D-ARCH spacer Gastprofessor Angelo Bucci





Switzerland presently follows the traffic policy of shifting the transport by heavy trucks on roads to railway transport. Towards this goal the capacity of the main traffic axis (north <-> south) is now greatly extended by the AlpTransit project. The key elements of this project are two long, deep base tunnels: the Lötschberg tunnel in the west and the Gotthard tunnel in the east (see Fig. 2; with exploratory adits Frutigen and Polmengo). The rock cover can reach 2.5 km and the lengths are considerable: 57 km for the Gotthard and 35 km for the Lötschberg.

Due to the thick overburden and the great lengths the expected geothermal potential issignificant.

The geothermal potential largely depends on the inflow rates and temperatures to be expected in the different tunnel sections. Whereas the rock/fluid temperatures can be predicted with relatively high accuracy (Rybach and Busslinger 1999, Busslinger and Rybach 1999, Keller 2002), the forecasts of the water inflows have a considerably range of uncertainty (ATH 1993). Therefore the estimated potentials at the portals can vary over a correspondingly wide range: Gotthard north portal: 4-23 MWt, Gotthard south portal: 4-19 MWt; Lötschberg north portal: 4-12 MWt, Lötschberg south portal: 4-7.5 MWt (Wärmenutzung Tunnelwasser BFE, 2002).

There are limitations by environmental regulation for discharging warm tunnel waters into rivers. The local rivers near the portals have only limited potential for tunnel water uptake; at most places cooling ponds/towers would be necessary to decrease water temperatures prior to disposal. Therefore the construction authorities show significant interest for a geothermal use of the tunnel waters, as well as the local communities like Frutigen at the Lötschberg north portal or Bodio at the Gotthard south portal. Besides space heating, innovative uses like heating of a tropical greenhouse in Frutigen (capacity demand: 2.7 MWt) are currently in discussion.

Furthermore, there is still ample space for innovative solutions, especially to utilize the warm tunnel waters in summer time. The planned tropical greenhouse in Frutigen is such an example. Further options are: spa-type establishments for wellness, fun and pleasure, aquacultures and the like. All of these applications are already being considered, but are still in a stage of infancy in Switzerland.



Geothermal use of tunnel waters – a Swiss speciality

International Geothermal Conference, Reykjavík, Sept. 2003 Session #5

L. Rybach [1] , J. Wilhelm [2], H. Gorhan [3]

1 Institute of Geophysics ETH Zurich; 2 Consulting Engineer, Pully; 3 Electrowatt – Ekono AG, Zurich




founding elements


Mountains and lakes are constants in the Swiss landscape.

There are two types of construction corresponding to them: tunnels and bridges.


north-south axis


The modern transposition of the Gotthard Mountain began in the 16th century with the construction of a stone bridge over the Schöllenen gorge. Since then, the Gotthard pass has been continually reconfigured in a history of constant struggle to overcome the massif.

With a route of 57 km, the construction of the Gotthard Base Tunnel is expected to be finished in 2016. It is an emblematic step representing a definitive north-south connection through the Alps.


The new Gotthard pass, key project for the AlpTransit railroad network, demands speed and efficiency. It compresses time and space; it shortens huge distances, approximates places, connects cities and, in this sense, tends to cancel the perception of the whole route.


Geothermal potential / environmental impact


The great geothermal potential of the 57km long and 1000m deep Gotthard base tunnel produces an important side effect: the tunnel is a source of hot water.


For an energy point of view, the hot water is sufficient to warm a great number of buildings located near the tunnel portals. Several studies are being carried out to exploit this possibility.


Environmentally, this source of hot water is a problem. In order to reduce its environmental impact, these warm waters must be retained and cooled down before being discharged into rivers and lakes. How to answer this question?




The cooling and retaining water devices at the tunnel portals compose an obligatory infrastructure to mitigate the environmental effects of such massive tunnel construction. This mechanism, however, does not compete with the possible geothermal use for heating nearby houses and buildings.

It rather allies to it. Actually such devices balance the whole system according to volume and temperature variation of the outflow water in each season.




Hot water tanks placed in sequence in order to decrease the water temperature are in direct relation with a subject that follows architectural history since the roman thermal baths [caldarium, tepidarium, frigidarium]. More than that, the baths are extremely well elaborated and studied topic within the Swiss context. [Stoffler, Johannes, ETHZ. Modernism for the People, Swimming Pool Landscapes in Switzerland To be published in: Modernism and Landscape Architecture]


Architecture and Infrastructure


The environmental effects of the Gotthard tunnel waters suggest an engagement between architecture and infrastructure, merging environmental conscience and technique with the program of leisure and public baths in Switzerland. Swimming pools or thermal baths will be the new portals of the Gotthard Pass.


Architecture and landscape


Site and program approximate architectural design elements to the surrounding landscape. In this case, the mountain and the lake are the genesis and final destiny of the projects


Again, stone and water are the raw and symbolic materials for the projects we invite you to do.



- Base material preparation

- Study of reference projects (thematic, swimming pools and thermal baths; and circumstantial, similar site conditions and formal language)


- Ticino visit.

A. Projects directly related to the studio:

[1]Gotthard’s south portal. [2] Monteceneri [3] San Gotthard Pass [4] La Claustra Hotel


B.Ticino architectural references


[5] Tunnel portals by Rino Tami [6] Young architect’s work from Ticino [7] Swimming Pools, Lidos and Thermal Baths [Centro visitatori AlpTransit, Lido Locarno, Centro Sportivo Tenero, Centro Sportivo Bellinziona, Lido Lugano, Lido Bissone, Piscina Comunale Mendrisio, Piscina Comunale Chiasso]



Modernism for the People: Swimming Pool Landscapes in Switzerland

Johannes Stoffler

To be published in: Modernism and Landscape Architecture 1890-1940. Studies in the History of Art. National Gallery of Art, Washington D.C.


Geothermal use of tunnel waters – a Swiss specialty

International Geothermal Conference, Reykjavík, Sept. 2003 Session #5

L. Rybach [1] , J. Wilhelm [2], H. Gorhan [3]

1) Institute of Geophysics ETH Zurich

2) Consulting Engineer, Pully

3) Electrowatt – Ekono AG, Zurich


Porta Alpina

Gion Caminada / studio ETHZ [2005]


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