The first hurdle that the mooted Gozo to Malta tunnel project would face, if it ever comes to fruition, would be the environmental impact. Marine biologist Alan Deidun explained that a substantial area of the Channel between Malta and Gozo is covered by protected habitats at EU level.

While seagrass meadows (posedonia) cover a substantial area, there are also a good number of caves and reefs.

“The local context is very important in discussions on the subject and comparisons with tunnels situated in other countries such as Norway and Denmark are difficult to make,” he pointed out.

The necessary blasting and drilling will have a huge impact on the seabed while underwater noise generation will affect species including dolphins and fish found in the Channel. Noise generation is one of the major elements being taken into consideration in studies for the proposed off-shore wind farm at Sikka l-Bajda.

If a bridge is considered, the effect on the substantial amount of birds of prey using the Channel to flock and the impact on the seabed will have to be assessed.

Dr Deidun said the damage in constructing a bridge would probably be higher than in excavating a tunnel because of the supports necessary to hold up the structure.

Underground tunnels in Malta

The eight-kilometre Delimara to Marsa underground tunnel, which is also Malta’s longest, was €9.3 million in the making. Inaugurated in February 2008, it is five metres high and four metres wide and runs between 20 and 40 metres underground.

More than 40% of the tunnel’s cost resulted from an impasse contractors encountered in an area beneath Zejtun and Tas-Silg, Marsaxlokk, where immense boulders, previously thought to have been solid rock, were found.

The entire stretch had to be reinforced with concrete before drilling could continue. The mere 500-metre stretch took two years to complete at an agonising pace of one to two metres per day.

Another service tunnel links Mosta with Qormi in a 6km stretch. Works took 24 months and cost €1.6m.

Enemalta is undertaking and planning the excavation of more tunnels to join its distribution centres.

Meanwhile, works are currently ongoing on 1.8km of sewer tunnels in the south of Malta. The estimated cost is some €3.7m.

With regard to vehicular traffic, only the Santa Venera tunnel has so far been excavated.

Denmark opts for sea tunnel to Germany

Denmark is to build an underwater tunnel to Germany, cutting road and rail journey times between western Europe and Scandinavia.

BBC News last week reported the Danish parliament rejected plans for a bridge across the Fehmarn Strait in favour of the tunnel, deciding it would be safer and greener.

The tunnel will be built between the Danish island of Lolland and the German island of Fehmarn. Both islands are already connected by bridges to the rest of their respective countries.

Oresund cable-stayed bridge from Denmark to Sweden

The 16-kilometre Oresund cable-stayed bridge, linking Denmark with Sweden was a dream for generations.

It opened officially for business on time and on budget on 1 July 2000 and its cost reached almost €2.2billion covering the bridge, tunnel, and the artificial island.

It took a monumental engineering effort pushing technology to absolute limit in establishing new world records as it included building the largest submerged concrete tunnel in the world.

Moreover, Oresund is the world’s longest double deck bridge for car and rail traffic and included the tallest free standing double leg pile-ons on any bridge, anywhere in the world.

Before constructing it, engineers had to build from scratch an artificial island 9km around. This had to be high enough for ships to pass under and strong enough to carry speeding trains and cars.

They used the largest floating crane on earth, capable of lifting more than 7 million kilogrammes – the equivalent of 30 Boeing 737.

During the first five years in operation, over 44 million people crossed the Oresund link going to new homes, to new jobs or just exploring.

Its 51 bridge peers have become artificial reefs providing plants and shelter for fish and marine life. Environmentalists originally against the project have documented an explosion of life.

Seikan Tunnel, Japan

The longest in the world and one of the most impressive engineering projects of the 20th century, connects Japan’s main island of Honshu with the island of Hokkaido, with a 53.8km long tunnel. Some 23.3km of the tunnel lie under water beneath the Tsugaru Strait.

It was built between 1964 and 1988 by Japanese National Railways but is now only nominally used since air travel is quicker and more economical than when construction began.

Channel Tunnel

The Channel Tunnel is a series of three tunnels (two carrying, one service tunnel) linking the southern coast of England to the northern coast of France.

The tunnels are 50km long, with an undersea section of 39 km, making it the longest undersea tunnel system in the world.

The project was privately financed and continues to be privately operated. The estimated £4.8 billion total cost of the tunnel turned out to be a serious miscalculation, as the cost ballooned to almost £10 billion by the time it opened in 1994 – more than double the original estimates.

It cost enough money to make the Golden Gate Bridge in America 700 times over.

The deepest point of the tunnel is 250 metres below the surface of the water.

Frequent problems nearly caused the project to be abandoned several times. The unexpected wet ground caused severe problems during the building even though it had been surveyed before the drilling and said to be relatively dry. It eventually turned out to be a nightmare. Lives were at risk.

Concrete slabs could also not be placed properly because of the wet ground and the 100 locomotives being used had to be redesigned.

Faroe Islands underground tunnels

Situated in the heart of the Gulf Stream in the North Atlantic, the Faroe Islands lie northwest of Scotland and halfway between Iceland and Norway.

In the Faroe Islands, there are two sub-sea tunnels between Vágar and Streymoy (opened in 2002) and between Eysturoy and Borðoy (opened in 2006). Both tunnels are partly user-financed.

The first tunnel is 4.9 kilometres long – nearly as long as the point to point distance between Malta and Gozo.

The second tunnel, 6.3 kilometres long, cost some €48m. The deepest point is 150 metres below sea-level and it is 10 metres wide.

By means of the tunnel, 85% of Faroese people are geographically connected.

Facts

The Channel Tunnel cost enough money to make the Golden Gate Bridge in America 700 times over.

By means of a tunnel, 85% of Faroese people are geographically

connected

The 53.8km long tunnel connecting Japan’s main island of Honshu with the island of Hokkaido is the longest in the world