These notes are a series of introductory notes on topics that fall under the broad heading of the field of operations research (OR). They are written by J E Beasley and used as course notes in an introductory OR course at Imperial College.
The vehicle routing problem can be defined as the problem of designing routes for delivery vehicles and is considered to be a challenging optimization task, as an optimal solution does not exist. Hence, the problem consists in designing routes for the vehicles with the objective of minimising a variable such as the total distance travelled.
This is a very useful and interesting website about Vehicle Routing. It has been made in collaboration between AUREN and the Languages and Computation Sciences department of the University of Malaga by Bernabe Dorronsoro Diaz. It provides lot of information concerning the Vehicle Routing Problem, as well as an informed bibliography with the best-so-far solutions of some well-known instances of the problem.
The customers and depot data generated using Solomon's 100 customers VRPTW benchmark instances. More specifically, each customer's demand coupled with a particular commodity, while the total number of customers along with their coordinates, demand, service time and time window intervals maintainted intact. Below the data sets with two and three different commodities are given. The .zip files contain classes R1(4), RC1(4), R2(4), RC2(4). The structure of these files is the following: the first column refers to the customer indetification No, the second and third columns refer to x and y coordinates, the forth and fifth columns refer to the demand along with the respective commodity, and finally the rest columns provide the earliest, latest and service times, respectively. Note that the customer with identification No 0 represents the depot.
The vehicle fleet data was generated using Liu and Shen Fleet Size and Mix VRPTW benchmark instances. To define vehicle capacities and fixed costs Liu and Shen (1999b) proposed three different subclasses of instances a, b and c, each characterized by different fixed vehicle costs. The VFC.zip file provided below contains the fixed costs of the vehicles for subclass a, while A, B, C, D, E, F refer to the vehicle types. Moreover, for each the number of compartments along their associated capacities are given.
In order to define the available fleet composition and mix of vehicles, the best fleet mix obtained in  is assumed to be the given fixed fleet. The latter approach followed also by  and  for solving the Heterogeneous Fixed Fleet VRP. The fixed fleet used is given below for each respective problem instance. Below, the VFFC.zip contains for each respective problem instance the given fleet composition (Fixed Fleet).
 Solomon, M.M. (1987). Algorithms for the vehicle routing and scheduling with time windows contraints, Operations Research 35, 254-265.
 Liu, F.H. and S.Y. Shen (1999b). The Fleet Size and Mix Routing Problem with Time Windows, Journal of the Operational Research Society 50(7), 721-732.
 Tarantilis, C.D., Kiranoudis, C.T., Vassiliadis, V.S. (2004) A threshold accepting metaheuristic for the heterogeneous fixed fleet vehicle routing problem. European Journal of Operations Research, 148-158.
 Taillard, E.D.,(1999) A heuristic column generation method for the heterogeneous fleet VRP. RAIRO 1-14.