The objective of this EArly-Concept Grant for Exploratory Research (EAGER) project is to study data collected after earthquakes and other events to create a model to describe the behavior of the "gray", or built, and the "green", or landscape systems, as a whole. "Civil infrastructure" is a term that describes the engineering underpinnings of society such as water supply, power delivery and roadways. Sometimes it is called "gray" infrastructure because it tends to be built of concrete and other materials. Often, engineers analyze only one part of the infrastructure at a time. For example, most traffic lights on roadways are designed to work when power is available. Power outages are assumed to be brief enough that a long-term back-up plan is not required. However, it has become apparent in recent years that the functioning of built systems comprising the infrastructure such as roadways and power supply are not independent, but rather interdependent. Power outages affect roadways and vice-versa: If roadways are closed, crews cannot fix damaged power lines. Also, recent disasters such as the 2011 Tohoku earthquake in Japan indicate that it is important to include green systems such as trees and rivers in examining the infrastructure after major events. Closer to home, water systems for drainage in US cities include both built systems such as piping as well as "green" systems such as forests and other landscapes.
This work will significantly expand existing databases, examine case studies and use mathematical methods such as input-output models and influence diagrams to build a framework for describing the behavior of the entire infrastructure. The results will include the creation of a website for data collection and dissemination, published articles on the research, and presentations to students and practicing engineers. A fully operating infrastructure is critical for the proper functioning of society. This research is a good investment because it provides a bridge between engineers and others with different perspectives, such as biophysical and social scientists, for the modeling of infrastructure behavior. Because the United Nations has identified the lack of appropriate infrastructure as a global challenge, this research is timely. This research will be a major step forward towards cataloging data on and models of the green systems that are analogous to the gray or built systems in the same format. With these data, the research community will be better able to assess the performance of the infrastructure for various natural hazards such as earthquakes and hurricanes. The research is transformative because it will produce an approach to infrastructure design as a whole. Results from the proposed project will transform the instruction and implementation of the infrastructure system design process in academia and in practice.
Our research focused on modeling green infrastructure as complementing gray or built infrastructure systems. A simple diagram illustrates this concept as shown in Figure 1. Green infrastructure is defined by the Conservation Fund as "a network of natural areas and open spaces such as woodlands, wetlands, trails and parks that conserves ecosystems, helps sustain clean air and water and provides many other benefits to people and wildlife." Rottle [Urban Green Infrastructure for Climate Benefit, Nordic Journal of Architectural Research, 2013] has defined urban green infrastructure as five systems – social, biological, hydrological, circulatory and metabolic - that provide integrated multiple benefits. In our project model, green infrastructure complements or contributes to urban gray services through hydrological systems such stormwater and urban drainage; metabolic systems such as distributed energy systems of solar panels and efficient building heating-ventilation and air-conditioning or HVAC; and circulatory transportation systems such as bike paths and pedestrian trails. We proposed recovery and fragility models for urban forests similar to those for gray systems such as power delivery, as well as being interdependent as illustrated in Figure 2. A presentation of preliminary results [Building Community Resilience Through Improved Infrastructure] was provided at the ASCE Structures Congress 2013 by the principal investigator. Two graduate research assistants were funded by this project.
