Motorway Interchange Location Model (Three Minutes Presentation)
Optimum Location of Motorway
PhD student Hugo Repolho
University of Coimbra
OBJECTIVE: develop an optimization model for assisting toll-motorway concessionaires in
the analysis of the most profitable solutions for Motorway Interchanges Location Problem.
The location of the interchanges strongly impacts the amount of traffic that the motorway
can capture from the existing road network.
In Europe most motorways are owned by the State but operated by private concessionaires.
The concessionaires may define certain design details for the motorway, namely the
motorway interchanges location (access and exit points).
Their profit comes from the application of a certain toll fee per mile to the motorway users.
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There are two types of routes to consider:
1. Routes through the existing road network (choice 1);
2. Routes through a combination of existing roadway segments and new motorway
segments (choice 2).
• People will travel through the least cost route;
• The proportion of people using the motorway increases as the travel costs decrease;
Choice 1Choice 2
MILM: model’s objective function
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OBJECTIVE FUNCTION: expresses the profit for the concessionaire, given as the
difference between total toll fee revenue and fixed charges for installing and operating
the interchanges and constructing the motorway.
Total toll fee revenue Fixed charges
The MILM can be seen as a particular case of the p-hub median problem, which was
formulated by Campbell, 1994.
Portuguese case study
•Motorway A25 located in the center of Portugal
•Dataset : 55 centers and 33 candidate motorway interchanges;
ArcMap 9.2 Image
The optimum location of motorway interchanges under the concessionaires’
perspective follows a previous work done under the users’ perspective, which
aimed to minimize travel costs.
We believe that the concessionaires’ perspective is the most relevant in real-
The models presented are useful in toll-motorway concessionaires’ cost-benefit