Underground excavation wish list 09 Jan 2020

In the look back at the 2019 article and in the following article preparing for 2020, a question was posed in an effort to brainstorm further uses of underground space. The question was: If productivity could be increased and the cost of excavating underground space reduced significantly, and if tunnel length was not an issue, where would it be sensible to build underground facilities and tunnels?

Build down rather than up

There are many tunnel projects already suggested, some of them in advanced stages of feasibility study (Table 1) and the following are some other suggestions that inspire the greater, more creative and more urgent use of underground space infrastructure. Send us your thoughts to add to the list.

Earthscrapers: Build down instead of up. There are many different concepts being promoted and ITACUS, the Committee on Underground Space of ITA, the International Tunnelling and Underground Space Association, is promoting more imaginative and feasible concepts for creating underground living and working spaces and for facilities such as sensitive laboratories; underground farming; underground cemeteries, and underground long term storage banks.

Underground homes, hotels, offices, shopping malls, in hot and very cold climates where the underground temperature is naturally stable and comfortable. For example, the Coober Pedy underground homes in South Australia at the opal mining operations in a very hot climate, and the Helsinki and Montreal underground shopping malls with direct access to the metro stations for the very cold climates.

Underground hotel in Coober Pedy

More underground car parking garages in urban areas: Parking on both sides of narrow streets in urban areas is a serious issue and there are opportunities of having the entrances in local gardens or parks and the access going under the narrow parallel streets to have parking under each house, just beneath services and into or under basements, with the exit at the far end of the entrance for only one-way traffic and the link into each house via an elevator or a stairway into the kitchen or the garden. The parking garage for the Sydney Opera House in Australia is an example of one way traffic through the garage driving down through the helix to come up and out in the same direction to exit at the entrance portal. TBM manufacturer CREG has developed a machine for excavating such underground car parks, erecting precast concrete elements behind. The concept was an entry in the ITA Awards of 2019 in the Innovative Underground Space Concept category.

Doubling up existing undersea links: For example a road connection for the Channel Tunnel, more links under the Bosphorus (bridges are still very congested); fixed links from mainland to islands in the Mediterranean.

The Trans-Atlantic hyperlink floating tunnel concept which has been a concept for several decades.

More high-speed rail worldwide: High-speed rail is quick, easier, more time and energy efficient than travelling by air or by car for journeys of up to 500km distance and travelling at 200km/hr. That distance is greater with greater speeds on maglev or hyperloop systems.

More underground metros: A rule of thumb often quoted is that an underground mass transit system is needed for cities of more than 1 million population. Given that criteria, there is a lot to do, and that is before considering the tremendous amount of work needed in cities of both more and less than 1 million for sewerage and water supply in developing countries.

Sydney’s double helix car park

Tapping the icecaps and glaciers for fresh water: If the icecaps and glaciers are melting we should capture the fresh water to hold as a resource in underground reservoirs and delivery systems, rather than waste it into the sea.

More and more hydro schemes: Use fresh water for multi-purposes and help reduce carbon emissions by increasing hydro energy generation as the environmentally responsible alternative.

Let everyone buy quality drinking water in bottles, as many do nowadays in their homes, and turn current fresh water networks into good quality but less expensive grey water quality for flushing toilets, watering gardens, washing cars, washing clothes, and everything but drinking and cooking.

Underground transmission of all high voltage electricity cables: London in the UK leads the way with hundreds of kilometres of high voltage cable tunnels under the city. TBM manufacturer Herrenknecht won the award for innovation at the bauma trade show in Munich in April 2019 for its development of high-speed micro machines to create the underground links for carrying wind farm cables from the North Sea, where it is generated, to the south of Germany where it is needed.

More application of multi-use underground infrastructure: For example the SMART tunnel in Kuala Lumpur that is both a stormwater conduit to protect the city from serious flooding and a double deck highway for when the stormwater facility is not needed; water, gas, sewer, ground water conduits in Ashgabat, Turkmenistan; single TBM tunnels to accommodate both road and metro links in the same road + metro single tubes.

More stormwater facilities to protect sinking and drowning cities. Plan for Venice, Jakarta, Manila, Bangkok to have infrastructure like the SMART tunnel to be multi-use and used for stormwater protection only when needed.

Progress, with urgency, the desperate need for viable, safe, long long-term depository or repository storage of nuclear waste. This should be a universal imperative rather than a national issue to solve.

High-speed trans-ocean travel

More need to put ugly elevated highways and metros underground: The Cahill elevated highway that ruins the Sydney foreshore behind the Opera House is one example. Extension of the elevated highway went underground in the Eastern Distributor in the 1990s. The Hammersmith flyover in London should be a fly-under. Incredible multi-level stacked interchanges in big cities such as Shanghai and Taipei and Bangkok that get traffic up onto, and down from, highways in the air should have an underground alternative. The elevated trains in downtown Chicago and New York should be under the city. Elevated parts of London Underground that could now go underground and free up highly valuable urban land space.

Lots more reservoirs for big cities: They would have to be underground as no-one wants them taking up open green space. Or build the reservoirs further out and tunnel the water into the cities.

Quarries and mines: Ban all open cut strip mining of the landscape and put all quarrying and mining underground. Quarries and open pits are open scars on the landscape and cause noise and dust pollution as well as social health issues.

Find civil uses for worked out underground mines: There are examples of oil and LPG storage in old salt mines, but other uses could be landfill rubbish disposal and deposits for tunnel project muck.

Long tunnels to offshore oil fields and gas wells: Engineers in Norway are studying the feasibility of such undersea fixed links.

Tunnels under the sea to bring in electricity cables from ocean wind farms and tidal energy generators or from stations where sea water is converted to hydrogen for energy generation.

Remove all level crossings to grade separate road, rail and pedestrians to resolve a major safety issue. Do the same for road and highway intersections to avoid the long, air polluting idling at stop lights.

Ban open cut metro station and running tunnel construction in cities. Mined construction without disrupting the surface of the city has to be the way.

For just about everything that can be on the surface, there is an underground alternative. Productivity; speed of construction; difficulty of dealing with the ground as the host medium; cost; risk; willingness; social negatives; physiological problems of being underground; are all against these great ideas.

Add to the discussion and send us your views, suggestions and feedback.