Network design problems have been studied from the 1950s, as they can be used in a wide range of real-world applications, e.g., design of communication and transportation networks. In classical network design problems, the objective is to minimize the cost of routing the demand flow through a graph. In this paper, we introduce a generalized version of such a problem, where the objective is to tradeoff routing costs and delivery speed; we introduce the concept of speed-coverage, which is defined as the number of unique items that can be sent to destinations in less than 1-day. Speed-coverage is a function of both the network design and the inventory stored at origin nodes, e.g., an item can be delivered in 1-day if it is in-stock at an origin that can reach a destination within 24 hours. Modeling inventory is inherently complex, since inventory coverage is described by an integer function with a large number of points (exponential to the number of origin sites), each one to be evaluated using historical data. To bypass this complexity, we first leverage a parametric optimization approach, which converts the non-linear joint routing and speed-coverage optimization problem into an equivalent mixed-integer linear program. Then, we propose a sampling strategy to avoid evaluating all the points of the speed-coverage function. The proposed method is evaluated on a series of numerical tests with representative scenarios and network sizes. We show that when considering the routing costs and monetary gains resulting from speed-coverage, our approach outperforms the baseline by 8.36% on average.
@InProceedings{rosolia_et_al:OASIcs.ATMOS.2025.9, author = {Rosolia, Ugo and Almagro, Marc Bataillou and Iosifidis, George and Gross, Martin and Paschos, Georgios}, title = {{Speed-Aware Network Design: A Parametric Optimization Approach}}, booktitle = {25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025)}, pages = {9:1--9:16}, series = {Open Access Series in Informatics (OASIcs)}, ISBN = {978-3-95977-404-8}, ISSN = {2190-6807}, year = {2025}, volume = {137}, editor = {Sauer, Jonas and Schmidt, Marie}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2025.9}, URN = {urn:nbn:de:0030-drops-247655}, doi = {10.4230/OASIcs.ATMOS.2025.9}, annote = {Keywords: Network Design, Transportation Networks, Mixed-Integer Programming, Speed-Coverage, Parametric Optimization} }