Public transportation systems are often part of strategies to reduce urban environmental impacts from passenger transportation, yet comprehensive energy and environmental life-cycle measures, including upfront infrastructure effects and indirect and supply chain processes, are rarely considered. Using the new bus rapid transit and light rail lines in Los Angeles, near-term and long-term life-cycle impact assessments are developed, including consideration of reduced automobile travel. Energy consumption and emissions of greenhouse gases and criteria pollutants are assessed, as well the potential for smog and respiratory impacts.

Results show that life-cycle infrastructure, vehicle, and energy production components significantly increase the footprint of each mode (by 48–100% for energy and greenhouse gases, and up to 6200% for environmental impacts), and emerging technologies and renewable electricity standards will significantly reduce impacts. Life-cycle results are identified as either local (in Los Angeles) or remote, and show how the decision to build and operate a transit system in a city produces environmental impacts far outside of geopolitical boundaries. Ensuring shifts of between 20–30% of transit riders from automobiles will result in passenger transportation greenhouse gas reductions for the city, and the larger the shift, the quicker the payback, which should be considered for time-specific environmental goals.

An inter-temporal life cycle cost and greenhouse gas emissions assessment of the Los Angeles roadway network is developed to identify how construction decisions lead to embedded impacts and create an emergent behavior (vehicle miles traveled by users) in the long run.

A video of the growth of the network and additional information are available here.

As average temperatures and occurrences of extreme heat events increase in the Southwest, the water infrastructure that was designed to operate under historical temperature ranges may become increasingly vulnerable to component and operational failures. For each major component along the life cycle of water in an urban water infrastructural system, potential failure events and their semi-quantitative probabilities of occurrence were estimated from interview responses of water industry professionals. These failure events were used to populate event trees to determine the potential pathways to cascading failures in the system. The probabilities of the cascading failure scenarios under future conditions were then calculated and compared to the probabilities of scenarios under current conditions to assess the increased vulnerability of the system. We find that extreme heat events can increase the vulnerability of water systems significantly and that there are ways for water infrastructure managers to proactively mitigate these vulnerabilities before problems occur.

The Food-Energy-Water (FEW) nexus is the interaction and the interdependence of the food, energy and water systems. These interdependencies exist in all parts of the world yet little knowledge exists of the complexity within these interdependent systems. Using Arizona as a case study, systems-oriented frameworks are examined for their value in revealing the complexity of FEW nexus. Industrial Symbiosis, Life Cycle Assessment (LCA) and Urban Metabolism are examined. The Industrial Symbiosis presents the system as purely a technical one and looks only at technology and hard infrastructure.

The LCA framework takes a reductionist approach and tries to make the system manageable by setting boundary conditions. This allows the frameworks to analyze the soft infrastructure as well as the hard infrastructure. The LCA framework also helps determine potential impact. Urban Metabolism analyzes the interactions between the different infrastructures within the confines of the region and retains the complexity of the system. It is concluded that a combination of the frameworks may provide the most insight in revealing the complexity of nexus and guiding decision makers towards improving sustainability and resilience.

In the economic crisis Detroit has been enduring for many decades, a unique crisis has emerged with the provision of water that is normally not seen in the developed world. The oversized, deteriorating, and underfunded water provision system has been steadily accruing debt for the water utility since population began to decrease in the 1950s. As a result, the utility has instated rate increases and aggressive water shut off policies for non-paying residents. Residents have consequentially claimed that their human right to water has been breeched.

In this report, I analyze possible solutions to the water crisis from both the water utility and resident perspectives. Since all utility management solutions have very serious limitations on either side of the argument, I have chosen a set of technologies to consider as a part of an impact mitigation plan that can provide alternative sources of water for the people who no longer can rely on municipal water. I additionally propose an adaptive management plan to evaluate the effects of using these technologies in the long-term. The monitoring of the effects of technological mitigations might also help determine if sustainability (efficiency and equity) could be an attainable long-term solution to Detroit’s water crisis.

With potential for automobiles to cause air pollution and greenhouse gas emissions relative to other modes, there is concern that automobiles accessing or egressing public transportation may significantly increase human and environmental impacts from door-to-door transit trips. Yet little rigorous work has been developed that quantitatively assesses the effects of transit access or egress by automobiles.

This research evaluates the life-cycle impacts of first and last mile trips on multimodal transit. A case study of transit and automobile travel in the greater Los Angeles region is developed. First and last mile automobile trips were found to increase multimodal transit trip emissions, mitigating potential impact reductions from transit usage. In some cases, a multimodal transit trips with automobile access or egress may be higher than a competing automobile trip.

In the near-term, automobile access or egress in some Los Angeles transit systems may account for up to 66% of multimodal greenhouse gas trip emissions, and as much as 75% of multimodal air quality impacts. Fossil fuel energy generation and combustion, low vehicle occupancies, and longer trip distances contribute most to increased multimodal trip impacts. Spatial supply chain analysis indicates that life-cycle air quality impacts may occur largely locally (in Los Angeles) or largely remotely (elsewhere) depending on the propulsion method and location of upstream life-cycle processes. Reducing 10% of transit system greenhouse emissions requires a shift of 23% to 50% of automobile access or egress trips to a zero emissions mode.

A corresponding peer-reviewed journal publication is available here:
Greenhouse Gas and Air Quality Effects of Auto First-Last Mile Use With Transit, Christopher Hoehne and Mikhail Chester, 2017, Transportation Research Part D, 53, pp. 306-320,