Michele Ottomanelli

A preliminary Petri net model of the transshipment processes in the Taranto container terminal

This paper is a contribution to define a complete and modular model of processes in container terminals, which can be used for simulation, test, monitor and control purposes. A schematic description of the main terminal processes is given, by specifying the resources handling containers in the Taranto container terminal. Then a Petri net formalizes the sequence of operations, each involving the synchronization of resources, for the transshipment process, the efficiency of which seem to be the key to obtain good performances

Quantifying the impacts of horizontal and vertical equity in transit route planning

ABSTRACT Equity refers to a fair sharing of costs or resources. Horizontal equity concerns distribution among individuals or groups with the same necessities, whereas vertical equity should be considered in situations with different levels of needs. This paper deals with transit service, looking at how to make it equitable from a spatial and social point of view. Traditionally equity has been neglected in transit planning, being in the best cases an afterthought during service provision. Hence, we propose a methodology to plan and design public transport routes, which meets the needs of communities fostering equitable accessibility. In this paper we put forward a method to incorporate horizontal and vertical equity goals in a Transit Network Design Problem. We study how the costs of the system change with the attained level of equity and found that higher overall costs may be born if more equitable service provision has to be pursued.

Spatio-temporal Clustering and Forecasting method for Free-Floating Bike Sharing Systems

Free-floating bike sharing systems are an emerging new generation of bike rentals, that eliminates the need for specific stations and allows to leave a bicycle (almost) everywhere in the network. Although free-floating bikes allow much greater spontaneity and flexibility for the user, they need additional operational challenges especially in facing the bike relocation process. Then, we suggest a methodology able to generate spatio-temporal clusters of the usage patterns of the available bikes in every zone of the city, forecast the bicycles use trend (by means of Non-linear Autoregressive Neural Networks) for each cluster, and consequently enhance and simplify the relocation process in the network.

A Generalized Stochastic Petri Net Approach for Modeling Activities of Human Operators in Intermodal Container Terminals

This paper proposes a Petri net (PN) representation of the activities performed by the key human operators for unloading/loading containers in an intermodal maritime container terminal (CT) with a low level of automation. These processes are the core of the export, import, and transshipment cycles executed in the terminal. The aim of this paper is to consider both the human component and the material handling resources, e.g., cranes and transporters, by defining an accurate model, which describes how to coordinate humans and use the system resources necessary for serving mother or feeder ships. The developed generalized stochastic PN-based model is of limited complexity and represents a complete, unambiguous, and readable model of the target process before coding it in the target simulation tool. The modular integrated model is tested and validated by the simulation of typical and perturbed scenarios of the Taranto CT, a real terminal that is taken as a case study for its complexity and similarity to CTs with multiple transport modes.

Design of Priority Transportation Corridor Under Uncertainty

Network design is one of the crucial activity in transportation engineering whose goal is to determine an optimal solution to traffic network layout with respect to given objectives and technical and/or economic constraints. In most of the practical problem the input data are not always precisely known as well as the information is not available regarding certain input parameters that are part of a mathematical model. Also constraints can be stated in approximate or ambiguous way. Thus, starting data and/or the problem constraints can be affected by uncertainty. Uncertain values can be represented using of fuzzy values/constraints and then handled in the framework of fuzzy optimization theory. In this paper we present a fuzzy linear programming method to solve the optimal signal timing problem on congested urban. The problem is formulated as a fixed point optimization subject to fuzzy constraints. The method has been applied to a test network for the case of priority corridors that are used for improve transit and emergency services. A deep sensitivity analysis of the signal setting parameters is then provided. The method is compared to classical linear programming approach with crisp constraints.

Simplified Model for Pedestrian-Vehicle Interactions at Road Crossings Based on Discrete Events System

Road accident reports show that many accidents involve pedestrians, the category of road users generally considered “weak” with respect to other mobility users, and that these accidents occur at pedestrian crossings. Therefore, traffic engineers need simulation tools that can forecast the results of a given design solution and compare the solution with alternatives. A simplified model that simulates interactions between pedestrians and vehicles at road crossings is presented. In the model, the crossing process is represented as a discrete events system, and the model uses basic and easy-to-collect parameters to estimate interactions. Pedestrian behavior in the decision phase is characterized with a gap acceptance criterion, which is based on parameters derived from probabilistic distribution and takes into account the heterogeneity of the pedestrian population. Interaction between pedestrians during the crossing phase is taken into account with a cellular model of the crossing area. The model allows estimation of safety benefits for pedestrians and crossing level of service for both pedestrians and vehicular flows, starting from site geometry and field measurements of flow parameters of pedestrians and vehicles. The model was applied to a real site in a case study. The effects of traffic-calming interventions were also simulated and evaluated.

A real time multi-objective cyclists route choice model for a bike-sharing mobile application

The attractiveness of cycling- and in particular of bike-sharing systems-as a sustainable alternative of transportation is constantly growing, given the undeniable benefits associated with it. The aim of this paper is to present a multi-objective model based on a Fuzzy Inference System to be embedded in a mobile application that could assist cyclists in the selection of the smartest route to follow to reach their destination, in terms of travel costs (distance or time), level of air pollution and road safety. The features of the bike-sharing system (both traditional and free-floating) are considered in the generation of the final path, and also the starting and final stations to prefer (or the closest bike to pick up for the free-floating option) are provided. The proposed optimization model is dynamic, as it is synchronized with geolocated real time data regarding level of congestion and flows on the network, and availability of bikes/racks in the bike-sharing system. The mobile app gives bike users the possibility to plan, personalize and execute their trip with turn-by-turn guidance, allowing them to select the default optimal path, or to choose the desired travel time among the available route options, each of them accompanied by the related air pollution and safety. An application of the model is carried out through a test case to evaluate the proposed approach. Furthermore, a first study regarding the graphic interface of the mobile platform is presented to recommend some guidelines to follow to have a final product effective and bike users-friendly. The final goal is to improve the cycling experience, encouraging at the same time more people to elect the bike as their preferred mode of transportation.