Modeling and Evaluation of the Long-Term Effects of the Grand Paris Express

The future Grand Paris Express (GPE) network aims to improve daily mobility and the accessibility of certain areas in Île-de-France, by connecting the city center and the main employment and living hubs of the Region.

Beyond its immediate impact on modal choices and emissions, the project will have structural effects on the spatial organisation of the metropolis: distribution of activities (households, businesses, services), urban densities, and motorisation rate, and will enable potential synergies with other transport policies. It is within this framework that the Société du Grand Paris (SGP) commissioned a study focusing on the long term (horizon 2050) and taking the interactions between land use and transport into account.

Objectives

The study aimed to simulate the effects of the GPE on spatial organisation and mobility in the metropolis, to produce spatial, modal, and environmental indicators, to evaluate different scenarios, and to compare their effects.

Methodology

An integrated land use–transport model was developed using the TRANUS software. This model combines spatial economics, supply-demand equilibrium, and microeconomic random choice theory to simulate the location of households and jobs, as well as mobility behaviors. The simulations provided detailed indicators (densities, daily distances traveled, time spent commuting, modal split, vehicle-km, emissions), subsequently feeding into a carbon and socio-economic assessment.

Results

The approach allowed for the evaluation of the long-term benefits of the GPE, by integrating interactions, synergies, and ripple effects on urban dynamics.