Applications – OR and Management Sciences

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

    Time-of-Use Pump Scheduling for Flow Transmission

  • Yuzhen Feng
    • Categories Energy, Scheduling

    We study time-of-use pump scheduling to deliver a required volume using a finite set of pump combinations with empirical flow–power performance, subject to per-shift caps on pump switches. We prove a structural theorem: partitioning the horizon into maximal intervals with constant tariff and shift (atoms), there always exists an optimal schedule with at most one … 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

    Risk-Averse Stochastic User Equilibrium on Uncertain Transportation Networks

  • Wencheng Bao
  • Chrysafis Vogiatzis
  • Eleftheria Kontou
    • Categories Network Optimization, Robust Optimization, Transportation Tags , , , , ,

    Extreme weather events, like flooding, disrupt urban transportation networks by reducing speeds and capacities, and by closing roadways. These hazards create regime-dependent uncertainty in link performance and travel-time distribution tails, challenging conventional traffic assignment that relies on the expectation of cost or mean excess of cost summation. This study develops a risk- and ambiguity-aware traffic … Read more

    Approximations for Planar Covering Routes: an Analysis and Application to Public School Transportation

  • Dipayan Banerjee
  • Karen Smilowitz
    • Categories Applications - OR and Management Sciences, Production and Logistics, Transportation Tags , , ,

    Public school bus routes can change from year to year as students and their home locations change. However, school administrators benefit from the ability to predict future transportation needs on multi-year time scales. With this motivation in mind, this paper develops planning models for school bus routing when student locations are not known with certainty. … Read more