Résumé EN : In this paper, the authors propose a framework which enables them to analyse the economic impact of new highway links between Montreal and eleven surrounding cities, specifically the impact on the economic structure of those cities. The authors observe a relationship between changes in accessibility (to Montreal) and economic structure. Greater accessibility resulting from new highway construction seems generally to favour industrial growth and diversification, although a very rapid and radical change in accessibility can also have negative consequences on the short run. The service sector appears particularly sensitive to changes in accessibility. The authors observe a cut off point of one hour's travel time: as soon as city falls within this travel-time zone its service sector (especially more the sophisticated services) systematically declines. Finally, the authors conclude that the precise nature of the impact of increased accessibility to Montreal is largely a function of the original economic structure of the city concerned: certain structures are more sensitive to changes in accessibility than others.
Résumé EN : In this paper, the decentralized economic allocation of a common property resource is fully characterized in a dynamic framework. Because of the externalities involved, this mode of allocation is shown to be inefficient. The extent and the causes of this inefficiency are discussed, with special emphasis on a kind of externality herein called the "appropriability". Finally, economic policies involving taxation, subsidy and user charge which purpose to bring about the social optimum are pointed out.
Résumé EN : This historical note describes from Sidgwick on the evolution of the concepts related to the interdependencies of economic agents outside markets. In a first section, we show how the concept of externality introduced by some precursors had later to reemerge from the confuse discussion of "empty boxes". The second sector clarifies the distinction between two avenues of research, the first one associated with pecuniary externalities, the other one associated with technological externalities. Coase's criticisms of Pigouvian policy are developed in section 3. In a last section we gather the main results obtained recently by economic theory in this field. In particular we discuss the difficulties of the creation of artificial markets, the second best approaches often needed in a Pigouvian policy, results of game theory in models with externalities, planning with externalities.
Résumé EN : This paper presents a price model of the Input-Output variety. This model computes the changes in the production costs and the prices of goods resulting from changes in the prices of primary factors and imports and changes in indirect taxes. It assumes that all such changes are transmitted in whole and without delay to the users of goods. It is very close in spirit to the price model developed by Statistics Canada but it offers more general possibilities than the latter.