Abstract
Synchronisation in vehicle routing is a rather new field of research and naturally new problems arise. One of these problems is the Line-haul Feeder Vehicle Routing Problem (LFVRP). It uses a fleet of small and large vehicles to serve two types of customers. The first type provides additional parking space and can be visited by both vehicle classes. The second type can only be visited by the small vehicle class as these customers provide only limited parking space. The main characteristic of the small vehicle class is the limited capacity. To overcome this particular disadvantage, the small vehicles can use the large vehicles as virtual depots. In other words, a small and large vehicle can meet at a parking lot or at a customer with enough space (type-1 customer) and perform a transfer of goods. For a successful reloading operation, both vehicles must be present at the same place at the same time. Thus, both vehicle tours must be synchronized. After using the large vehicle as virtual depot, the small vehicle can proceed immediately afterwards because it does not need to go back to the physical depot. Consequently, less time and distance is required which results in a reduction of the overall costs. The advantage of the LFVRP over classical variants of the Vehicle Routing Problem has been shown in previous papers. Yet, customer time windows have been neglected so far and as time windows play an important role in vehicle routing research, they need to be addressed properly. Therefore, we aim to close this gap by introducing the Line-haul Feeder Vehicle Routing Problem with Time Windows (LFVRPTW). We discuss the complexity of customer time windows for the LFVRPTW and adopt the previously introduced algorithm for the LFVRP. Furthermore, we provide a thorough computational analysis on the impact of different time window characteristics and show the advantage of the LFVRPTW over other variants of the Vehicle Routing Problem with Time Windows.
Highlights
The digital age provides many new possibilities in city logistics and has already changed our way of life.1 Nowadays, customers can look-up a large variety of goods on their mobile device and they can place an order whenever they like
The basic concept of the LFVRPTW algorithm is very similar to the Line-haul Feeder Vehicle Routing Problem (LFVRP) algorithm we proposed in Brandstätter and Reimann (2018a)
We were able to solve all sub-problems of the matheuristic strategy in Brandstätter and Reimann (2018a) in a reasonable amount of time, we realized some difficulties when we applied that principle to the LFVRPTW
Summary
The digital age provides many new possibilities in city logistics and has already changed our way of life. Nowadays, customers can look-up a large variety of goods on their mobile device and they can place an order whenever they like. Due to the vast amount of data, the customer is provided with all the necessary information of a potential purchase; e.g. pictures, number of available items, storage location, overall costs (purchase and delivery) and estimated delivery time These new possibilities increase the expectations of the customers. According to the United Nations (2014), the population of the major European cities will rise to their limits—population will increase up to 20% and more from 2005 to 2020 This will result in multiple issues like higher demands, increased traffic (especially during rush hour), rising land prices, more congested areas with limited space and many more. Compared to the small vehicle class, the large vehicle class has hardly any capacity limit (e.g. a truck with a trailer) They can drive longer distances and have higher overall costs.
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