Large scale Socio-Technical Systems (LSTSs) operating over networks (such as the electricity system , the railways , the airspace system , Internet…) have radically changed our daily lives over the past few decades and also transformed the way our Societies work . They represent a phenomenon that is conducive to enthusiasm , which contributes to the democratization process of societies everywhere, offering new features and services over the coming years , consequences and sources of new techniques and technologies : in this light , LSTSs appeared as a natural field for investigation by our Academy .

They have undergone considerable development already (and continue to do so) not only in terms of technological progress in their on area (photovoltaic arrays to produce electricity commercially , high speed trains (TGVs in France) for rail transport , mobile phones for inter-personal communications…) but also thanks to new ICTs , themselves being sources of change in the way they work and the scope of services they offer .

Taken together they now account , directly or indirectly , for a non negligible fraction of household budgets . Hundreds of thousands of jobs in France depend on these LSTSs , and we can count in millions in Europe and the World . Development has an impact on land planning and the level of attractiveness of regions , areas , cities… These points in common are not , however , the only factors to be considered and for this reason the choice made , viz . , to study the LSTSs as a whole , beyond any specific differences , can prove interesting .

A further reason to study LSTSs lies in the fact that even if globally speaking their operation is deemed satisfactory and has adapted itself remarkably over the years — at least in Western countries — it nonetheless remains that dysfunctions can have serious consequences . This indeed is why these systems in Anglo-Saxon terminology are referred to as “critical infrastructures” . It is therefore useful to try to analyze the main factors of change , to try to deduce certain “laws” and to make some proposals to counter possible risks . This approach seemed all the more relevant
that most members of the NATF-WP became convinced , as the studies progressed, that most of the large scale systems are becoming more and more fragile.

The NATF LSTS WP has noted that even the least developed countries are now endeavouring to develop similar systems , to the extent that they are now vital to their future . For countries like these , many additional questions arise , appertaining to technical , economic , social and political issues ; these questions call for more studies .

The core text sets out the main factors for change for LSTSs and the proposals drafted by the NATF’s WP that the Academy addresses to politicians , regulators , industrialists , in short , the actors of the systems , without any exclusion of the citizens/users/clients who have their role to play .
The notes , comments in the appendices (referenced in the text) are grouped together in fine .
Our document ends with a set of Internet sites that will enable readers who are interested to follow up their studies about LSTSs.