An Caris

Hasselt University · Logistics Research Group (LOG)

Pre- and end-haulage of intermodal container terminals involves the pickup or delivery of containers at customer locations. The drayage of containers in the service area of an intermodal terminal has been modelled as a full truckload pickup and delivery problem with time windows (FTPDPTW). The research investigates two concepts, borrowed from...

Market trends such as globalisation, increasing customer expectations, expensive industrial land and high labour costs cause a need for efficient order picking systems in practice. However, managers often do not implement findings from academic research on order picking planning into practice because researchers hardly account for practical factors...

In a business-to-consumer (B2C) context, customers order more frequently and in smaller quantities, resulting in a high number of consignments. Moreover, online shoppers expect a fast and accurate delivery at low cost or even free. To survive in such a market, companies can no longer optimise individual supply chain processes, but need to integrate...

Functions in supply chain management are interrelated. This means that optimization of the decisions in these functions can benefit from integration of the decision problems. The most well-known integration is the combination of production scheduling and vehicle routing. As e-commerce is growing fast, the function, which proceeds vehicle routing, i...

A vehicle routing problem (VRP), using a mixed fleet of vehicles, with sequence-based pallet loading and axle weight constraints is introduced. The effect of the integration of axle weight constraints in a Fleet Size and Mix VRP is analyzed by comparing the problem with and without axle weight constraints. A vehicle fleet of 30-foot and 45-foot tru...

Long-haul continental freight flows still heavily rely on unimodal road transport. Intermodal transport, combining road transport with other transport modes, has the potential to have lower operating costs and to be more environmentally sustainable. However, road transport benefits from its better flexibility and adaptability to sudden disruptions...

An intensified competition forces warehouses to handle more orders in shorter time windows. This complicates the timely retrieval of these customer orders. Planning order picking operations, thereby aiming to increase efficiency, inevitably results in balancing concerns, such as imbalances among pick areas, pickers or time periods. Reducing workloa...

A vehicle routing problem (VRP) with sequence-based pallet loading and axle weight constraints is introduced in the study. An Iterated Local Search (ILS) metaheuristic algorithm is used to solve the problem. Like any metaheuristic, a number of parameters need to be set before running the experiments. Parameter tuning is important because the value...

Warehouses play a vital role in every supply chain. The focus of warehouses is often on organising efficient and flexible order picking systems. However, warehouse managers indicate that planning order picking operations becomes extra complicated as they have to comply to many legislations. Warehouses in Europe are subject to the classification, la...

A growing e-commerce market and increasing customer requirements put extra pressure on order picking operations. Collecting large quantities of relative small orders within limited time windows makes workload balancing in order picking a challenging and complicated task. Therefore, warehouse managers experience difficulties in balancing the daily w...

The Physical Internet (PI) concept presents a radical change with the aim to revert the unsustainable practices that are used for transporting goods. It identifies dedicated freight flows and transforms them into transparent open logistics networks which can be accessed by other users, such as shippers and carriers. In this paper, we test the unive...

Market trends such as globalisation, increasing customer expectations, expensive industrial land and high labour costs cause a need for efficient order picking systems in practice. However, managers often do not implement findings from academic research on order picking planning into practice because researchers hardly account for practical factors...

When developing optimisation algorithms, the focus often lies on obtaining an algorithm that is able to outperform other existing algorithms for some performance measure. It is not common practice to question the reasons for possible performance differences observed. These types of questions relate to evaluating the impact of the various heuristic...

Knowing the availability of human resources for a business process is required, e.g., when allocating resources to work items, or when analyzing the process using a simulation model. In this respect, it should be taken into account that staff members are not permanently available and that they can be involved in multiple processes within the compan...

Transparency and information exchange are important parts of synchromodality that contribute to better overview of options when tackling delays, dynamic switching, and handling of unexpected events that affect delivery lead-times and costs. The most challenging aspect when making decisions in a complex adaptive dynamic system, is the ever-changing...

In order to survive under the ever increasing pressure to operate more efficiently, transportation companies are obliged to adopt a collaborative focus. Although organisations become increasingly aware of the inevitable character of horizontal collaboration, surveys report failure rates up to 70% for starting strategic partnerships. While a growing...

This study illustrates the relevance and importance of incorporating safety constraints, picker blocking, and vertical travel due to high level storage locations when developing order picking systems (i.e., deciding on zoning, storage, batching, and routing). Results show that safety constraints induce wait times, and cause additional traveling, pi...

Batch processing refers to an organization of work in which cases are synchronized such that they can be processed as a group. Prior research has studied batch processing mainly from a deductive angle, trying to identify optimal rules for composing batches. As a consequence, we lack methodological support to investigate according to which rules hum...

To achieve socioeconomic and environmental sustainability, utilization of existing capacities and assets has become a key challenge for the transportation sector. This challenge has been recognised by many scholars, policy makers and practitioners leading to a substantial body of new concepts and models. The rather parallel evolution of the Physica...

Synchromodal transport incorporates real-time events in a dynamic manner in order to facilitate the most suitable selection of modes, routes and handling points. Up until now, current assessments rely on analytical models. Most of these models average distances for barges and trains via route mapping platforms that provide realistic distances for r...

Intermodal logistics service providers decide on the routing of demand through their service network. Long-haul routing decisions determine the selected departure and arrival terminals for containers and imply corresponding drayage tasks. Traditionally, given these long-haul routes and fixed drayage tasks, drayage operations are planned in a second...

New market developments increase the complexity of managing order picking operations. Integrating order picking planning problems enables warehouse managers to organize order picking operations more efficiently. This paper provides a decision support tool that integrates and solves the three main operational order picking planning problems (i.e., o...

The field of combinatorial optimization has inspired the development of a large number of heuristic solution procedures. These methods are commonly assessed using a competitive evaluation methodology that may give an indication of which algorithm has a better performance. A next step in the experimental analysis is to uncover “why” one algorithm pe...

In B2C e-commerce sales, customers expect a fast and low-cost delivery. To be able to fulfil these customer expectations, both warehouse and distribution operations have to be performed in an efficient and effective way. Ideally, these two supply chain functions should be considered simultaneously in an integrated problem since they are interrelate...

Heuristic algorithms are most commonly applied in a competitive context in which the algorithm is tested on well-known benchmarks of some problem application with the objective of obtaining better performance results than the state-of-the-art. Focusing on characterising heuristic algorithm behaviour to acquire insight and knowledge of how these sol...

E-commerce sales are increasing every year and customers who buy goods on the Internet have high service level expectations. In order to meet these expectations, a company’s logistics operations need to be performed carefully. Optimizing only internal warehouse processes will often lead to suboptimal solutions. The interrelationship between the ord...

When a company wants to use business process simulation to support decision-making, a simulation study needs to be conducted. Using a clear stepwise method can avoid overlooking key activities during the simulation study and improves the study’s credibility towards decision-makers or project sponsors. In this tutorial, a method to perform a simulat...

Freight transport planning is nowadays encouraged to align with environmental objectives. Among those, climate change is of particular interest for many countries. In its White Paper on Transport, the European Commission considers intermodal transport as a potential solution for reducing environmental impacts. In order to make good strategic transp...

Departing from the universal network openness, the users can tap into the PI network and place orders which will be assigned to the nearest available transport service and consequently delivered to the order sender. The objective of our paper is to investigate the impact of stochastic insertion of service points into existing dedicated freight flow...

Purpose: Synchromodal transport incorporates real-time events in a dynamic manner in order to facilitate the most suitable selection of modes, routes and handling points. Up until now, current modeling approaches that focus on the dynamic context of synchromodal transport make use of analytical models. Most of these models average distances for ba...

Logistics service providers become increasingly aware of the need to collaborate to face challenges such as globalization and the heightened expectations of customers. This paper focuses on horizontal cooperation between logistics service providers in road transportation and introduces two novel conceptual models. Firstly, a decision framework for...

European e-commerce sales are increasing every year. Nowadays, customers buy more frequently online in smallerquantities. Handling this large amount of customer orders puts the logistic activities of the supply chain underpressure. At the same time, customers have high expectations concerning the delivery of their online purchase. Inorder to meet t...

Warehouses deliver labor-intensive services to customers. Underperformance may result in high costs and unsatisfied customer demand. New market developments force warehouses to handle a large number of orders within tight time windows. To cope with this, order picking operations need to be optimized by solving a wide range of planning problems. Opt...

In order to differentiate from competitors in terms of customer service, warehouses accept late orders while providing delivery in a quick and timely way. This trend leads to a reduced time to pick an order. The main objectives of this research are to determine which order picking planning problems are related, to explain why and how individual pla...

In intermodal freight transportation, train load planners are confronted with complex practical considerations during the booking and planning process. In order to optimally utilize the available loading space, train capacity is monitored in terms of available length and weight while accounting for the urgency with which load units must be sent. Fu...

Dial-a-ride problems consist of designing vehicle routes and time schedules in a system of demand-dependent, collective people transportation. In the standard problem, operational costs are minimized, subject to full demand satisfaction and service level requirements. However, to enhance the practical applicability of solution methods, authors incr...

In order to improve the competitive position and efficiency level of multimodal transport, consolidation of freight flows is often suggested. Bundling networks require cooperation between multiple partners in the multimodal transport chain. In this context, the question rises how benefits may be allocated fairly among the spatially distributed partic...

In order to differentiate from competitors in terms of customer service, warehouses accept late orders while providing delivery in a quick and timely way. This trend leads to a reduced time to pick an order. This paper introduces workload forecasting in a warehouse context, in particular a zone picking warehouse. Improved workforce planning can con...

Dial-a-ride services provide collective on-demand transportation, usually tailored to the needs of people with reduced mobility. This paper investigates the operational effects of horizontal cooperation among dial-a-ride providers. The current practice is that users choose a particular provider to submit their requests. Providers operating in the s...

A dial-a-ride system is an application of demand-dependent, collective people transportation. Users request a trip between an origin and destination of choice. A time window is imposed on the departure or the arrival of the user and his ride time (the time spent in the vehicle) is limited. The service provider attempts to develop efficient vehicle...

To achieve socioeconomic and environmental sustainability, utilization of existing capacities and assets has become a key challenge for the transportation sector. New concepts such as the Physical Internet and synchromodality offer an alternative to the current " business as usual " setting of freight transport services. In this paper, we thus star...

Intermodality, as well as the more recent concept of synchromodality, provide a promising opportunity for shifting to more environmental friendly transport modes. One key aspect of synchromodality concerns real-time switching, such that most assignment decisions are proactive and more responsive to internal and external perturbations compared to a...

In this paper, the Fleet Size and Mix Vehicle Routing Problem (FSM) with sequence-based pallet loading and axle weight constraints is introduced. The effect of the integration of axle weight constraints in a FSM is analyzed by comparing the FSM with and without axle weight constraints. A vehicle fleet of 30-foot and 45-foot trucks, consisting of a...

The dial-a-ride problem consists of designing a number of minimum-cost vehicle routes in a system of demand-dependent, collective people transportation. Quality is ensured by taking into account service level requirements. However, little research has been performed regarding the effect of simultaneous service level variations on operational costs...

Resources can organise their work in batches, i.e. perform activities on multiple cases simultaneously, concurrently or intentionally defer activity execution to handle multiple cases (quasi-) sequentially. As batching behaviour influences process performance, efforts to gain insight on this matter are valuable. In this respect, this paper uses eve...

Production scheduling and vehicle routing are two well-studied problems in literature. Although these supply chain functions are interrelated, they are often solved sequentially. This uncoordinated approach can lead to suboptimal solutions. In the current competitive business environment, companies are searching for methods to save costs and improv...

The transportation of goods is essential for the economy, but it also contributes to air pollution which, in turn, affects human health. These negative impacts generate additional costs for society that are not necessarily taken into account in public transportation policies and in private transportation decisions of companies and individuals. This...

Process mining mainly focuses on the retrieval of process models from event logs. As these discovery algorithms make assumptions, performance analyses based on these models can present a biased view. In literature, algorithm-agnostic process metrics have been introduced. Given the critical importance of resources in the light of continuous process...

Transport companies may cooperate to increase their efficiency levels by e.g. the exchange of orders or vehicle capacity. In this paper a new approach to horizontal carrier collaboration is presented: the sharing of distribution centres (DCs) with partnering organisations. This problem can be classified as a cooperative facility location problem an...

In order to differentiate from competitors in terms of customer service, warehouses accept late orders while providing delivery in a quick and timely way. This trend leads to a reduced time to pick an order. The objective of this research is to simulate and evaluate the interaction between several storage, batching, zone picking and routing policie...

In order to improve the competitive position and efficiency level of intermodal transport, consolidation of freight flows is often suggested. Bundling networks require cooperation between multiple partners in the intermodal transport chain. In this context, the question rises how benefits may be allocated fairly among the participants in the cooper...

Resources are a critical component of a business process as they execute the activities. These resources, especially human resources, are not permanently available and tend to be involved in multiple processes. However, a company might wish to analyze or model a single process. To this end, insights need to be gathered on the availability of a reso...

Train load planners are confronted with complex practical considerations during the booking and planning process. In order to optimally utilize the available loading space, train capacity is monitored in terms of available length and weight while accounting for the urgency with which load units must be sent. Furthermore, the execution of the load p...

A dial-a-ride system is an application of demand-dependent, collective people transportation. Users request a trip between an origin and a destination of choice, to which service level requirements are linked. The service provider attempts to develop e fficient vehicle routes and time schedules, respecting these requirements and the technical const...

This paper considers a generalization of a bi-objective dial-a-ride problem, incorporating real-life characteristics of patient transportation. It studies the impact of combination restrictions, preventing particular user combinations and limiting the set of drivers to which particular users can be assigned. The academic literature currently lacks...

A dial-a-ride system is an application of demand-dependent, collective people transportation. Users request a trip between an origin and a destination of choice, to which service level requirements are linked. The service provider attempts to develop efficient vehicle routes and time schedules, respecting these requirements and the technical constr...

The paper focuses on the use of process mining (PM) to support the construction of business process simulation (BPS) models. Given the useful BPS insights that are available in event logs, further research on this topic is required. To provide a solid basis for future work, this paper presents a structured overview of BPS modeling tasks and how PM...

In this paper, we introduce and study the capacitated vehicle routing problem with sequence-based pallet loading and axle weight constraints. To the best of our knowledge, it is the first time that axle weight restrictions are incorporated in a vehicle routing model. The aim of this paper is to demonstrate that incorporating axle weight restriction...

A resource typically executes a particular activity on a series of cases. When a resource performs an activity on several cases simultaneously, (quasi-) sequentially or concurrently, this is referred to as batch processing. Given its influence on process performance, batch processing needs to be taken into account when modeling business processes f...

Accurately modeling the interarrival times (IAT) is important when constructing a business process simulation model given its influence on process performance metrics such as the average flow time. To this end, the use of real data from information systems is highly relevant as it becomes more readily available. This paper considers event logs, a p...

Operational planning decisions of a carrier consist of accepting transport requests and constructing vehicle routes. However, a carrier has only a limited capacity within his own vehicle fleet and can only serve a selection of clients. Transport requests are accepted only if they contribute to a higher total profit. This practical aspect is modelle...

The train load planning problem involves the assignment of outbound load units to a location on a train. Optimization of this planning task can support train planners in their decision-making process by making cost-efficient and time-saving decisions. In this paper interesting research directions are identified from current literature on train load...

As customer markets globalize, supply chains are increasingly depending on efficient and effective logistic systems in order to distribute products in a large geographical area. Warehouses are an important part of supply chains, and therefore warehouse operations need to work in an efficient and effective way. Currently, literature mainly focusses...

A pickup and delivery problem is a special case of the vehicle routing problem in which goods at customer sites are either picked up or delivered. A carrier has only a limited capacity within his own vehicle fleet. Therefore the carrier can only serve a selection of customers. Transport requests of clients are accepted only if they contribute to a...

The construction of a business process simulation (BPS) model requires significant modeling efforts. This paper focuses on modeling the interarrival time (IAT) of entities, i.e. the time between the arrival of consecutive entities. Accurately modeling entity arrival is crucial as it influences process performance metrics such as the average waiting...

In order to differentiate from competitors in terms of customer service, warehouses accept late orders from customers, while providing delivery in a quick and timely way. This leads to a reduced time to pick an order. In this study, the order picking process in a warehouse is discussed. In order to reduce the order picker travel time per order, the...

A dial-a-ride system is an application of demand-responsive, collective people transportation. Each user requests a trip between an origin and a destination of choice, to which a number of service level requirements are linked. The service provider attempts to develop efficient routing schedules, respecting these service level requirements and the...

This paper presents an algorithm for the vehicle routing problem with soft time windows (VRPSTW). It involves serving a set of customers, with earliest and latest time deadlines, which may be violated if a penalty is paid, and a constant service time at the customer site. Customer demands are served by capacitated vehicles. The purpose of this rese...

Single-objective solution methods for the dial-a-ride problem usually minimize operational costs while ensuring a minimum quality level imposed by service level requirements. This solution technique emphasizes the fundamental nature of the problem by solving a bi-objective variant. Total user ride time, being the total time users spend aboard the v...

The operational planning decisions of a carrier consist of accepting transport requests of customers and constructing daily vehicle routes. Several customers may have less-than-truckload requests to be transported between two specified locations: these customers are consolidated into vehicle tours by the carrier. However, a carrier has only a limit...

A dial-a-ride system is an application of demand-dependent, collective people transportation. Each user requests a trip between an origin and a destination of choice, to which a number of service level requirements are linked. The service provider attempts to develop efficient routing schedules, respecting these requirements and the technical const...

As warehouses operate in a competitive environment, this research plan discusses the order picking process in a warehouse. In order to reduce the order picker travel time per order, orders can be batched and the warehouse can be divided into different zones. Furthermore an improved workforce planning can contribute to an effective and effcient orde...

This paper presents an Iterated Local Search (ILS) for the CVRP with sequence based pallet loading and axle weight restrictions with and without dense packing. The problem deals with the distribution of pallets to different locations while taking into account that items may not be shifted during the trip and that axle weight limits need to be respe...

Production and distribution have traditionally been studied as two independent problems. In reality these supply chain processes highly interact and combined decision support models are therefore needed. Production and distribution can be integrated at different decision levels. At the tactical level, the interdependence between production lot-sizi...

Distributors are faced with loading constraints in their route planning, e.g.,multi-dimensional packing constraints, unloading sequence constraints, stability constraints and axle weight limits. Ignoring these constraints impairs planning and induces last-minute changes resulting in additional costs. Developing vehicle routing models incorporating...

This paper focuses on the potential of process mining to support the construction of business process simulation (BPS) models. To date, research efforts are scarce and have a rather conceptual nature. Moreover, publications fail to explicit the complex internal structure of a simulation model. The current paper outlines the general structure of a B...