Transportation

Stochastic Bilevel Optimization for the Network Design of Multimodal Transit Systems with Heterogeneous Rider Preferences under Uncertain Travel Times and Demand

  • Yiling Zhang
  • Beste Basciftci
    • Categories Bilevel Optimization, Stochastic Programming, Transportation

    Designing efficient and user-friendly multimodal transit networks is critical for modern urban mobility. We study a novel stochastic multimodal transit network design problem that integrates fixed-route services with on-demand shuttles, explicitly accounting for heterogeneous rider preferences, uncertain travel times, and passenger demand. The hierarchical decision-making process is modeled using a two-stage stochastic bilevel optimization problem, … Read more

    Nested Benders Decomposition for Large-Scale Multi-Follower Bilevel Optimization

  • Dominic C. Flocco
  • Philine Schiewe
  • Steven A. Gabriel
    • Categories Bilevel Optimization, Parallel Algorithms, Transportation Tags , , , ,

    We propose a scalable nested Benders decomposition (BD) framework for single-leader, multi-follower bilevel optimization problems. The proposed framework is applicable to bilevel optimization problems in which each follower solves a linear program and is particularly well suited for instances involving a large number of followers. By identifying the upper-level decisions as complicating variables, the method … Read more

    Objective Domain Reduction for Enhancing Solver Performance on Challenging Integer Programs

  • Aadya Bhattarai
  • Lagnajita Basu
  • Tapas Das
  • Kimia Keshanian
  • Hadi Charkhgard
    • Categories Combinatorial Optimization, Integer Programming, Transportation Tags , , , ,

    In this study, we explore how the domain of objective function values for challenging integer programs can be reduced and whether such a reduction can improve the solution process. Our work is motivated by binary search, a technique that efficiently narrows a search space by repeatedly halving it through feasibility checks. Building on this idea, … Read more

    The Distributionally Robust Cyclic Inventory Routing Problem

  • Menglei Jia
  • Albert H. Schrotenboer
  • Ahmadreza Marandi
  • Feng Chen
    • Categories Production and Logistics, Supply Chain Management, Transportation Tags , , ,

    We study the cyclic inventory routing problem that involves joint decisions on vehicle routing and inventory replenishment on an infinite, cyclic horizon. It considers a single warehouse and a set of geographically dispersed retailers. We model retailer demand as random variables with uncertain distributions belonging to a moment-based ambiguity set. We develop a distributionally robust … Read more

    Finite-Sample Optimality and Constraint Satisfaction: Learning-Based Optimal Control in Dynamic Dispatch Networks

  • Moustafa Rashidy
    • Categories Data Science Theory, Production and Logistics, Transportation Tags , ,

    Dynamic dispatch networks in logistics and transportation require real-time, constraint-aware decision-making under stochastic demand. This paper bridges mathematical optimization, optimal control theory, and reinforcement learning by establishing non-asymptotic theoretical guarantees for learning-based optimal control in constrained stochastic dispatch systems. We formulate the problem as a constrained Markov decision process, enforce feasibility via a projection-based policy … Read more

    On vehicle routing problems with stochastic demands — Scenario-optimal recourse policies

  • Matheus Jun Ota
  • Ricardo Fukasawa
    • Categories Branch and Cut Algorithms, Stochastic Programming, Transportation Tags , ,

    Two-Stage Vehicle Routing Problems with Stochastic Demands (VRPSDs) form a class of stochastic combinatorial optimization problems where routes are planned in advance, demands are revealed upon vehicle arrival, and recourse actions are triggered whenever capacity is exceeded. Following recent works, we consider VRPSDs where demands are given by an empirical probability distribution of scenarios. Existing … Read more

    A Newsvendor Model for Last-Mile Fleet Sizing

  • Benjamin Rojas
  • Homero Larrain
  • Mathias A. Klapp
  • Dipayan Banerjee
    • Categories Applications - OR and Management Sciences, Production and Logistics, Transportation Tags , , ,

    We study the tactical problem of determining a last-mile delivery fleet size while accounting for day-to-day uncertainty in the number and location of customer requests. An optimally sized fleet must balance the cost of contracting vehicles against the penalty costs of unserved customers: a larger fleet reduces the risk of unserved demand, but a smaller … Read more

    Finding Minimal Discretizations in Dynamic Discretization Discovery for Continuous-Time Service Network Design

  • Tom Wüllner
  • Alexander Helber
    • Categories Combinatorial Optimization, Network Optimization, Transportation Tags , , ,

    The dynamic discretization discovery framework is a powerful tool for solving network design problems with a temporal component by iteratively refining a time-discretized model. Existing approaches refine the time discretization in ways that guarantee eventual termination. However, refinement choices are not unique, and better choices can yield smaller and easier-to-solve time-discretized models. We pose the … Read more

    Fair Vehicle Routing via Bilevel Optimization

  • Ivana Ljubić
  • Justo Puerto
  • Alberto Torrejon
    • Categories Bilevel Optimization, Transportation Tags , ,

    We propose a novel approach to modeling fairness in the Vehicle Routing Problem (VRP) by introducing objective functions based on ordering route lengths, capturing both monotonic and non-monotonic equity measures. Our method ensures allocations that are efficient, capacity-feasible, and equitable according to criteria like min-max, range, Gini, variance, or absolute deviations. To prevent biased or … Read more