Massimo Di Francesco

Università degli studi di Cagliari | UNICA · Mathematics and Computer Science

In Proof-of-Payment Transit Systems (POP-TSs), fare evasion is a crucial issue for Transit Agencies (TAs) and/or Public Transport Companies (PTCs) worldwide. The related research background is based on the standard ratio between evaders and inspected passengers, whereas no research quantified the risk of fare evasion in POP-TSs. The objective of th...

This work introduces a complex variant of the timetabling problem, which is motivated by the case of Italian schools. The new requirements enforce to (i) provide teachers with the same idle times, (ii) avoid consecutive days with heavy workload, (iii) limit multiple daily lessons for each class, (iv) introduce shorter time units to differentiate en...

Since transfers increase the connectivity of routes, they improve the characteristics of transit networks. Designing and managing transfers are well-investigated issues arising at the tactical and operational level. Conversely, the monitoring phase was rarely faced to verify the consistency between well planned and/or delivered transfers. In this p...

We consider polyhedral separation of sets as a possible tool in supervised classification. In particular, we focus on the optimization model introduced by Astorino and Gaudioso (J Optim Theory Appl 112(2):265–293, 2002) and adopt its reformulation in difference of convex (DC) form. We tackle the problem by adapting the algorithm for DC programming...

In public transit networks, transfers occur when more than one route is used to connect origins and destinations. Much research has been done to investigate the design and management of transfers at the tactical and operational levels. However, very few studies have investigated the monitoring phase to check a posteriori if transfers are well plann...

In high frequency transit services, irregularity is unavoidable due to the stochastic context in which bus services are operated. As a result, the measurement of the regularity and the identification of possible irregularity sources provide an opportunity to maintain scheduled headways. As far as the authors know, the irregularity was typically inv...

We investigate a multiperiod drayage problem in which customers request transportation services over several days, possibly leaving the carrier some flexibility to change service periods. We compare three approaches for the problem: a path-based model with all feasible routes, a “Price-and-Branch” algorithm in which the pricing is formulated as a c...

This paper investigates a service network design problem, which is motivated by the case of freight transportation in a port city. We describe the novel features of this problem, which are based on the possible (but still unexploited) knowledge on the composition of the disaggregated loads in containers and semitrailers entering the port. In this p...

This paper is motivated by the case of a forwarder dealing with inland transportation planning, from a seaport, of inbound containers filled with pallets having different destinations in the land‐side. Although the forwarder is not the owner nor controls any vehicle, he is required to plan both the assignment of containers to intermediate depots, w...

We present a new disaggregated formulation of the Capacitated Concentrator Location Problem (CCLP) using the notion of cardinality of terminals assigned to a concentrator. This formulation consists of O(mnn) variables and constraints, where m denotes the number of concentrators and n the number of terminals, respectively. We prove that this extende...

This paper investigates a drayage problem, where a fleet of trucks must ship container loads from a port to importers and from exporters to the same port, without separating trucks and containers during customer service. We present three formulations for this problem that are valid when each truck carries one container. For the third formulation, w...

This paper investigates a drayage problem, which is motivated by a carrier providing door-to-door freight transportation services by trucks and containers. The trucks carry one or two containers to ship container loads from a port to importers and from exporters to the same port. The problem is modeled by a set covering formulation with integer var...

This paper addresses a drayage problem, which is motivated by the case study of a real carrier. Its trucks carry one or two containers from a port to importers and from exporters to the port. Since up to four customers can be served in each route, we propose a set-covering formulation for this problem where all possible routes are enumerated. This...

In one-way carsharing users are allowed to return cars to locations different from those where they were picked up. but directional imbalances in their requests result in the accumulation of unnecessary cars in some areas, whereas other areas face car shortages. To correct tins situation, we investigate the introduction of a new relocation service...

Manpower management is a complex problem for transshipment container terminals, because different requirements must be taken into account in the short-term plan to properly assign workers to shifts, tasks and operations, while accounting for some decisions already made in the long-term plan. An optimisation model is formulated to discuss the decisi...

Archived Automatic Vehicle Location (AVL) data are widely used in bus transportation, but typically contain anomalies, such as missing data points and unseen bus overtakings. These anomalies may alter the measurement of time reliability (i.e., headways and schedule time deviations) of buses at stops with respect to passenger experiences. However, i...

Time reliability problems are unavoidable, owing to the stochastic context in which bus services are operated. Therefore, characterizing their reliability and understanding possible sources of unreliability provides an opportunity to keep buses on schedule and/or maintain planned headways. Measuring time reliability is technologically feasible by a...

This paper investigates the short-term manpower planning problem regarding transhipment container terminals. It consists of determining shifts, tasks and activities of the manpower working in these terminals in order to serve vessels in time intervals, which typically do not overlap with personnel shifts. This complex problem is modelled by an inte...

Recent studies to evaluate the quality of transit service are generating a good amount of renewed interest in an old idea, the passenger's perspective; this new interest stems from recognizing that transit service quality should be characterised, measured, and managed by parameters capturing both passenger and transit operator perspectives. However...

Manpower management is a complex problem for transshipment container terminals, because different requirements must be taken into account in the short-term plan to properly assign workers to shifts, tasks and operations, while accounting for some decisions already made in the long-term plan. An optimisation model is formulated to discuss the decisi...

The goal of the research is to propose an optimization-based methodology for the evaluation of retrofit incentives, using as a benchmark the wide data collection reported by the ENEA Italian Agency since 2007. To determine the best mix of energy retrofit measures for different areas of Italy, two Linear Programming models are proposed. The first mo...

The main goal of the present research is to propose an optimization-based methodology for the evaluation of economic incentives on building energy retrofits. Basing on the main facts emerging from the adoption of the key policies and financial instruments currently in force at European level (particularly in Italy), it can be helpful to outline the...

This paper investigates punctuality at bus stops. Although it is typically evaluated from the point of view of bus operators, it must also account for users, as required in recent service quality norms. Therefore, evaluating punctuality at bus stops is highly important, but may also be a complex task, because data on both bus arrivals (or departure...

man resources allocation plays a key role in Transhipment Maritime Container Terminals to achieve high levels of productivity and provide high quality services to shipping companies. The deep interest of container terminals in this issue can be supported by optimization methods. In this work, an optimization model is proposed to determine the optim...

The inland repositioning of empty containers is a crucial problem for shipping companies providing door-to-door transport services to customers. This activity consists of the allocation of heterogeneous fleets of empty containers between inland depots and ports, so that they can be properly positioned in anticipation of future customer requests. Th...

This paper presents the case study of an Italian carrier, Grendi Trasporti Marittimi, which provides freight transportation services by trucks and containers. Its trucks deliver container loads from a port to import customers and collect container loads from export customers to the same port. In this case study, all import customers in a route must...

Knowledge of ridership data on bus routes is pivotal for the quality and the efficient operational planning of public transport companies. Automatic Passenger Counting can represent a powerful resource for supporting this activity, because it can provide a databank of accurate counts. However, relevant challenges, such as the matching of data to th...

This paper investigates the maritime repositioning of empty containers when their demand is uncertain. It involves moving empty containers from import-dominant ports to export-dominant ports in anticipation of future demands. In order to consider demand uncertainty, the problem is addressed by a stochastic programming approach, in which different s...

Bus regularity is a key element for high-frequency transportation systems: it represents a measure of service quality for both users and transit agencies. Therefore, evaluating the regularity is highly important, but may also be a complex task in medium-size cities, because of the huge amount of data, which must be collected and processed effective...

This paper addresses a new routing problem, where container loads must be shipped from a port to importers and from exporters to the port by trucks carrying one or two containers, without separating trucks and containers during customer service. We describe the problem, formulate an optimization model and propose a metaheuristic. It determines the...

The inland repositioning of empty containers is a crucial problem for shipping companies providing door-to-door transport services to customers. This activity consists of the allocation of heterogeneous fleets of empty containers between inland depots and ports, so that they can be properly positioned in anticipation of future customer requests. Th...

This paper investigates the maritime repositioning of empty containers under uncertain demand. In order to consider data uncertainty, the problem is addressed by a stochastic programming approach, in which different scenarios are included in a multi-scenario optimization model and linked by non-anticipativity conditions. Numerical experiments show...

a b s t r a c t This paper addresses the problem of repositioning empty containers in maritime networks under possible port disruptions. Since drastically different futures may occur, the decision making process for dealing with this problem cannot ignore the uncertain nature of its parameters. In this paper, we consider the uncertainty of relevant...

Bus regularity is a crucial factor for high frequency public transport systems, because it represents a relevant measure of quality of service for both users and transit agencies. Low regularities for users are associated with bunching phenomena or large gaps between buses, which result in low attractiveness of the service for transit agencies. The...

Bus regularity is a key element for high frequency transit systems: it represents an appropriate measure of quality of service for both users and transit agencies. Therefore, evaluating the regularity is extremely desirable, but may also be a complex task in medium-size-cities, due to the huge amount of data, which must be collected and processed e...

This paper addresses a container maritime-repositioning problem where several parameters are uncertain and historical data are useless for decision-making processes. To address this problem, we propose a time-extended multi-scenario optimization model in which scenarios can be generated taking into account shipping company opinions. We then show th...

The street-turn option represents a major strategy for the profitability of shipping companies supplying container-based transportation. This option consists in the distribution of trucks delivering loaded containers to import customers, the subsequent allocation of empty containers to export customers and the final dispatch of loaded containers to...

This study addresses a repositioning problem where some ports impose several restrictions on the storage of empty containers, sailing distances are short, information becomes available close to decision times and decisions are made in a highly uncertain environment. Although point forecasts are available and probabilistic distributions can be deriv...

Due to the global trade imbalance, some ports tend to accumulate unnecessary empty containers, while others face container shortages. As a consequence, shipping companies must properly reposition their empty containers between ports. A major difficulty in this activity consists in the many sources of uncertainty. Sometimes historical data are usele...

This paper investigates the maritime repositioning of empty containers when their demand is uncertain. It involves moving empty containers from import-dominant ports to export-dominant ports in anticipation of future demands. In order to consider demand uncertainty, the problem is addressed by a stochastic programming approach, in which different s...

This paper proposes a mathematical programming approach for empty container management. Since directional imbalances in trade activities result in a surplus or shortage of empty containers in ports and depots, their management can be thought of as a min cost flow problem whose arcs represent services routes, inventory links and decisions concerning...

This thesis investigates the reasons why nowadays empty container repositioning represents a crucial issue for the shipping industry. Moreover, taking into account information collected through surveys and meetings with industrial experts, we provide a broad overview of current logistic practices for the management of empty containers in the contex...