In this article, large technical systems are analyaed from three perspectives. First, the global characteristics of LTSs are emphasized, Second, LTSs are identified as those technical systems that are able to structure social perception of space and time. Finally, LTSs are defined as systems constituted at the interface of several subsystems. These claims are illustrated with several examples. More attention should be devoted to the interaction mechanisms between the various factors that shape the development patterns of LTSs. An approach based (...) on composition of factors is therefore stressed. (shrink)