Rail traffic should grow significantly in the coming years. For example, passenger demand is expected to be quadrupled by the year 2030. The same logic applies to freight transport since the environmental guidelines of French government include the transfer of 500 000 trucks every year from road to rail. However this evolution won't really occur without users acceptance of the service provided by rail transport.
To fulfill the future demand for transport, the French national railway company (SNCF) must therefore ensure a stable and reliable transport plan which requires anticipating the needed investments (infrastructure and equipment) and to use adequately available resources. The SCRIPT project thus addresses the following issues:
- Social issue, through the improvement of the quality of service (regularity / punctuality).
- Economic issue, by searching a compromise between cost and stability of the transport plan, and by keeping under control the costs which result from the operational management of delays.
- And indirectly, environmental issue, since quality of service is indeed an important incentive to promote the modal shift from road to railway.
The SCRIPT project focuses on the design of robust railway transport plans. It aims to define indicators which model the stability of a plan by considering all of the critical resources needed (track, rolling-stock, crew), and then to propose methods that build optimised stable plans and validate them on real data with a simulator.
Thus, the main objectives of the project are:
- To build a shared and practical vision of the consequences of disturbances, as well as the available ways to deal with them at the design step, by defining reliable indicators.
- To propose innovative methods for the design and optimisation of railway transport plans under uncertainties.
- To study their applicability and their impact on the planning of rolling-stock and crew.
Optimisation of stability indicators and experimental validation of their impact on plans
The first step of the project has been to make a state of the art of the various indicators and methods proposed in literature to assess stability in the railway field and in nearby areas, but also to identify the interactions between different critical rail resources through integrated planning. Combined with this work, various discussions with SNCF planners have permitted to build a common view among all the partners involved in the project.
The first main results of the project correspond to a railway transport plan simulator and its validation with some experiments on real-life data. Combined with a model of users' behaviour and sight, this simulator should provide both:
- an original tool to assess the consequences of various disturbances of railway transport plans,
- a better understanding of the various indicators or metrics which can measure theses consequences.
A further research perspective concern the development of optimisation methods dealing efficiently with the planning of various ressources to produce robust railway transport plans.
The simulation model and the results of the first experiements performed on real-life data have been presented during a conference (A. Zehrouni, F. Grimaud, O. Guyon, X. Delorme, D. Feillet. Évaluation de la robustesse des plans de transport ferroviaires par simulation. 15th congress of the French national society of operations research and decision science (ROADEF 2014), Bordeaux, France, February 2014, In French).