Highlights Demand responsivefreightdeliveriesareoptimizedwithTSPtourlengthapproximations. Headwaysandzoneareasforflexible‐routedeliverysystemsarejointlyoptimizedandclosed‐formsolutionsareobtained. TheproblemisreformulatedasaLagrangianrelaxationproblemtoconstrainanintegerfleetsize. Thesingle‐zonemodelpresentedinthispapercanbethemodularbasisforamulti‐zonemodel withpossiblefreightflowsamongallzones. Thesensitivitiesofresultstoimportantinputfactorsareanalyzed.
Abstract Freight delivery planning is a critical area in transportation and logistics. This paper presents a planning-level model for jointly optimizing headways and zone sizes for flexible-route freight deliveries. The model analyzes deliveries for a one-to-many demand pattern from one terminal to random destinations in a zone, which are reached through approximated travelling salesman problem (TSP) tours. Then, the problem is reformulated as a Lagrangian relaxation problem to constrain the fleet size to an integer value. The proposed model and closed-form solutions provide direct insights into the relations affecting those decision variables. Results from the base case study and sensitivity analyses indicate how various factors affect optimal service frequencies, delivery zone sizes, and costs of freight deliveries. Before detailed vehicle routing problems (i.e., actual delivery scheduling and operations) are solved, the proposed model should be useful for planning freight delivery systems, regarding critical decisions about geographic coverage of services, delivery frequencies, vehicle capacities, and other system characteristics. The developed model can also be used for pickups with a many-to-one demand pattern and extended to serve many-to-many demand patterns in multiple delivery zones through transfers at a central terminal.
Optimal service zones and frequencies for flexible-route freight deliveries
Transportation Research Part A: Policy and Practice ; 159 ; 182-199
2022-03-20
18 pages
Article (Journal)
Electronic Resource
English
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