Cybergeo (Oct 2018)
Contribution de la future ligne ferroviaire à grande vitesse Tours-Bordeaux au développement des réseaux des villes, une évaluation par le potentiel de contact
Abstract
This contribution aims at presenting and implementing an indicator called contact potential on a set of cities touched by the opening in 2017 of a new high-speed rail line between Tours and Bordeaux. Two contributions are presented, on the methodological side, and on the application side.Firstly, on the methodological side, this contribution develops a new analysis of the relationships between cities and transports under the contact potential indicator viewpoint. An obstacle to this type of approach is solved: in order to assess the situation of the operation of a new portion of a high-speed rail line, it is necessary to build a complete and realistic future timetable. We have achieved this modelling by using ad-hoc developed tools that represent the timetable information under a form similar to that of the timetable proposed to travellers by the transport operators. This approach allows modifications to the existing circulations of trains on the new line and enables the report of travel time reduction on the trips that extend beyond the new line, which is one of the particularities of the French high-speed rail system. It becomes possible to build a realistic transport supply and to introduce it in a database in order to simulate a future transport supply.On the application side, this simulation of the effect of a new transport infrastructure on the contact potential brings elements of analyse some of them were expected and a few others were not. It is no surprise that the cities that benefit the most from the new supply are directly linked to the layout of the new line. One could have assumed that the new line would benefit to tangential linkages in western France for instance between Bordeaux and Nantes; but our results do not show this. New linkages out of the Bordeaux-Paris axis emerge, but they extend beyond Île-de-France, and on the high-speed rail network, to the east and the north. The evolution of the contact potential mainly produces new linkages that are based on the high-speed rail network as a whole, to the north and the east beyond Paris. The improved linkages using the conventional lower speed railway network are much less developed, and the tangential relationships on the Atlantic façade do not benefit from this new transport supply as much as we could have anticipated.
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