Sustainability

Using Machine Learning to Understand Causal Relationships Between urban Form and Travel CO2 Emissions Across Continents

Wagner, Felix
Nachtigall, Florian
Franken, Lukas
Milojevic-Dupont, Nikola
Pereira, Rafael H. M.
Koch, Nicolas
Runge, Jakob
Gonzalez, Marta
Creutzig, Felix
2023

Climate change mitigation in urban mobility requires policies reconfiguring urban form to increase accessibility and facilitate low-carbon modes of transport. However, current policy research has insufficiently assessed urban form effects on car travel at three levels: (1) Causality -- Can causality be established beyond theoretical and correlation-based analyses? (2) Generalizability -- Do relationships hold across different cities and world regions? (3) Context specificity -- How do relationships vary across neighborhoods of a city? Here, we address all three gaps via causal graph...

Future Temperature-related Mortality in Latin American Cities under Climate Change and Population Scenarios

Bakhtsiyarava, Maryia
Kephart, Josiah L.
Sanchez, Brisa N.
Ramarao, M. V. S.
Arunachalam, Saravanan
Gouveia, Nelson
Dronova, Iryna
Schinasi, Leah H.
Bilal, Usama
Caiaffa, Waleska T.
Jaffe, Andrea
Diez Roux, Ana V.
Rodríguez, Daniel A.
2025

Background In Latin America, climate change, urbanization, and an aging population are intensifying health risks from extreme temperatures. To accurately assess future temperature-related mortality impacts, evidence that integrates key demographic factors—such as the dynamics of population age composition, mortality rates, and population size—is essential. Methods We projected the impact of nonoptimal temperatures on all-age and age-specific mortality during 2045–2054 for 326 cities in Latin America. Our analysis combined city-level daily mortality counts, gridded temperature data,...

Zero-emission Mobility Strategies: Innovation, Diversity, and Integration

Du, Bo
Liu, Wei
Song, Ziqi
Shaheen, Susan A.
2025

The transportation sector accounts for a substantial proportion of energy consumption and greenhouse gas emissions globally. Electrification of transportation systems has emerged as a promising pathway to achieve sustainability, especially with the widespread adoption of electric vehicles (EVs) in recent decades. Various types of EVs, particularly battery electric vehicles (BEVs), hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs), have gained considerable attention in research, spanning diverse domains, such as battery management, charging infrastructure planning...

Transitioning Ridehailing Fleets to Zero Emission: Economic Insights for Electric Vehicle Acquisition

Ju, Mengying
Martin, Elliot
Shaheen, Susan
2025

Under California’s Clean Miles Standard (or SB 1014), transportation network companies (TNCs) must transition to zero-emission vehicles by 2030. One significant hurdle for TNC drivers is the electric vehicle (EV) acquisition and operating costs versus an internal combustion engine (ICE) vehicle. This study therefore evaluates net TNC driving earnings through EV acquisition pathways—financing, leasing, and renting—along with EV-favoring policy options. Key metrics assessed include (1) total TNC income when considering service fees, fuel costs, monthly vehicle payments, etc., and (2) the...

100% RAP Pilot Project on SBD 40: Material Testing, Life Cycle Assessment, Observations, and Findings

Harvey, John
Buscheck, Jeffrey
Yu, Justin
Butt, Ali
Deng, Hanyu
Rahman, Mohammad
Guada, Irwin
Bowman, Michael
Brotschi, Julian
Mateos, Angel
2025

This report presents data and analysis of a new mix type that has 100% replacement of aggregate and asphalt binder with reclaimed asphalt pavement (RAP) and the addition of a recycling agent. The data were collected from construction of a pilot project on Interstate 40 in San Bernardino County, which included the new mix , HyRAP® (a registered trademark owned by Brooks Construction Company, Inc. and licensed to Manhole Adjusting Inc. but produced under a non-proprietary Caltrans Non- Standard Special Provision), the control gap-graded rubberized hot mix asphalt (RHMA-G), and a dense-graded...

New Methodologies for Airport Environmental Impact Analysis

Hansen, Mark
Ryerson, Megan S.
Marchi, Richard F.
2013

While airports have always had an uneasy relationship with the environment, the relationship has evolved dramatically in recent years. On the one hand, greenhouse gas (GHG) emissions have become a much stronger cause for concern. The global character of the GHG problem challenges established patterns of thinking about airport environmental impacts. At the same time, the canonical airport environmental problem, noise, has been transformed as the result of improving capabilities to redistribute it through procedures enabled by advanced navigation technologies. In this setting, concepts such...

A Mesoscopic Model of Vehicular Emissions Informed by Direct Measurements and Mobility Science

Öztürk, Ayşe Tuğba
Kasliwal, Aparimit
Fitzmaurice, Helen
Kavvada, Olga
Calvez, Philippe
Cohen, Ronald C.
González, Marta C.
2025

Vehicle emissions pose a significant challenge for cities worldwide, yet a comprehensive analysis of the relationship between mobility metrics and vehicle emissions at scale remains elusive. We introduce the Mobile Data Emission System (MODES), a framework that integrates various sources of individual mobility data on an unprecedented scale. Our model is validated with direct measurements from a network of high-density sensors analyzed before and during the COVID-19 pandemic. MODES is used as a laboratory for scaling analysis. Informed by millions of individual trips at a metropolitan...

Use of Recycled Asphalt Pavement in Rubberized Hot Mix Asphalt—Gap-Graded

Mateos, Angel
Harvey, John
Wu, Rongzong
Buscheck, Jeff
Butt, Ali
Guada, Irwin
Bowman, Michael
Rahman, Mohammad
Brotschi, Julian
Yu, Justin
2024

Current Caltrans Standard Specifications for rubberized hot mix asphalt–gap-graded (RHMA-G) do not allow the inclusion of reclaimed asphalt pavement (RAP). This report summarizes the research conducted by the UCPRC in support of the Caltrans-industry initiative “10% RAP in RHMA-G,” whose goal is to evaluate the use of up to 10% RAP (by aggregate replacement) in RHMA-G mixes, provided that the research does not identify significant potential problems for durability. Five pilot projects were built by Caltrans as part the initiative. In each of the pilots, a control RHMA-G (without RAP) and...

Multi-stage Models for Dynamic Ride-Sharing in Taxi Services and Congestion Analysis

Quadrifoglio, Luca
Zhang, Cheng
Sun, Min-Ci
Delle Monache, Maria Laura
Yeo, Yuneil
2024

This research introduces practical optimization model for implementing ride-sharing in taxi services and studies the effects of ride-sharing on the congestion status through the case study of Chicago. Ride-sharing combines trips into one ride-shared trip with the objective of maximizing the total mileage saving. This research proposes a multi-stage model to optimize rider matches, aiming to reduce the total travel distance and enhance the matching of multiple riders. To validate the effectiveness of the model, real taxi data from Chicago is used, demonstrating significant improvements in...

Multimodal Strategies for Mitigating Congestion from Urban Parcel Delivery

Hansen, Mark
Walker, Joan L.
Lin, Pei-Sung
Wang, Zhenyu
Zhang, Yu
2024

The explosive growth in e-commerce, the increasing urgency of de-carbonization, the rapid advances in UAV technology, and the continuous disruptive development of the gig economy create needs and opportunities for dramatic improvements in urban package delivery. E-commerce may greatly increase the demand for such deliveries, traditionally made by truck and van, as urban residents substitute purchases made over the Internet for those acquired in brick-and-mortar stores. To mitigate the congestion impact of truck and van traffic, as well as reduce costs and travel times, last-mile delivery...