Policy

Secondary trading of airport slots: Issues and challenges

Wang, Yanjun
Wang, Mengyin
Xu, Weishan
Mark Hansen
2023

Most Level 3 airports around the world suffer severe congestion and flight delays. Airlines have to obtain airport slots in order to schedule flights at such airports. The main way for airlines to acquire slots is primary slot allocation, in which a slot coordinator distributes slots to airlines according to certain rules and regulations. Due to excessive demand for slots and restrictions on allocation rules, it is difficult for some airlines to obtain the desired slots in this manner. Another way for airlines to obtain slots is through secondary slot trading, in which slots can be...

Advancing Alternative Fuel Aviation Technologies in California

Liu, Yati
Mark Hansen
Ro, Jin Wook
Murphy, Colin W.
2025

The aviation sector in California is facing increased pressure to reduce its carbon footprint, leading to a growing interest in alternative fuel aviation (AFA) technologies such as sustainable aviation fuel (SAF), as well as electric- and hydrogen- powered aircraft. The report develops a California Aviation Energy Model (CAVEM), examining various AFA technologies and analyzing possible policy options. The analysis emphasizes the importance of SAF in the short term, with projections indicating sufficient supply for intrastate flights and capped vegetable oil-based fuel consumption. Long-...

Urban Science: Integrated Theory from the First Cities to Sustainable Metropolises

Lobo, José
Alberti, Marina
Allen-Dumas, Melissa
Arcaute, Elsa
Barthelemy, Marc
Bojorquez Tapia, Luis A.
Brail, Shauna
Bettencourt, Luis
Beukes, Anni
Chen, Wei-Qiang
Florida, Richard
Marta Gonzalez
Grimm, Nancy
Hamilton, Marcus
Kempes, Chris
Kontokosta, Constantine E.
Mellander, Charlotta
Neal, Zachary P.
Ortman, Scott
Pfeiffer, Deirdre
Price, Michael
Revi, Aromar
Rozenblat, Céline
Rybski, Diego
Siemiatycki, Matthew
Shutters, Shade T.
Smith, Michael E.
Stokes, Eleanor C.
Strumsky, Deborah
West, Geoffrey
White, Devin
Wu, Jingle
Yang, Vicky Chuqiao
York, Abigail
Youn, Hyejin
2020

Urban science seeks to understand the fundamental processes that drive, shape and sustain cities and urbanization. It is a multi/transdisciplinary approach involving concepts, methods and research from the social, natural, engineering and computational sciences, along with the humanities. This report is intended to convey the current “state of the art” in urban science while also clearly indicating how urban science builds upon and complements (but does not replace) prior work on cities and urbanization in many other disciplines. The report does not aim at a fully comprehensive synopsis of...

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
Marta Gonzalez
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...

An interdisciplinary Data-science Approach to Managing Natural Hazards Risk

Pais, Cristobal
Kim, Minho
Radke, John
Marta Gonzalez
2024

Natural hazard risk management is a demanding interdisciplinary task. It requires domain knowledge, integration of robust computational methods, and effective use of complex datasets. However, existing solutions tend to focus on specific aspects, data, or methods, limiting their impact and applicability. Here, we present a general data-driven framework to support risk assessment and policy making illustrating its usage in the context of fire hazard by integrating three unique datasets of fire behavior, street network, and census data for the whole state of California. We show that...

Share, Collaborate, Benchmark: Advancing Travel Demand Research through rigorous open-source collaboration

Caicedo, Juan D.
Guirado, Carlos
Marta Gonzalez
Joan Walker
2024

This research foregrounds general practices in travel demand research, emphasizing the need to change our ways. A critical barrier preventing travel demand literature from effectively informing policy is the volume of publications without clear, consolidated benchmarks, making it difficult for researchers and policymakers to gather insights and use models to guide decision-making. By emphasizing reproducibility and open collaboration, we aim to enhance the reliability and policy relevance of travel demand research. We present a collaborative infrastructure for transit demand prediction...

Share, Collaborate, Benchmark: Advancing Travel Demand Research Through Rigorous Open-source Collaboration

Caicedo, Juan D.
Guirado, Carlos
Marta Gonzalez
Joan Walker
2024

This research foregrounds general practices in travel demand research, emphasizing the need to change our ways. A critical barrier preventing travel demand literature from effectively informing policy is the volume of publications without clear, consolidated benchmarks, making it difficult for researchers and policymakers to gather insights and use models to guide decision-making. By emphasizing reproducibility and open collaboration, we aim to enhance the reliability and policy relevance of travel demand research. We present a collaborative infrastructure for transit demand prediction...

Long-term Validation of Inner-urban Mobility Metrics Derived from Twitter/X

Knoblauch, Steffen
Groß, Simon
Lautenbach, Sven
de Aragão Rocha, Antonio Augusto
Marta Gonzalez
Resch, Bernd
Arifi, Dorian
Jänisch, Thomas
Morales, Ivonne
Zipf, Alexander
2025

Urban mobility analysis using Twitter as a proxy has gained significant attention in various application fields; however, long-term validation studies are scarce. This paper addresses this gap by assessing the reliability of Twitter data for modeling inner-urban mobility dynamics over a 27-month period in the metropolitan area of Rio de Janeiro, Brazil. The evaluation involves the validation of Twitter-derived mobility estimates at both temporal and spatial scales, employing over 1.6 × 1011 mobile phone records of around three million users during the non-stationary mobility period from...

Sharing, Collaborating, and Benchmarking to Advance Travel Demand Research: A Demonstration of Short-term Ridership Prediction

Caicedo, Juan D.
Guirado, Carlos
Marta Gonzalez
Joan Walker
2025

This research foregrounds general practices in travel demand research, emphasizing the need to change our ways. A critical barrier preventing travel demand literature from effectively informing policy is the volume of publications without clear, consolidated benchmarks, making it difficult for researchers and policymakers to gather insights and use models to guide decision-making. By emphasizing reproducibility and open collaboration, we aim to enhance the reliability and policy relevance of travel demand research. We demonstrate this approach in the field of short-term ridership...

Contracting For Public Transit Services: Evaluating the Tradeoffs

Karen Trapenberg Frick
Taylor, Brian
Wachs, Martin
2008

When considering public transit, travelers typically judge whether it serves desired destinations in a timely manner and at a reasonable cost – often in comparison to traveling by private vehicle. How public transit agencies choose to operate their services – their networks, service frequency, and fare structures – to compete with private vehicles and provide mobility for those without them is the subject of this synthesis. Specifically, we examine the "make" or "buy" decision in public transit: Should government agencies operate (make) transit service directly, or does it save money to...