Since the 11 September 2001 attacks in the United States and the 7 July 2005 London bombings, geospatial researchers have attempted to utilize GIScience technologies in response to disasters occurring in the microspace of multilevel structures (such as the interior of buildings) in urban areas. Such applications require 3D geographic information systems (GIS) functionalities to represent the three-dimensional structures of urban environments and to conduct 3D GIS-based spatial analyses. These requirements motivate this study to represent the complex internal structure of buildings at a three-dimensional subunit level so as to analyze human behavior in an emergency situation. This article discusses the development of a 3D Navigable Data Model (3D NDM) based on the 3D Geometric Network Data Model and representing pedestrian access within buildings or urban built-environments, which can be modeled as a network of walkway sections and connections. Additionally, this article discusses the design of a geospatial database created to manage the physical and environmental factors of disaster sites that are essential for emergency response. To improve planning and facilitate rescue operations in a decision support system, this article presents (1) a 3D geo-coding method to locate rescue personnel and disaster sites within the reference data (a network representation of a building), (2) a 3D map matching method to define the correlation between the location of bottlenecks or disaster sites and the nearest location on the 3D NDM, which represents the internal structure of the built-environment as a network representation, and (3) an indoor navigation model, based on the Dijkstra algorithm, to identify optimal routes within a multilevel structure by measuring relative pedestrian accessibility and to provide navigation guidance for rescue personnel. Lastly, this article presents the results of an experimental implementation of the 3D NDM using GIS data for a section of the University of North Carolina at Charlotte campus.