Passenger flow simulation in a hub airport: An application to the Barcelona International Airport

This paper describes a conceptual model intended to be applied in a general approach to the micro-simulation of hub airports terminals. The proposed methodology is illustrated with the development of a simulation model originally intended to help in the design of the new terminal at Barcelona International Airport. This model represents in detail, among many other elements, passengers’ flows in the different areas of these complex facilities. Agent-based simulation techniques were included to represent the different actors’ behaviors, and a formal representation of the model using Specification and Description Language (SDL) was used to represent the complexity of all the system elements. To pre-process a diverse and considerable amount of raw data provided by airport designers and other sources to feed the simulation environment Flight Planner Manager was developed as a toolkit to parameterize the different model factors and to generate required specific input data. This project was conducted over 3 years leading to the development of a system not only conceived to assess in the airport initial design process but also to constitute a recurrent decision taking instrument to dynamically optimize terminal management and operations. 2014 Elsevier B.V. All rights reserved. 1. Objectives and methodology The different and asynchronous flows merging in the terminal areas represent a considerable challenge for modern airport management, even considering the well-known or easily predictable passengers’ behaviors in this specific and regulated context. Many rules are linked to arrivals and departures patterns, workers routines, schedules and conditions, as long with specific airport operations and activities (check-in, access control, shopping or food and beverages areas distribution and characterization, waiting spaces. . .). Airport managers emphasizes the importance of aspects like security, efficiency, bottleneck avoidance, quality of services, comfort, ease of use or sustainability and rationalization of costs, among many others. A large amount of questions need to be solved ranging from the assignment of arriving flights to available gates [3], to problems related with recurrent or unexpected delays, access control dimensioning and reconfiguration, or the importance of public transportation systems scheduling [16,19]. This paper is focused on the modeling of space requirements and flow management in the main terminal building and related areas of a hub airport. The objectives to cover with the required simulation based decision tool are necessarily P. Fonseca i Casas et al. / Simulation Modelling Practice and Theory 44 (2014) 78–94 79 multiple: (i) to assess the design and construction of a new airport terminal taking in account economic and social forecasting and other strategic considerations (this issue comprehends spaces, flows and resources and facilities involved in a complex and costly construction process); (ii) to produce and validate a decision tool as a basis to evaluate operational alternative scenarios under a dynamic management. The work is organized as follows: in this first section the objectives and the methodology are introducedwhile in Section 2 we detail how the different flows are considered. In Section 3 we describe the model globally representing the airport and in Section 3.2 results obtained from experimentation with the implemented model are shown. Finally in Section 4, some concluding remarks are noted and further improvements and other work are suggested. Space requirements are a key factor in airport management [8,13,23]. Models dealing with space requirements are frequently based on differential equations or queuing theory [14,15]. These approximations are not however sufficient to provide a detailed characterization of several complex flow patterns. Additionally an airport is really a complex system and to understand all the flows and their behavior requires a multidisciplinary approach to achieve their characterization. These internal and external assessors need tools to evaluate and sustain their specific proposals by means of objective and understandable tools and protocols. This is of course common to other complex systems and a considerable amount of knowledge and expertise has been already developed. Nevertheless, infrastructures of the dimensions and costs considered in this project represent a considerable effort in terms of tools’ conceptualization, developments, testing, results validity, credibility and usability along the whole engineering process. These complex issues must be simultaneously envisaged in order to give an adequate answer to the project planned objectives. Main challenges we face are to obtain an accurate and valid information of the system, to build a complete and unambiguous model from this information and to generate results in a time span adequate to the project strategic requirements (infrastructure definition), and to the operational requirements (the daily use of the tool). As we will detail in Section 3 at least six different teams’ categories of specialists should be involved (see Table 1 for the teams’ definition in Barcelona project). Airport authorities’ involvement under a concurrent and collaborative schema propitiates that the final model reasonably meets their expectations. This commitment contributes effectively to resulting model validity and accreditation. It definitively facilitates the acceptation and implementation of specific solutions selected among a set of proposed scenarios for the new facility. The validation schema we followed was Independent Verification and Validation (IV&V) [22]. Particularly Barcelona Airport project validation was conducted by external assessors concurrently with the design and development of the simulation model phases. Final validation and accreditation involved not only this team but also other experts and airport authorities. These teams frequently use different tools and languages. A principal challenge is to collect this knowledge and to embody it in a commonly accepted model framework. To coordinate the project development it was necessary to establish a formal language to simplify and facilitate communication and interactions transversally among teams’ members. Formal languages that can be used for this purpose include Petri Nets [4] and Forrester diagrams [24]. In our formulation we use Specification and Description Language (SDL) for the model definition. We also selected a visual simulation environment, Witness [11,12], to facilitate the discussion and the understandability of the different constitutive blocks of the model and for the implementation of some of the main simulated processes. SDL is a formal object-oriented language defined by the International Telecommunication Union – Telecommunication Standardization Sector (ITU–T) as Recommendation Z.100 [10]. This language is designed to specify complex, event-driven, real-time, interactive applications involving many concurrent activities, using discrete signals to enable communication [5,10]. SDL is a powerful and modern language widely used in different areas -not only in simulationand can be easily combined with UML. Model definition is supported by different types of components: Structure: system, blocks, processes and processes hierarchy. Behavior: defined through the different processes. Data: based on abstract data types (ADT). Table 1 Roles of the different teams involved in Barcelona project (conducted by UPC-BarcelonaTech, INDRA, AENA and other consulting firms).