All geographical distances are optimal

International audienceTriangular inequality is one of the four mathematical properties of distance. Its respect derives from the optimal nature of the measurement of distance. This demonstration (L'Hostis 2016, 2017) reveals key aspects of distances and geographical spaces. We develop this argument by investigating the idea of the optimality of distance through a mathematical and geometric discussion, and by dealing with empirical approaches to applied geography.The first part of the paper explores the consequences of considering that the mathematical property of triangle inequality is always respected. In fact, no violations of triangle inequality are observed in geographical spaces. The study of the optimality of distances in empirical approaches confirms the key role of the property of triangle inequality. The general principle of least-effort applies for most movements and spacings. In addition, however, trajectories with multiple detours, like those of shoppers, runners and nomads, are optimal from a certain point of view. This is also the case for excess travel, i.e. a situation of disjunction between an optimum as perceived by a person in movement and an optimum as perceived by an external observer. Any movement, any spacing within and between cities and in geographical space in general, exhibits a form of optimality, and all geographical distances are optimal

The shriveled USA: Representing time-space in the context of metropolitanization and the development of high speeds

International audienceOn the one hand the present globalisation process has only been made possible through a reduction of time-distances allowed by high speeds, and particularly through the development of the air mode. On the other hand the metropolitanization process seen as the urban counterpart of globalisation is deeply associated with the development of air platforms. Understanding distances between places is a fundamental task for the geographer, while the representation of distances constitutes one of the major functions of cartography. Among the types of maps invented to represent time-space anamorphosis have been supplemented in the 1990's with time-space relief cartography. This paper proposes a representation of the time-space relief of the USA considering terrestrial and air modes. This last point constitutes a key innovation among this type of cartography, giving the possibility to build a representation of global time-space. The metaphors associated with the images proposed are then discussed evocating the shrinking, the crumpling and finally the shriveling of time-space. The shriveling metaphor renders account of the complicate contraction/dilatation movement that thigh speeds provokes on space and allows for a rich interpretation of the time-space relief map of the USA in the perspective of the processes of globalisation and metropolitanization

A Transport network for a City network: Analysing the quality of the public transport service in the Nord-Pas-de-Calais region

International audienceThe objective of this contribution is to establish a method linking the performance of the regional rail transport network and two principles of territorial organisation around a central pole (monocentric option) or in a city network (polycentric option), applied to the Région Nord-Pas-de-Calais in France. The first step here is to define a set of urban centres, on which the spatial organisation principles are applied. The analysis of the quality of transport service is established from an indicator expressing the possibility to accomplish daily trips between two cities with a ‘fast train at the right moment' from home and back. The method allows us to analyse the answer of the transport system to expressed or potential demand, but it is also used to analyse the spatial organisation of the system and to link it to spatial planning objectives. From this point of view, the organisation of the Région Nord-Pas-de-Calais appears more to exhibit a monocentric pattern around Lille than to lend significant support to the polycentric idea. The promotion of such a polycentric organisation will then only be possible through a voluntarist regional planning policy

Définir l'accessibilité intermodale

Ce chapitre a pour objet de présenter les notions d'accessibilité multimodale et d'accessibilité intermodale. Nous proposons dans un premier temps de définir l'accessibilité. Dans le domaine des transports urbains mettrons l'accent sur les transports collectifs, en précisant les particularités de leur fonctionnement qu'il est nécessaire de prendre en compte pour comprendre l'accessibilité qu'ils génèrent. Ensuite nous aborderons les questions de multimodalité et d'intermodalité. Nous finirons ce chapitre en exposant une application impliquant des mesures d'accessibilité intermodale sur le terrain d'une région urbaine

"Potentiel de contact" des villes

National audienceCet article présente une analyse de la connectivité des villes françaises en utilisant des mesures du "potentiel de contact" des villes. Une illustration des effets à attendre de la réalisation de la ligne TGV tours-Bordeaux est présentée

La ville orientée vers le rail et l'intermodalité

Dans les villes européennes d'aujourd'hui, la tendance à la périurbanisation et le fait que la forme urbaine est de plus en plus polycentrique, conduisent à penser le développement urbain dans un cadre plus vaste. Dans la construction des régions urbaines, il est intéressant d'examiner dans quelle mesure le réseau de transport ferroviaire constitue ou pourrait constituer l'armature principale à partir de laquelle s'organise le système de transport alternatif à l'automobile. C'est dans ce contexte que le programme Bahn.Ville vise à étudier le renforcement ou la création d'une forme urbaine qui tire parti des potentialités du réseau de transport ferroviaire, à améliorer l'articulation des interventions sur de multiples domaines - foncier, renouvellement urbain, transport, déplacements, services - qui concourent à la production de la ville. Le programme Bahn.Ville intitulé " Urbanisme orienté vers le rail et intermodalité dans les régions urbaines allemandes et françaises " est un ensemble de recherches et de recherches actions qui s'est présenté en deux phases principales, inscrites dans le cadre de la coopération bilatérale DEUFRAKO. Une première phase intitulée Bahn.Ville 1 s'est déroulée de 2001 à 2004 et a mis à jour un ensemble de principes et de conditions favorables à une meilleure articulation entre urbanisme et réseaux ferroviaires en s'appuyant sur une analyse de cas en France et en Allemagne autour de lignes ferroviaires revitalisées (Pretsch et al. 2005). Après une période intermédiaire de recherche de sites et de partenariats locaux le projet Bahn.Ville 2 a été mené de 2007 à 2010 avec le double objectif d'affiner les enseignements de Bahn.Ville 1 et de tester leur mise en œuvre sur les terrains de deux régions urbaines : l'une française autour de la ligne St-Etienne-Firminy, l'autre allemande focalisée sur la Taunusbahn de la région de Francfort (Wulfhorst 2007). Le chapitre présente une synthèse des deux projets allemand et français pour caractériser un projet d'urbanisme orienté vers le rail. Les enjeux de la thématique sont ensuite discutés, notamment en lien avec le film de C Lallier sur le sujet et avec les indications issues de la conférence international BUFTOD organisée en 2012

Public transport in cities and regions, Facing an uncertain future?

This chapter outlines the main aspects of British and French transport policies, especially for urban and regional public transport, against this background. The first section reviews the development of major transport policy instruments in recent years. Following sections consider some specific aspects, including the roles of regional agencies and local authorities, the links between transport and spatial development, and the administration of public transport. Each section contains a brief review of the British and French approaches and some comparative remarks. A concluding section draws out some key points of similarity and difference

A transport network for a City network in the Nord-Pas-de-Calais region: linking the performance of the public transport service with the perspectives of a monocentric or a polycentric urban system

The objective of this contribution is to establish a method linking the performance of the regional rail transport network and two principles of territorial organisation around a central pole (monocentric option) or in a city network (polycentric option), applied to the Région Nord-Pas-de-Calais in France. The first step here is to define a set of urban centres, on which the spatial organisation principles are applied. The analysis of the quality of transport service is established from an indicator expressing the possibility to accomplish daily trips between two cities with a ‘fast train at the right moment’ from home and back. The method allows us to analyse the answer of the transport system to expressed or potential demand, but it is also used to analyse the spatial organisation of the system and to link it to spatial planning objectives. From this point of view, the organisation of the Région Nord-Pas-de-Calais appears more to exhibit a monocentric pattern around Lille than to lend significant support to the polycentric idea. The promotion of such a polycentric organisation will then only be possible through a voluntarist regional planning policy

A transport network for a City network in the Nord-Pas-de-Calais region: linking the performance of the public transport service with the perspectives of a monocentric or a polycentric urban system

The objective of this contribution is to establish a method linking the performance of the regional rail transport network and two principles of territorial organisation around a central pole (monocentric option) or in a city network (polycentric option), applied to the Région Nord-Pas-de-Calais in France. The first step here is to define a set of urban centres, on which the spatial organisation principles are applied. The analysis of the quality of transport service is established from an indicator expressing the possibility to accomplish daily trips between two cities with a ‘fast train at the right moment’ from home and back. The method allows us to analyse the answer of the transport system to expressed or potential demand, but it is also used to analyse the spatial organisation of the system and to link it to spatial planning objectives. From this point of view, the organisation of the Région Nord-Pas-de-Calais appears more to exhibit a monocentric pattern around Lille than to lend significant support to the polycentric idea. The promotion of such a polycentric organisation will then only be possible through a voluntarist regional planning policy