@MASTERSTHESIS\{IMM2006-04650,
    author       = "I. Kupriyanova",
    title        = "A Vehicle Routing Problem with Time Windows and Shift Time Limits",
    year         = "2006",
    keywords     = "Vehicle routing, time windows, shift time limits, Lagrangian relaxation, set covering, set packing.",
    school       = "Informatics and Mathematical Modelling, Technical University of Denmark, {DTU}",
    address      = "Richard Petersens Plads, Building 321, {DK-}2800 Kgs. Lyngby",
    type         = "",
    note         = "Supervised by Jesper Larsen, {IMM}.",
    url          = "http://www2.compute.dtu.dk/pubdb/pubs/4650-full.html",
    abstract     = "In this thesis a vehicle routing problem with time windows and shift time limits is investigated. An additional specific feature of the problem is a non homogeneous  fleet with a limited number of vehicles of each type.

A two-phase solution method is developed and implemented. The first phase deals with construction of a large set of good quality routes. In the second phase a Lagrangian heuristic is used to solve a mixed set covering/packing problem where columns of the constraint matrix correspond to the routes generated in the first phase.

The developed solution approach is tested on a number of problems of different size. The computational results show that optimal solutions can be found for the set covering/packing problems of small size, i.e. 120 rows and up to 500 columns. As the problem size increases the performance of the Lagrangian heuristic becomes worse."
}