Installing PECAS


PECAS is distributed as a complete demonstration simulation model, based on the Baltimore MD region. The PECAS software is contained in a java .jar file within this distribution, but the .jar file is not distributed separately since PECAS works within an entire spatial economic simulation system, including the input data and other simulations (such as a travel demand model.) To begin, familiarize yourself with the theory of PECAS by reading the theoretical formulation document. After you are somewhat familiar with the theory, read the document on downloading and installing the PECAS Demonstration Model. Installing PECAS several programs including Java, Python and PostgreSQL, which is a powerful database program. The document explains how to install the programs but also describes where to copy the Demo model data, which has two main components: the directory with associated files and the tables to load into PostgreSQL. This document also explains how to run the model. The PECAS Software and associated demo model data is in a .rar compressed file at this link, some of the documentation and much of the additional required software setup files for Windows computers is available at this link.

Familiarization with the data structure


In order to become familiar with the directory structure, files and tables, and how data interchange is performed inside of PECAS, it is recommended to download the PECAS file interchange and file description and SD ER Diagram. The first one describes which files are in which directories, but also indicates which files belongs to the Activity Allocation (AA) module, and which tables are required by the Space Development (SD) module. In addition, this figure shows how the files from these modules interact with the Transportation module and which files are used to indicate any policy analysis (land use policy, trends and economic policy or transportation policy). The second one presents a detailed description of the attributes of each table of the SD module.
File Interchanges Screenshot

Demonstration transportation demand model


PECAS is designed to work with a transportation demand model, to establish travel conditions and the connectivity between places. The demonstration model includes a simplified open-source Frank-Wolfe assignment algorithm. Please review the functionality and operation of the simplified travel demand model.

Model output visualization (MapIt)


To enable graphical review of results by multiple users, a web program called “MapIt” was developed. As a model simulation occurs, model output is loaded into a PostgreSQL spatial database. (In the case of the demo model, this data is loaded by a script called “runYearLoader_psycopg.py”, after the entire simulation runs, rather than as the simulation is running.) MapIt uses Mapserver, Django and other web application programming solutions to enable the selection and viewing of model output data as maps in their browser. The maps are also served as industry-standard GIS layers, so that analysts familiar with different GIS programs (QGIS, ArcGIS, Google Earth, etc.) can import the spatial data selected and compiled with MapIt into more powerful (non browser-based) visualization and mapping programs. Installing software on a server is more difficult, and considerations of privacy, security, and reach need to be considered. You may wish to work with an Information Technology professional experienced in server software installation and maintenance to install MapIt on a server computer. Once MapIt is installed, follow the instructions for using it.

Use cases for PECAS


Previous examples are especially useful for understanding the uses of PECAS. Two papers describing uses of the Baltimore PECAS model include the overview of the PECAS Demo Model and an Investigation of Zoning Policy in Baltimore.

Instructions for testing scenarios with PECAS


PECAS is a flexible and inclusive spatial economic framework, and scenarios can be evaluated and tested in many ways. However, there are some standard ways to test scenarios.