Johan W. Joubert

• PhD
• Professor at KU Leuven

A country’s maritime connectivity is integral to its international trade and regional economic growth. Advancements in technology and complex network theory have elevated maritime connectivity in regional transport policy agendas. This study introduces a novel conceptualisation of the maritime network called the market proximal network which better...

This study aimed to describe the disposable diaper usage, disposal practices and quantity estimation in a specified rural setting within a developing, sub-Saharan country, South Africa. Quantitative and qualitative data collection methods were used to collect primary data, which included survey research, focus group discussions, participatory thema...

This work presents a comparative study of the performance of different meta-heuristic algorithms used within a simulation-based optimisation model that is used to design public transit networks. Simulation-based optimisation focuses on solving decision-based problems by integrating optimisation and simulation. The model combines multi-objective met...

Many cities plan to grow cycling as a prominent mode to improve accessibility and environmental and financial sustainability. However, relatively few cities have made meaningful headway in this direction. Policymakers would be more inclined to implement the necessary interventions when they have certainty about potential demand, especially knowing...

Public transport systems play a critical role in improving mobility and access to opportunities, which is crucial for the socio-economic growth and well-being of any society. A key component of the system is the actual transit network, which usually consists of interconnected nodes and links that enable people to access the system and to travel to...

Public transport network design deals with finding efficient network solution(s) from a set of alternatives that best satisfies the often-conflicting objectives of stakeholders like passengers and operators. This work presents a simulation-based optimization (SBO) model for designing public transport networks. The work’s novelty is in developing su...

Car dependency in Cape Town, South Africa, like in many modern cities is high but comes at a high cost. One of these is significant network congestion, especially during peak commuting periods. A strategy adopted by the City's transport development authority to alleviate this situation is the phased development of an integrated public transport net...

Conventional wisdom is that a person’s attitude towards an issue dictates their behaviour. In contrast, self-perception theory accounts for how a person forms their attitude. In the context of this paper, the theory asserts that a person can, in the absence of prior experience, establish an attitude towards cycling based on observing their own, hop...

Simulation is a valuable prediction tool to evaluate the impact of climate change interventions prior to disruptive implementations that may yield unintended and unwanted consequences. Advances in agent-based simulation allow us to estimate the dynamic emissions produced by vehicles at a fine resolution, with each vehicle modelled individually. The...

To deal with increasing amounts of data, decision and policymakers frequently turn to advances in machine learning and artificial intelligence to capitalise on the potential reward. But there is also a reluctance to trust black-box models, especially when such models are used to support decisions and policies that affect people directly, like those...

In understanding travel demand, research often relies on global positioning system (GPS) data, which is becoming ubiquitous. The spatiotemporal nature of the GPS data allows for studying the behaviour at rich and detailed levels. Some of the steps in the data processing frequently rely on unsupervised machine learning techniques such as activity cl...

Data generated from telemetry devices, such as acceleration and speed, are used in a variety of industries to determine the risk profile of a driver. This paper considers the addition of road gradient as a contextual variable to a driving behavior model to determine specifically if the risk of a driver is influenced by different road grades. This b...

Logistics sprawl has been observed in many urban areas around the world, but the assumed link between increased logistics sprawl and increased freight transport activity has little empirical evidence. Because this link could influence policy-making to either fight or facilitate logistics sprawl, this paper investigates the implications of using dif...

RDE is becoming a necessary element of the emissions certification of automotive vehicles. Real Driving Emissions (RDE) helps to ensure that the regular operation of a car, or heavy vehicle, is still within the acceptable emissions standards while driving under normal conditions. RDE is monitored by connecting a Portable Emissions Measurement Syste...

This paper proposes an adjusted econometric approach to quantity accessibility. The metric can have significant benefits in allowing to account for inequality in evaluating transport interventions in an agent-based setting. Econometric accessibility, in its traditional form, is a place-based metric allowing us to account for the benefit of particip...

Freight transport stakeholders can benefit from collaborative planning. Unfortunately, appropriate decision and planning support tools are lacking. Consequently, freight stakeholders remain unaware of collaboration opportunities and the potential benefit of those coalitions. This paper focuses on implementing collaboration between urban freight rec...

In the automotive industry, a Body in White (BIW) refers to the first step, the basic structure, in the production of a vehicle. Once a BIW production line has been built, the (maximum) capacity is fixed and throughput is therefore limited by the equipment specified during the design phase. The main metric used to inform the production line design...

Establishing cycling as a prominent utility mode is recognised as central to creating sustainable transport systems in many cities around the world. Strategies of starter cycling cities are often biased to the supply of infrastructure along prominent corridors without acknowledging the nature, quantum or location of potential demand for cycling. De...

Scenarios with high levels of diversity lend themselves to be represented or imitated by disaggregate, agent-based models as the individual agents can capture the unique attributes of the constituents of the overall system. This paper describes the methodology to establish a baseline transport simulation model, using MATSim, to represent and imitat...

Agent-based simulation lends itself to study emergent behaviour when agents respond autonomously, based on their unique and individual attributes, to external interventions. In transport, the vehicle-specific attribute of interest is its fuel efficiency and emissions. While research showed that vehicle-specific emissions can be accounted for in ter...

While activity-based travel demand generation has improved over the last few decades, the behavioural richness and intuitive interpretation remain challenging. This paper argues that it is essential to understand why people travel the way they do and not only be able to predict the overall activity patterns accurately. If one cannot understand the...

Automated driving technology along with electric propulsion are widely expected to fundamentally change our transport systems. They may not only allow a more productive use of travel time, but will likely trigger completely new business models in the mobility market. A key determinant of the future prospects of both existing and new mobility servic...

Paratransit often emerges in the absence of sufficient formal transit. As governments try to catch up and improve the formal transit service offering, their efforts are often undermined by the quick and dynamic response of the paratransit mode. Recent advances in transport modelling, using agent-based simulation, can provide better decision support...

The ubiquity of anonymous GPS data has opened the door to a promising data source in the field of city logistics modelling. From this data the locations of logistics facilities can be extracted and their evolution studied over time. The minimum edge cover problem, weighted by the Hausdorff distance, is used as a basis for a matching algorithm to st...

This paper is concerned with using MATSim to investigate off-hour delivery collaboration between a carrier and receivers agents in the City of Cape Town, South Africa. Results indicate that the carrier’s delivery cost reduced by up to 12.1% when more receivers were willing to accept off-hour deliveries. This reduction was facilitated by the ability...

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translate...

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translate...

In this work, a transit network design problem is presented. The problem is identified as a typical large-scale complex system. Subsequently, it is decomposed into its sub-components. The first two sub-components, which encompass the network design and frequency setting problems, are then tackled by means of an innovative solution framework that co...

The rapid development and proliferation of global positioning system (GPS)-enabled systems and devices have led to a significant increase in the availability of transport data, more specifically GPS trajectories, that can be used in researching vehicle activities. In order to save data storage- and handling costs many vehicle tracking systems only...

This article presents the design and evaluation of transit networks using a route expansion heuristic and agent-based travel demand simulation. The route expansion mechanism is a type of constructive heuristic algorithm that derives new transit routes by inserting neighbouring nodes into existing routes with the aim of improving the demand coverage...

In this paper, we extend our previous work on greedy constructive heuristics for the Mixed Capacitated Arc Routing Problem under Time Restrictions with Intermediate Facilities (MCARPTIF) by developing efficient Local Search improvement heuristics for the problem. Five commonly used arc routing move operators were adapted for the problem, and basic...

An increase in urban freight transport is inevitable as growing urban populations require more goods, more conveniently. A deeper understanding of the geography and trends of urban freight transport must recognise that it is the aggregate result of a complex web of supply chain interactions. To understand the trends, the behaviour of the underlying...

In recent years many authorities have considered heavy vehicle restrictions, or complete bans, in certain parts of the city to alleviate both congestion and other externalities. But such restrictions are often implemented without regard for the true impact, both intended and unintended. One reason is because anticipating the effects, through modell...

Recent advances in large-scale mobility models have shown that much system-level insight can be gained when modelling at the disaggregate, individual level. Although the focus is often on the movement of vehicles and/or individual people, agent-based simulation modelling is used in this paper to model the mobility of bottles on a conveyor line. Mor...

There is a need for collaborative urban freight planning and appropriate decision and planning support tools are lacking, resulting in inadequate understanding of how urban freight agents should collaborate and what benefits can be gained from their coalitions. This paper is therefore concerned with including receiver freight agents as autonomous a...

The fields of behavioural transport modelling has been gaining momentum and many researchers have focused on incorporating some elements of stakeholder behaviour and decision making into their freight planning tools. However, investigation of the literature reveals that few papers are devoted to understanding and integrating logistics behaviour of...

Many authors argue that issues related to interpretability, lack of data availability, and limited applicability in terms of policy analysis have hindered a more widespread use of accessibility indicators. Aiming to address these aspects, this paper presents two accessibility computation approaches applied to Nelson Mandela Bay in South Africa. The...

This chapter evaluates the impact of relocating a container terminal from the harbor area of the City of Cape Town's Central Business District (CBD) to one of the two hinterland locations by using a multi‐agent model. It provides a brief overview of the multi‐agent transport simulation (MATSim) toolkit. The chapter investigates and demonstrates the...

This article presents the procedure followed to generate complete synthetic populations from the South African National Census. The populations are accurate at both household and individual level, and were generated for nine major metropolitan and provincial areas. The disaggregate description of the population is useful in a variety of modelling c...

Making a supply chain more resilient and making it more efficient are often diametrically opposed objectives. Managers have to make informed trade-offs when designing their supply chain networks. There are many methods available to quantify and optimise efficiency. Unfortunately the same cannot be said for vulnerability and resilience. We propose a...

Advances in multi-agent models in the field of vehicular transport are showing much potential for improved decision support. Large scenarios of metropolitan or even national scale can be modelled efficiently and provide rich result sets with more accurate travel time predictions. Some of the efficiency seems to come from using primitive heuristics...

Accurate travel time predictions are required when evaluating transport infrastructure. Travel times, in turn, are influenced by time of day, vehicle type and the density of vehicles, amongst other characteristics. Advances in multi-agent models have shown to predict travel times more accurately, and allow for rich result sets as each vehicle (or p...

Literature agrees that road grade plays a significant role in the energy consumed and the emissions emitted by vehicles. This is even more true for medium and heavy duty vehicles. Unfortunately the vehicle-specific energy and emissions resulting from route choices are all but lost in macroscopic models.

This article presents the multilayered complex network formulation for three different supply chain network archetypes on an urban road grid and describes how 500 instances were randomly generated for each archetype. Both the supply chain network layer and the urban road network layer are directed unweighted networks. The shortest path set is calcu...

Freight vehicle movement can be captured using activity chains, which capture the freight related activities both spatially and temporally. This is an advancement over origin-destination matrices, since freight vehicles are studied at a disaggregate level. Digicore Fleet Management has provided GPS data of over 40,000 freight vehicles travelling in...

Many city logistic initiatives are large in scale and aim to improve the efficiency and overall state of goods movement within our urban areas. Unfortunately the implementation and day-to-day operations of urban goods movement is less than optimal. Commercial vehicles have many activities in their activity chains, from when they start at a terminal...

Telemetry devices are generating and transferring increasingly more data, with notable potential for decision makers. In this paper we consider the accelerometer and speed data produced by in-vehicle data recorders as a proxy for driver behaviour. Instead of extracting harsh events to cope with the large volumes of data, we discretise the data into...

In this article we present benchmark datasets for the Mixed Capacitated Arc Routing Problem under Time restrictions with Intermediate Facilities (MCARPTIF). The problem is a generalisation of the Capacitated Arc Routing Problem (CARP), and closely represents waste collection routing. Four different test sets are presented, each consisting of multip...

Available at: https://data.mendeley.com/datasets/9x4vd92rcj/2 DOI: 10.17632/9x4vd92rcj.2 The dataset contains 5 benchmark test sets for the Mixed Capacitated Arc Routing Problem under Time Restrictions with Intermediate Facilities (MCARPTIF), which is a generalisation of the Capacitated Arc Routing Problem. The problem closely represents waste col...

Using complex network theory to describe the relational geography of maritime networks has provided great insights regarding their hierarchy and evolution over the past two decades. Unlike applications in other transport fields, notably air transport, complex network theory has had limited application in studying the vulnerability of maritime netwo...

This paper develops optimal and quick near-optimal splitting procedures for the Mixed Capacitated Arc Routing Problem under Time restrictions with Intermediate Facilities. Splitting procedures are a key component of giant tour-based solution methods for Arc Routing Problems. The optimal and near-optimal splitting procedures are tested within a mult...

Environmental Diversity (ED) has been proposed as a potential biodiversity surrogate for use in spatial biodiversity planning. The concept is based on the premise that differences in species composition between areas are correlated with differences in environmental conditions. If this is true then sites selected to represent the full range of envir...

The Mixed Capacity Arc Routing Problem under Time Restrictions with Intermediate Facilities (MCARPTIF) is an extension of the Arc Routing Problem under Capacity and Length Restrictions with Intermediate Facilities (CLARPIF) with application in municipal waste collection. This paper evaluates four constructive heuristics capable of computing feasibl...

Mining is a competitive business with many players. The survival of a mine in the business is determined by its efficiency and cost-effectiveness relative to the other producers. Both new and operating mines should select optimal technical variables, such as the production rate, that will make them competitive, taking into account mine-unique proje...

Inventory management under uncertainty is a widely investigated field and many different types of inventory models have been used to address inventory problems in practice. However, a look at the literature reveals that few papers are devoted to inventory planning and management in environments characterised by uncertainty resulting from extreme ev...

Cost estimation for surface coal mines is a critical practice that affects both profitability and competitiveness. New mines require these costs to be estimated using available information before a project begins. The competitive advantage of a new mine depends on it being both efficient and cost-effective. Low-cost producing mines have a higher ch...

We rarely associate social networks with the movement of freight vehicles. Yet, taking a network perspective on supply chains has seen a strong interest in recent literature. It allows for a variety of system-level analysis that is not possible when taking a single focal firm view as is often the case in more classical supply chain approaches. Crea...

As transport modellers we are interested in capturing the behaviour of freight vehicles that includes the locations at which vehicles perform their activities, the duration of activities, how often these locations are visited, and the sequence in which they are visited. With disaggregated freight behaviour data being scarce, transport modellers hav...

After private cars, minibus taxis are the most common transport mode in South Africa. Especially for low-income citizens living in townships, minibus services are often the only possibility for mobility. Despite the great importance of the mode, there is very little knowledge of routes, fares, and the number of minibuses. Hence, it is difficult to...

Maintenance analysis of an n-unit warm standby system with varying repair rate and the vacation period for the repair facility is studied in this paper. This vacation period occurs after each repair completion. Also, the repair rate of a unit depends on the number of failed units at the epoch of the commencement of the repair. The life time of a un...

As user charging increasingly supplements taxation as a transport financing mechanism worldwide, the need to measure and understand its distributional impacts across affected groups grows more critical. The case of the 185-km Gauteng Freeway Improvement Project in the Johannesburg-Pretoria area of South Africa offers an opportunity to empirically e...

Determining the efficiency of a surface coal mine operation is an essential activity, which can help in deciding on the optimal use of input resources, including effective capital allocation, in generating a desired quantity of coal of a specific quality. Mines operate today in challenging conditions, with diminishing reserves of high-quality coal,...

In evolutionary algorithms, agents’ genotypes are often generated by more or less random mutation, followed by selection based on the fitness of their phenotypes. This paper shows that elements of this principle can be applied in multi-agent transport simulations, in the sense that a router, when faced with complex interactions between heterogeneou...

Modelling large-scale traffic flow systems at a disaggregate level can be data intensive as it requires extensive knowledge about the activities and activity chains of vehicles. This paper focuses on activity chain generation for commercial vehicles. We use a large sample of GPS records to extract a complex network and sample chain characteristics...

Paratransit provides a valuable service offering as a flexible and substitutional mode between formal transit and private car. When it evolves to compete with more formal transit modes, efforts are made to formalise it. As in many developing countries, the South African government generally views paratransit as a necessary nuisance, emerging and ev...

The paper describes the use of GPS data obtained from both commercial and project-specific sources to examine the travel behavior and fuel consumption patterns of drivers over a three-day period in Gauteng Province, South Africa. Data for commercial (truck and light delivery vehicle) traffic are obtained from a commercial fleet management provider,...

South Africa is nearly 20 years into its democracy, yet the legacy of apartheid remains evident and the level of inequality steadily rising. Gauteng province, the economic heart of the country that includes Johannesburg and Tshwane, the capital, carries the burden of many of its formerly relocated citizens still living in poverty on the periphery o...

The impact that commercial vehicles, especially freight, has on traffic is disproportionately large compared to the number of vehicles they represent. Instead of treating commercial vehicles and commercial through-traffic as back- ground noise in our transport planning models, this paper aims to shed light on the characteristics of commercial throu...

We introduce complex network analysis and use a commercial vehicle’s observed trip as a proxy for a business relation between two facilities in its activity chain. We extract facility locations by applying density-based clustering to GPS data of commercial vehicle activities. The network among the facilities is then extracted by analysing the activ...

The most essential and alluring characteristic of a security estate is the estate's ability to provide 24-h security to its residents, of which the continual patrolling of roads and paths is vital. The objective of this paper is to address the lack of sufficient patrol route design procedures by presenting a tabu search algorithm capable of generat...

p>ENGLISH ABSTRACT: It is reasonable to expect that preparation time is needed to ready a repair facility before a repair can be carried out. A three-unit system with a `preparation time’ for the repair facility is studied in this paper. The steady-state availability of such a system is obtained. The asymptotic confidence limits of the steady state...

The state-of-practice in commercial vehicle modelling is based on Gross Domestic Product (GDP) and aggregate economic sectors. There is a lack of understanding of the explicit activity chain characteristics of commercial vehicles. The aim of this research is to contribute to the body of knowledge on commercial vehicle activity chain characteristics...

Road pricing has become a very controversial subject in South Africa with the introduction of the Gauteng Freeway Improvement Project (GFIP). Transport authorities regard road pricing as an effective means to finance road infrastructure and reduce road congestion. On the other hand it has also been proven that policies which have a regressive effec...

To address the underreporting of freight from a transport geography point of view, we present a novel analysis of the time and spatial characteristics of disaggregated commercial vehicle activities. The activities were extracted from raw global positioning system (GPS) data collected in South Africa over a six-month period for more than 30,000 comm...

This paper is on fuzzy stochastic optimisation, an area that is quickly coming to the forefront of mathematical programming under uncertainty. An even stronger motivating factor for the growing interest in this area can be found in the ubiquitous nature of decision problems involving hybrid imprecision. More precisely, we consider a range of situat...

The number of independent and interdependent freight actors (firms), the complex supply chain structures between them, and the sensitivity of shipment data are some reasons that the modeling of freight traffic is lagging its public and private transit counterparts. An agent-based approach was used to reconstruct commercial activity chains and simul...

Commercial vehicles may only represent a small fraction of all road users, but they contribute disproportionately to both congestion and wear of network infrastructure. Yet they are very often treated inadequately as mere noise in state-of-practice transport modelling endeavours. To address the underreporting of freight, this paper provides a novel...

Transport is the price we pay for establishing spatially dispersed firms. Logistics and supply chain literature abound with contributions describing, often qualitatively, the chain structure between firms. Usually only a single focal company is at the centre of the network, and ties between the nodes (companies) are based on contractual agreements...

p>ENGLISH ABSTRACT: Reusable packaging often accumulates downstream in supply chains, resulting in non-revenue-earning relocations. This paper presents a reliable optimisation model under supply and demand uncertainty. Instead of using deterministic forecasted values, we propose a fixed recourse stochastic program that embeds the approximated uncer...

Transport is the heartbeat of the South African economy. It involves the movement of goods from the factory gate to the consumer. More importantly, transport is responsible for moving people, so that they can actively participate in the economy. Previous political policies and the resulting urban planning, as well as extreme socio-economic imbalanc...

South Africa's socio-political history and rapidly changing urban dynamics, coupled with an eclectic mix of first and third world transport infrastructure presents a moving target to even the best traditional transport planning methodologies. A pressing need has emerged for a planning technology that can capture these dynamics and explore its evolu...

The main thrust of this study is the operational scheduling of the continuous coal handling and blending processes when considering multiple, and sometimes conflicting, objectives. A widely applicable generic goal programming model is proposed. Furthermore, assumptions regarding the certainty of demand during different periods are challenged, endea...

In this chapter an intelligent approach is presented in addressing the choice of solution algorithm for a variant of the notoriously hard Vehicle Routing Problem (VRP). To be classified "intelligent" the algorithm is not only able to solve the problem instance, it is also able to analyse the problem environment of an unknown instance, choose an app...

South Africa provides a fascinating interface between the developed and the developing world and poses a multitude of opportunities for enhancing the sustainable development of local cities. The concept of City Logistics is concerned with the mobility of cities, and entails the process of optimizing urban logistics activities by considering the soc...

This paper provides a generic formulation for the complex scheduling problems of Optimatix, a South African company specializing in supply chain optimization. To address the complex requirements of the proposed problem, various additional constraints were added to the classical job shop scheduling problem. These include production downtime, schedul...

Management of a game ranch is an important issue as many game ranches operate on meagre profits, and some even at a loss, as their part-time owners subsidize the ranches from other sources of income. In this paper, we address the sustainable game ranching problem in a South African context through an optimization model. To obtain a faithful picture...

The integration of multiple constraints of the Vehicle Routing Problem (VRP) variants is computationally expensive. Although vehicle routing problems have been well researched, variants are typically treated in isolation, whereas industry requires integrated solutions. Solution algorithms are also tested using benchmark data that are questionable,...