This simulation model of mobility scenarios on the metropolitan scale assesses the economic, social and environmental impact of different transport policies. This includes pricing measures and changes to the mobility offer.

The STEM model, developed since 2017 at the École des Ponts ParisTech, under the direction of Fabien Leurent, is a strategic model of mobility on the scale of a metropolitan urban area. It represents the main challenges of mobility in such a territory, in terms of social impacts (service provided to users, accessibility of places), economic impacts (quality of service, fares and revenue, production costs and financing) and environmental impacts (noise, air pollution, energy and greenhouse gases).

STEM is a technical and economic model, intended to:

  • quantify the different issues;
  • simulate states of equilibrium between transport supply and mobility demand;
  • seek out optimised states of the system by calculating action variables which optimise an objective function while satisfying imposed constraints.

The typical application is to seek a plan for the public transport prices and offer that maximises a function of collective well-being (sum of the surplus demand, operator profits and the monetisation of environmental impacts), while respecting a subsidy limit for the operation of public transport.


Fabien Leurent
Professor and Research Director
École des Ponts ParisTech
Liu Liu
Postdoctoral Research Fellow
École des Ponts ParisTech
With the growing spread of GPS devices, floating car data can be exploited to explore mobility behaviour at the individual level of the traveller's choices and at the more general level of relationships between places in
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Simulating the daily activities and mobility of people who live in or pass through a neighbourhood makes it possible to better anticipate the economic, social and environmental impacts.
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Practitioner group
Vegetated tramway
Research work on mobility at the neighbourhood level focuses on the development of environmental impact assessment methods that make it possible to better plan the offer of mobility services in the broad sense
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Tramway is among transport services that are analysed
The environmental performance of mobility systems is linked to energy consumption, emissions of pollutants and greenhouse gases and the effects of disruption and fragmentation of natural habitats due to the construction
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