3.57 - Optimal Location of Access Points in Controlled Entry Transportation Networks

Project Description

Decisions regarding the location of access points in national transportation networks need to be made very carefully because of their economic implications. The success of the investments made in transportation networks is highly dependent on the amount of users/passengers captured to the networks, which in turn depends on the location of their access points. This thesis presents a set of strategic decision-making tools (optimization models) addressing the problem of locating access points in controlled entry transportation networks. Two particular types of networks are studied, motorways and railway lines.

The location of controlled access points with modeling of demand based upon the level of provided service versus other competitive modes is central to the work developed in this thesis. The models proposed choose the optimal subset of access points, within a set of possible locations defined a priori, according to a certain objective defined in each case (e.g. minimize travel costs, maximize profits, maximize travel cost savings, maximize social net benefits). In general, the models are based in hub location theory.

Road users and potential rail passengers select their itineraries and transportation mode according to the routes' attractiveness, which is measured by travel costs. Regarding motorways, the choice is between existing road network and a combination of existing road segments with new motorway segments, while for railway lines, the choice is between the new rail service and the existing transportation network.

Regarding the motorways, the interchanges location planning problem is analyzed from the perspective of the various stakeholders, namely road users and concessionaires. The risks and uncertainties involved in motorway investment decisions are also considered through the formulation of stochastic models.

In rail services, special attention is given to the sensitivity of rail ridership to time losses due to stops at intermediate stations. Given the complexity of railway transportation planning the analysis goes beyond strategic issues. Indeed, the author formulates a mixed-integer optimization model that integrates simultaneously all strategic issues related to infra-structure and the subsequent sub-problems (rolling stock management, line planning and train scheduling) that may influence optimal investment decisions at a strategic level.

The author is also concerned with the applicability of the models developed. More than academic modeling, the study aims the characterization of real-world problems and the development of formulations capable of providing optimal solutions. With this in mind, the models are tested on two academic examples based on real-world networks: an important Portuguese motorway, the A25; and a high-speed rail line expected to be built in Portugal in the near future (Lisbon-Porto high line). The solutions provided by the models are compared with the ones already implemented in reality (the case of the A25 motorway) or the ones planned to be implemented (the case of the Lisbon-Porto line).

Research Team


  • Hugo Repolho
  • António Pais Antunes (supervisor)

University of California, Santa Barbara

  • Richard Church
Financial Support
  • University of Coimbra
Stage of Progress
  • Concluded in 2011