CHALLENGES AND MODERN SOLUTION IN TRANSPORTATION 121 Stajniak M. et al. (eds.), Challenges and modern solution in transportation, https://doi.org/10.17270/B.M. 978-83-66017-85-6 Katarzyna Gdowska AGH University of Science and Technology e-mail: kgdowska@zarz.agh.edu.pl Roger Książek AGH University of Science and Technology e-mail: rksiazek@zarz.agh.edu.pl Antoni Korcyl AGH University of Science and Technology e-mail: akorcyl@zarz.agh.edu.pl FLEET OPTIMIZATION FOR A SELECTIVE SOLID WASTE COLLECTION SYSTEM ABSTRACT Background: In the paper the vehicle routing problem (VRP) combined with fleet optimization for selected solid waste collection is presented. The fleet of garbage trucks consists of vehicles of various types which can differ one from another with capacity, size, and exclusive assignment to certain types of waste. Garbage trucks are used to collect segregated solid waste from pickup nodes and transport it to specialized sorting units. In real selective solid waste collection systems, an important issue is to route garbage truck subject to not only their size but also the time windows of pickup nodes. Some solid waste drop-off points are located in narrow streets and they can be served only by small-sized or medium-sized garbage trucks. Some pickup nodes can be served only within predefined time windows and visiting them should be scheduled carefully, so that they can be served in the preferred period and garbage trucks’ extra dwell time or extra kilometrage can be avoided. Methods: The Fleet Optimization Problem for Selective Solid Waste Collection (FOPSSWC) continues the approach adopted for the Selective Solid Waste Collection Routing Problem (SSWCRP). The SSWCRP solves the VRP for a predefined heterogeneous fleet of garbage trucks, includes time windows of pickup nodes, and recognizes segregated waste types to be served by dedicated garbage trucks. The FOPSSWC finds the minimum number of garbage