Modeling and Simulation of Port-Of-Entry Systems

This paper describes a suite of simulation models for Port-of-Entry (POE) systems, dubbed POESS (POE Simulation System). POE Simulation System was developed with the support of the U.S. Department of Homeland Security (DHS) for use primarily by the U.S. Customs and Border Protection (CBP) agency. POESS aims to assist CBP in POE design and operational decision making. A POESS simulation model of the Bridge of the Americas (BOTA) POE, located at El Paso, Texas, is described as an example.

Fast and sustained secure flows of people and goods across U.S. Ports-of-Entry (POEs) are essential to the U.S. economy and its network of supply chains. In particular, excessive delays at POEs translate into a variety of economic burdens and environmental costs, including personal inconvenience to travelers in terms of time, increased supply chain lead times and their attendant cascading disruptive effects, and an elevated carbon footprint resulting in environmental and public health consequences.

The U.S. Customs and Border Protection (CBP) agency is the nation’s largest law enforcement agency, responsible for securing U.S. borders while facilitating lawful travel and trade across its POEs. As such, CBP plays a key role in supporting the nation’s physical and economic security. CBP needs to find efficient and cost effective solutions to the problem of managing traffic across POEs with fluctuating traffic levels. More specifically, CBP needs detailed and flexible simulation models serving as in-vitro labs that answer “what-if” questions that support POE optimized planning, such as decisions on POE reconfiguration, ex-pansion, and response to disruptions. Accordingly, DHS funded a project to develop such a simulation platform and construct a suite of detailed and accurate simulation models of key POEs (DHS/CBP, 2016). This paper summarizes the salient features of the software tool created over the first two stages of this project (from 1/2016 to 6/2017). This tool has been dubbed POESS (POE Simulation System), and its initial users will be CBP analysts and possibly DHS-affiliated preparedness and response organizations.

Port-of-Entry Simulation System Overview

POESS is designed to serve as an in-vitro laboratory for experimentation and answering “what-if” questions related to effective and cost efficient traffic management across POEs. The simulation models provide de-cision support, primarily for strategic longer-term planning, such as capacity planning (e.g., expansion of existing POEs or creation of new ones before traffic growth overwhelms current POEs), and optimization (e.g., selecting the best configuration among a set of candidates). They can also support other DHS planning activities pertaining to hypothetical adverse scenarios, including (a) evacuation of a local population due to a natural or man-made disaster, such as inclement weather (e.g., impending hurricane or flooding), chemical accident, etc.; (b) loss of POE infrastructure (e.g., terrorist event resulting in POE partial or complete clo-sure); and (c) traffic-disrupting events (e.g., an accident resulting in lane closures at a POE). POESS pro-duces a set of performance metrics of interest to POE operations, to be described in the next section, com-puted from a single or multiple replications.

Port Simulation Model Components

Bridge of the Americas (BOTA) POE’s Privately-Owned Vehicle (POV) inspection area (green) and Commercially-Owned Vehicle (COV) inspection area (red)

A POESS model consists of both immobile objects and mobile ones. The key immobile objects consti-tute the POE infrastructure: incoming and outgoing roads, incoming plazas, inspection booths, devanning docks and inspection equipment (X-ray and radiation facilities). The key mobile entities are vehicles that pass through the POE and handled by inspection personnel. The layout of a POE in a POESS simulation model is visualized by superimposing it on a geographical map of the POE facility and its vicinity. To facilitate experimentation, we developed a graphical user interface (GUI) with a dynamic editor that permits the user to pause a simulation and alter its parameters (including incoming traffic loads, inspection capacities, lane reconfiguration, and the introduction of physical traffic obstructions), and resume or restart runs. In a similar vein and to enhance model behavior, POESS takes advantage of traffic and statistics animation. POESS is coded in Java over the AnyLogic simulation platform (Borschchev, 2013), which offers a rich set of graphical tools, including rendering in 2D and 3D views, a debugger, visual and textual model construction, animated simulation runs and dynamic statistics collection (charts and plots). AnyLogic affords an organic integration of multiple modeling paradigms, of which POESS makes use of discrete-event and agent-based simulation.

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