposal. After all, the purpose of the Gotthard is to bypass Switzerland, not invade it! Visit www.visiun-porta-alpina.ch 44/03.

London Tube - putting a price on global warming
Following several years during which expensive consultants have failed to come up with the solution to summer cooling problems on the London Tube, the mayor has decided on a competition with a £100,000 prize for the best idea. Amongst suggestions to date are: issuing free ice lollipops to each traveller as they enter the system; bringing in trainloads of snow, which passengers can play with during power cuts; refrigerating stairway banisters; pasting up large pictures of Alpine scenes; moving the Tube north to Scotland; tapping and circulating rising groundwater, which could then be used for flushing the toilets; and our favourite, removing the tracks, filling the tunnels with water, and replacing the trains with Venetian gondolas for a faster service. Unfortunately, because these ideas have been made public, they have been scrapped under clause 13 of the competition confidentiality rules.
If you think you have the solution, visit www.news.bbc.co.uk/1/hi/magazine/3069037.stm or www.tube.tfl.gov.uk/content/FAQ/ac_100k.asp. 37/03.

Leaving LA - moguls to move offshore?
It is reported from Hollywood, CA that film moguls are getting together to revoke the National Park status of Santa Catalina Island off the Los Angeles coast. They want to build a paparazzi-free utopia for themselves, connected to the mainland by a Disney-style glass tunnel under Santa Monica Bay from the I-10 highway. The general idea, according to a local correspondent, is that their limousine commute is "full of fishes and sharks and stuff..." Early planning calls for 35 in-thick optically clear, high silica, low iron glass, fused and finished to completely remove any evidence of joints. Financing is expected to come from the moguls themselves, but they have yet to agree to hypothecate a proportion of their average $20 million/movie. More from tom_kasper@yahoo.com

Underpassing Austria - a night truckers dream?
A feasibility study was presented at the June, 2001 ITA conference in Milan for the proposed Federico II di Svevia route, a 350 km-long connection between Brescia, Italy and Stuttgart, Germany promoted by ANAS, the Italian motorway owners. Some 170 km will be in double-decked twin tunnels, with the upper deck for road and the lower deck for rail. TBMs with 20 m diameter will be required for the following tunnels: Guglielmo (I), 23,020 km; Breno (I), 8,150 km; Adamello (I), 11,770 km; Pagano (I), 8,790 km; Bormio (I), 17,720 km; Cristallo (I), 26,320 km (new world longest); Muta (I-A), 25,660 km; Hexenkopf (A), 16,660 km; Perseierspitze (A), 16,410 km; Krottenkopf (A-D), 16,810 km. Austria will be bypassed in tunnel, so may feel able to lift its ban on night trucks. The new Italian transport minister is Prof Pietro Lunardi, who is a prime mover behind the Trans-Apennine railway, a project once thought equally impossible to finance. With a little guidance from European Union president Prodi, himself an ex-premier of Italy, who knows? Submitted by eazagor@infinito.it Visit www.rocksoil.it and www.enteanas.it 27/01.

Lake Michigan Underpass - avoiding the Windy City
A tunnel has been proposed to connect the Lower Peninsula of Michigan with Wisconsin, so that vehicles could make the trip across the big lake in about an hour, as opposed to the six hours it now takes to cross the lake via Chicago, IL and Gary, IN.
The shortest route is 84 km between Big Sable Point, north of Ludington in Michigan, and a point north of Two Rivers in Wisconsin. The preferable alignment is substantially longer, between Milwaukee and Muskegon. The current alternatives are driving around the south end of the lake, through Chicago, or taking a ferry, which only runs in summer. The politics of connecting two States are an impedance, but, as traffic congestion gets worse around Chicago, the idea will look more and more attractive! Jack Decker jack@novagate.com 26/01.

Sixties TBM - Jet Mole to the rescue!
International Rescue owns one Jet Mole, which is used to burrow beneath the earth to perform subterranean rescues. The Jet Mole is a two-component machine, comprising a manned yellow cylinder with a big revolving drill bit located at the front, which is carried into position by a blue-coloured tracked trolley. The trolley is remotely controlled and features a ramp to elevate the Jet Mole to the required angle for drilling into the ground. Visit http://tv21.simplenet.com/productions/thunderbirds/tbs.html and blame Fool's Day contributor hprsite2@singnet.com.sg 14/01.

Nuclear Subselene TBMs - lunatics on the loose!
A Texas A & M study conducted for NASA and released in May, 1988 recommended the use of a lithium cooled nuclear reactor as the power source for a TBM that would mine the living space for the first settlers on the moon. The cone-shaped machine was expected to melt its way through the lunar subsurface, plastering the liquid rock on the tunnel walls to form a glass-like ceramic lining. Curiously, this piece of space fiction goes on to recommend the use of conventional dumptrucks for carrying surplus rock out of the tunnel! Visit www.abovetopsecret.com/moontunnel.html for a greater insight into how American tax dollars were being spent in the late twentieth century. 07/01.

Japan-Korea Fixed Link - friends across the sea?
When the Japanese finally run out of places in which to tunnel on their own soil, this could provide their next megaproject. The distance across the straits between the two countries is more than 120 km as the crow flies. However, the Moonies sect, who first proposed this tunnel as part of their Friendship Highway linking east to west, envisage a slightly longer installation. When you have an hour or so to waste, find out all about their barmy ideas with a visit to www.iijnet.or.jp/IHCC/hist.html 05/01.

AlpTransit - the most expensive dream
The Swiss answer to their through-traffic problem is to put it on the railway. AlpTransit will provide the two base tunnels needed for speedy trans-alpine connections: the 9.2 m diameter x 56.9 km Gotthard and the 9.4 m diameter x 37 km Lotschberg. With depths of cover up to 2,000 m and rock temperatures as high as 50 degrees Celsius, there will be problems. The Gotthard job will be let in five contracts and will take ten years. The whole AlpTransit scheme, which includes the work required for the Bahn 2000 installations, will cost $20 billion. For the moment, exploration shafts and drives are underway against a background of a referendum having voted in favour of the full scheme. Sept 1998.

This project is rapidly moving from dream to reality. Keep pace with developments at ch/17-22. 07/05.

Bering Strait Crossing - candidate for a strait jacket
Suggestion put forward in 1991 for railway between United States and Russia by tunnelling 35 km from Seward peninsula in Alaska to a shaft on Little Diomede island in mid-Strait, onwards to a shaft on Big Diomede island, and then a further 35 km to Uelen on the Chukchi peninsula in Siberia. Design similar to the Channel Tunnel. Unlikely to happen because of requirement for 3,000 km rail link to join up with Canadian network and another 4,320 km to reach Russian railhead. Besides which, there is no good economic reason to join two sets of frozen wastes.

Straits of Gibraltar - joining Africa to Europe
Of various proposals put forward over the years, the current one is the first to result from inter-governmental discussions between Morocco and Spain. A 50 km tunnel is envisaged, with 28 km under the seabed with ground cover of up to 100 m. The route is from Punta Paloma to Tangiers, relieving the port of Algeciras, which is grossly overloaded at times as workers move between North Africa and the European Union. 1992 cost estimate was Pta2,000 million. A company called SECAG is progressing the proposal.

SwissMetro - sucking between stations
Scheme to connect cities in Switzerland by a high-speed vacuum tube. Has taken a back seat while AlpTransit gets under way, but will certainly be revived.

Pompton/Passaic - itself a fifty year event
Since 1939 proposals have been put forward for controlling floods in north-eastern New Jersey, the latest of which was a dual inlet tunnel diversion plan in 1988 by the U S Corps of Engineers. It involves a 21.7 km-long, 11.9 m-diameter concrete-lined tunnel to convey floodwater from the Pompton river to the Passaic. The tunnel would run some 37 m below the level of the riverbeds and would pass 140 m beneath the Watchung mountains.

1881 Channel Tunnel - a Victorian joke
Working for Sir Edward Watkin’s South Eastern Railway Company from a shaft at Shakespeare Cliff, Kent in 1881, Beaumont and English advanced their exploratory drive more than a kilometre at rates of up to 30 m/week using their 2.1 m-diameter compressed air driven TBM. When the 1987 Channel Tunnel intersected this drive, it was found to be still in good order. This begs the question: could the Victorians have completed the Channel Tunnel? The answer is, of course, negative. The Beaumont TBM was an open machine and would have been swamped at the first sign of water, of which there was plenty. Also, because of the lie of the chalk marl, which is the most amenable tunnelling stratum under the Channel, it would have been impossible to lay out a crown drive, so pumping from the face would have been a problem during construction. The logistics of muck removal and concrete transport would in any case have defeated the Victorians, because the proposed distances outran all current technology. At the rates that would have been achievable, the project would have soon run out of cash.

Second Channel Tunnel - Elizabethan joke?
Eurotunnel, holder of the Channel Tunnel operating franchise, is expected to put forward a viable scheme for a second Channel Tunnel or risk losing the option. At the last time of asking, it was said that this would be a driverless freight tunnel. If they don’t do it, somebody else will!

Immersed Tube to Ireland - best discussed over a Guinness
Lunatic idea for a tunnel on the floor of the Irish Sea was floated in 1998 at a time when Ryanair was offering flights from London to Belfast at £29 for two seats.

La Engana - Spanish mushroom farm
This tunnel was built in the 1930s as part of the railway to connect Santander to Spain’s Mediterranean coast. The track was never laid, but the tunnel is reported as still in good shape and being used for growing mushrooms. Despite the time lapse since its construction, La Engana is still referred to by the local politicians whenever railway extensions are mooted.

Taiwan Strait Crossing - politics defeats reality
In 1998 a symposium held at Qinghua University in Beijing and co-sponsored by the University of Taiwan discussed the feasibility of a 144 km tunnel between Pingtan island off SE China and Xinzhu in north Taiwan. Projected cost US$174 billion. Dream on! Expert opinion from Professor Wu Zhiming at Qinghua.

Baltic Circular - not gauged for success
A voluntary study by the Helsinki-Tallinn Society has come up with the answer to transportation difficulties between the Baltic states of Finland, Estonia and Russia. The Baltic Circular will connect all three by railway, with tunnels under the difficult bits, one of which is the Baltic Sea itself. The latter will be crossed by 40 km twin tunnels that will require 20m² TBM pilot tunnels from which pregrouting of the running tunnels can be undertaken. Unfortunately, the Finnish railway gauge is wider than the European standard, so something will have to change before this wet dream can start its metamorphosis to concrete nightmare.