Recent its_papers items

Strategies for Improving Community College Access in California

Mon, 31 Aug 2026 00:00:00 +0000

In California, transportation plays a key role in community college access because many community college districts have satellite campuses, have limited transportation options, and tend to not have on-campus housing. To better understand the mobility challenges students face accessing community colleges and provide potential policy strategies to overcome these challenges, the researchers interviewed local transportation agencies, community college administrators, and students at five California community colleges between September 2022 and October 2023. Participants were asked about available transportation options for community college students, typical student travel patterns, and the resources needed to support improved community college transportation access. Small group discussions with students focused on student travel patterns, mobility challenges, and opinions on potential strategies to improve access. In addition, we reviewed state legislation on student transportation...

Reduce Emissions and Improve Traffic Flow Through Collaborative Autonomy

Mon, 31 Aug 2026 00:00:00 +0000

This report explores opportunities for employing autonomous driving technology to dampen stop-and-go waves on freeways. If successful, it could reduce fuel consumption and emissions. This technology was tested in an on-road experiment with 100 vehicles over one week. Public stakeholders were engaged to assess the planning effort and feasibility of taking the technology to the next level: a pilot involving 1000+ vehicles over several months. Considerations included the possible geographical boundaries, target fleets of vehicles, and suitable facilities such as bridges or managed lanes. Flow smoothing technology may improve the user experience and operations of managed lanes or bridges, however it may require external incentives such as reduced tolls to entice the traveling public to use it. This must be matched with other goals such as verifying vehicle occupancy. It might be possible for some hybrid solution that addresses both challenges to provide a way forward. A concept of...

Advanced Air Mobility: Opportunities, Challenges, and Research needsfor the State of California (2023-2030)

Mon, 31 Aug 2026 00:00:00 +0000

Advanced air mobility (AAM) is a broad concept that enables consumers access to air mobility, goods delivery, and emergency services through an integrated and connected multimodal transportation network. AAM can provide short-range urban, suburban, and rural flights of about 50-miles and mid-range regional flights up to a several hundred miles. State law delegates responsibility for oversight in aviation primarily to the California Department of Transportation (Caltrans). This white paper presents an overview of the state of the market, such as the aircraft under development and forecast market growth and discusses factors that could facilitate the development of AAM or pose risks to its deployment or to the public, including the safety and the regulatory environment, airspace and air traffic management, security, environmental impacts, weather, infrastructure and multimodal integration, workforce and economic development, social equity, and community engagement and social acceptance....

The Impact of Air Travel on the COVID-19 Pandemic Spread in the United States

Thu, 6 Aug 2026 00:00:00 +0000

This paper develops models to quantify the dynamics of the impact of domestic air travel on the spread of the COVID-19 pandemic in the United States, using a wide range of datasets covering the period from March to December 2020 – when international travel was restricted and became a minor source of new COVID-19 cases across country borders. With the help of flight operation data, we first develop a novel approach to estimate the county-level daily air passenger traffic, which combines passenger load factor estimates and information about the air traffic distribution. Cross-sectional models using aggregated county-level variables are estimated. While this study focuses on air travel variables, we also control for potential spatial autocorrelation and other relevant covariates, including vehicle miles traveled (VMT), road network connectivity, demographic characteristics, and climate. The model results indicate that air travel has a strong and positive impact on the initial pandemic...

Sequential Prediction of Go-Around Occurrence

Thu, 6 Aug 2026 00:00:00 +0000

A go-around is an aborted landing event of an aircraft that is on final approach. Go-arounds are costly and detrimental to safety. Building upon our previous work in go-around detection and analysis of feature contributions, we investigate different learning models and prediction regimes for making sequential predictions of go-around probabilities based on realized trajectory data and environment factors as the aircraft proceeds on its approach. This paper develops and compares the performance of different learning algorithms and prediction strategies for the sequential go-around prediction problem. Applying these methods to a data set consisting of more than 100,000 flight approaches into JFK airport, we find that the Input Output Hidden Markov Model with multi-step prediction strategy, in general, outperforms other models due to its capability of capturing the inherent temporal structure of the entire flight sequence.

Distributional Equity of Replacing Fuel Taxes with Vehicle Miles Traveled Fees: Evidence from Five San Francisco Bay Area Cities

Thu, 23 Apr 2026 00:00:00 +0000

In a world where people are increasingly shifting from internal combustion engine (ICE) vehicles to electric vehicles, revenue from state fuel taxes has continued to decline. This has prompted policymakers to consider alternative mechanisms to fund transportation infrastructure, including the introduction of a Vehicle Miles Travelled (VMT) fee. However, these changes may have distributional consequences. This study examines the geographical equity impacts of a VMT fee on residents of five cities in the San Francisco Bay Area and compares the financial burdens of a VMT fee and the existing fuel tax for households living in urban and rural settings. Household-level travel, income, and residential location data were obtained from the 2017 National Household Travel Survey. Four scenarios were evaluated: the current fuel tax, a static VMT fee, a dynamic VMT fee with modified elasticities, and a dynamic VMT fee using raw elasticities. Equity was assessed using the Gini Index. Results...

Vehicle Weight Safety Study Academic Report

Mon, 2 Mar 2026 00:00:00 +0000

The Vehicle Weight Safety Study provides supporting analysis for the California Transportation Commission’s study on therelationship between vehicle weight and road user injury and roadway degradation required by Assembly Bill (AB) 251, which was signed by the Governor in October 2023. To inform the work of the CTC, this report summarizes trends of road user injuries and fatalities in California and potential factors contributing to these trends (Chapter 2); summarizes trends in vehicle weight, size, and height for registered vehicles in California (Chapter 3); documents the landscape of policy solutions focused on vehicle size that might address California’s road user injuries and fatality challenge (Chapter 4); analyzes the impact of potential weight-based fees on consumer vehicle purchasing behavior (Chapter 5); and, analyzes the relationship between shifts in passenger vehicle weight and degradation of road infrastructure (Chapter 6).

Electric Vehicle Charge Management Strategies to Benefit the California Electricity Grid

Tue, 11 Mar 2025 00:00:00 +0000

Recent studies suggest that there could be significant value to electric vehicle (EV) drivers and power companies from incorporating EVs into the state’s electrical power grids, known as Vehicle-Grid Integration (VGI). However, the benefits could be highly variable depending on the location of the utility territory, vehicle type and battery capacity, the relevant timeframe, and whether the connection involves only managed charging or includes bidirectional charging permitting vehicle to grid (V2G) power transfer, and other factors. Various studies conducted to date generally conclude that the opportunities for V2G could have two to three times the value of managed (or “smart”) charging. However, there are considerable additional complications for grid integration, including variable and site-specific implementation costs. Some savings such as deferring distribution system upgrades can be very significant but are also site-specific and depend on the level of curren and projected...

Distance-dependent Congestion Pricing for Downtown Zones

Fri, 22 Nov 2024 00:00:00 +0000

A growing literature exploits macroscopic theories of traffic to model congestion pricing policies in downtown zones. This study introduces trip length heterogeneity into this analysis and proposes a usage-based, time-varying congestion toll that alleviates congestion while prioritizing shorter trips. Unlike conventional trip-based tolls the scheme is intended to align the fees paid by drivers with the actual congestion damage they do, and to increase the toll’s benefits as a result. The scheme is intended to maximize the number of people that finish their trips close to their desired times. The usage-based toll is compared to a traditional, trip-based toll which neglects trip length. It is found that, like trip-based tolls, properly designed usage-based tolls alleviate congestion. But they reduce schedule delay more than trip-based tolls and do so with much smaller user fees. As a result usage-based tolls always leave those who pay with a large welfare gain. This may increase...

Economies of Density, Network Size and Spatial Scope in the European Airline Industry

Fri, 22 Nov 2024 00:00:00 +0000

In this article we use four different indices to measure cost performance of the European Airline Industry. By using the number of routes as an indicator of Network Size, we are able to estimate indicators of Economies of Density, Network Size and Spatial Scope. By estimating total and variable cost functions we are also able to calculate an index of the excess capacity of the firms. For this purpose, we use data from the years 1984 to 1998, a period during which several deregulation measures were imposed on the European airline industry. Some of the implications of this deregulation process for the cost performance of the industry are presented and discussed. Our results suggest that in the year 1998, almost all the firms had Economics of Density in their existing networks, while several of the firms also had Economies of Network Size and Economies of Spatial Scope. All of the firms had excess capacity of fixed inputs. These results support our hypothesis...

Conception and Development of the Alameda Corridor

Wed, 3 Jul 2024 00:00:00 +0000

Conception and Development of the Alameda Corridor

Understanding California wildfire evacuee behavior and joint choice making

Wed, 6 Apr 2022 00:00:00 +0000

For evacuations, people must make the critical decision to evacuate or stay followed by a multi-dimensional choice composed of concurrent decisions of their departure time, transportation mode, route, destination, and shelter type. These choices have important impacts on transportation response and evacuation outcomes. While extensive research has been conducted on hurricane evacuation behavior, little is known about wildfire evacuation behavior. To address this critical research gap, particularly related to joint choice-making in wildfires, we surveyed individuals impacted by the 2017 December Southern California Wildfires (n = 226) and the 2018 Carr Wildfire (n = 284). Using these data, we contribute to the literature in two key ways. First, we develop two latent class choice models (LCCMs) to evaluate the factors that influence the decision to evacuate or stay/defend. We find an evacuation keen class and an evacuation reluctant class that are influenced differently by mandatory...

Willingness of Hurricane Irma evacuees to share resources: a multi-modeling approach

Wed, 2 Mar 2022 00:00:00 +0000

Recent technological improvements have greatly expanded the sharing economy (e.g., Airbnb, Lyft, and Uber), coinciding with growing need for transportation and sheltering resources in evacuations. To understand influencers on sharing willingness in evacuations, we employed a multi-modeling approach across four sharing scenarios using three model types: 1) four binary logit models that capture each scenario separately; 2) a multi-choice latent class choice model (LCCM) that jointly estimates multiple scenarios via latent classes; and 3) a portfolio choice model (PCM) that estimates dimensional dependency. We tested our approach by employing online survey data from 2017 Hurricane Irma evacuees (n=368).

The multi-model approach uncovered behavioral nuances undetectable with a single model. First, the multi-choice LCCM and PCM models uncovered scenario correlation, specifically willingness to share for both transportation scenarios and both sheltering scenarios. Second, the...

Flexibility in California Transportation Funding Programs and Implications for More Climate-Aligned Spending

Tue, 1 Feb 2022 00:00:00 +0000

Flexibility in California Transportation Funding Programs and Implications for More Climate-Aligned Spending examines key features of the legislative authority for transportation planning and finance in California, including local option sales taxes for transportation, and assesses the amount of flexibility that current laws and practices allow for reprioritizing projects as problems and priorities change.

MPO Planning and Implementation of State Policy Goals

Mon, 31 Jan 2022 00:00:00 +0000

MPO Planning and Implementation of State Policy Goals evaluates California metropolitan planning organizations’ regional transportation plans and sustainable communities strategies and looks at the relationship between MPO plans and what is actually funded through transportation improvement programs.

Evaluation of California State and Regional Transportation Plans and Their Prospects for Attaining State Goals

Mon, 31 Jan 2022 00:00:00 +0000

Assembly Bill (AB) 285 (Friedman, 2019) requires the California Strategic Growth Council (SGC) to submit a report to the Legislature by January 31, 2022, that includes the following:

An overview of the California Transportation Plan (CTP). An overview of all regional Sustainable Communities Strategies (SCS) and any alternative planning strategies, as needed. An assessment of how the implementation of the CTP and regional plans “will influence the configuration of the statewide integrated multimodal transportation system.” A “review of the potential impacts and opportunities for coordination” of key state funding programs,” to be conducted in consultation with the administering agencies. Recommendations for the improvement of these programs or other relevant transportation funding programs to better align the programs to meet long-term common goals, including the goals outlined in the CTP.

In spring 2021, the SGC contracted with the University of California...

A Brief History of Transportation Policies and Institutions

Mon, 31 Jan 2022 00:00:00 +0000

A Brief History of Transportation Policy and Institutions presents the development of transportation systems in the United States, with particular attention to California. The review includes key technological advances in transportation and the institutions that were developed to implement them. The paper also discusses the problem of organizational inertia and the issues associated with changing organizational culture to better reflect the problems of the day. Review of Statewide Transportation Plans for California reviews the most recently adopted CTP and other key transportation plans adopted by state agencies, discusses the special attention given to new technologies in the CTP, and presents the findings from over 80 interviews with stakeholders across California who were asked to weigh in on the strengths and weaknesses of transportation planning practices in the state.

Examination of Key Transportation Funding Programs in California and Their Context

Mon, 31 Jan 2022 00:00:00 +0000

Examination of Key Transportation Funding Programs in California and Their Context assesses the congruence between funding programs and state goals for transportation. Particular attention is given to major funding sources, such the State Operation and Protection Program, and programs designed to promote key state goals, including the Affordable Housing and Sustainable Communities program, the Transit and Intercity Rail Capital Program, the Transformative Climate Communities program, and the Sustainable Transportation Planning Grant program.

Review of Statewide Transportation Plans for California

Mon, 31 Jan 2022 00:00:00 +0000

California has adopted ambitious goals for its transportation systems. The state has pledged to reduce greenhouse gas(GHG) emissions by 40 percent compared to 1990 levels and by 80 percent by 2050, and has also committed to achieve carbon neutrality by 2045. With transportation a major emitter, substantial changes in transportation vehicles, fuels, operations, and user choices must be achieved to meet these goals. As pressing as climate change goals must be, other goals remain important. California has pledged to maintain its transportation infrastructure in a state of good repair, provide for safe operations, support economic development, meet air quality standards, protect the state’s natural environment, coordinate urban transportation with housing policies, and do so in a way that is equitable for all. This ambitious set of goals places considerable responsibility on transportation planners and decision-makers.

SimUAM: A Comprehensive Microsimulation Toolchain to Evaluate the Impact of Urban Air Mobility in Metropolitan Areas

Wed, 18 Aug 2021 00:00:00 +0000

Over the past several years, Urban Air Mobility (UAM) has galvanized enthusiasm from investors and researchers, marrying expertise in aircraft design, transportation, logistics, artificial intelligence, battery chemistry, and broader policymaking. However, two significant questions remain unexplored: (1) What is the value of UAM in a region’s transportation network?, and (2) How can UAM be effectively deployed to realize and maximize this value to all stakeholders, including riders and local economies? To adequately understand the value proposition of UAM for metropolitan areas, we develop a holistic multi-modal toolchain, SimUAM, to model and simulate UAM and its impacts on travel behavior. This toolchain has several components: (1) MANTA: A fast, high-fidelity regional-scale traffic microsimulator, (2) VertiSim: A granular, discrete-event vertiport and pedestrian, (3) FE³ : A high-fidelity, trajectory-based aerial microsimulation. SimUAM, rooted in granular, GPU-based microsimulation,...

Urban Air Mobility: Viability of Hub-Door and Door-Door Movement by Air

Tue, 24 Mar 2020 00:00:00 +0000

Owing to a century of innovation in connected and automated aircraft design, for the rst time in history, air transport presents a potential competitive alternative to road, for hub-to-door and door-to-door urban services. In this article, we study the viability of air transport, for moving people and goods in an urban area, based on three metrics - enroute travel time, fuel cost and carbon dioxide (CO2) emissions. We estimate the metrics from emission standards and operational assumptions on vehicles based on current market data and compare electric air travel to gasoline road travel. For passenger movement, air is faster than road for all distances. It fares better on fuel cost and emissions only for longer distances (specic transition distances are stated in the text). For consolidated movement of goods, air is at par with road. Finally, for movement of unconsolidated goods, air again fares better than road on all three metrics. It is also noteworthy that these results are...

Role of Trust and Compassion in Willingness to Share Mobility and Sheltering Resources in Evacuations: A Case Study of the 2017 and 2018 California Wildfires

Tue, 11 Feb 2020 00:00:00 +0000

Advances in the sharing economy – such as transportation network companies (e.g., Lyft, Uber) and home sharing (e.g., Airbnb) – have coincided with the increasing need for evacuation resources. While peer-to-peer sharing under normal circumstances often suffers from trust barriers, disaster literature indicates that trust and compassion often increase following disasters, improving recovery through additional resources and support. We hypothesize that trust and compassion could trigger willingness to share transportation and sheltering resources during an evacuation.

Performance Comparison of Crane Double CyclingStrategies

Mon, 10 Feb 2020 00:00:00 +0000

This report compares the performance of three double-cycling algorithms used to determine the sequence with which to load and unload containers from a vessel with a quay crane. Double cycling is a technique which can improve the efficiency of a quay crane and container port by unloading and loading containers in the same crane cycle. The three algorithms, the greedy strategy, the proximal strategy, and Johnson’s rule, are introduced and results from applying the three strategies to a set of simulated vessels are compared. While Johnson’s rule provides the minimum number of cycles required to unload and load a vessel using double cycling, it is operationally less convenient. The proximal strategy is operationally convenient, but provides a smaller benefit when compared to single cycling. All strategies provide significant benefit (about a 40% reduction over single cycling for hatchless ships), and the results are not particularly sensitive to the algorithm used.

User Acceptance and Public Perception Regarding Automated Driving Systems

Fri, 21 Jun 2019 00:00:00 +0000

Fully Automated Driving System (ADS) is one of the most innovative and fundamentally disruptive changes in transportation. This technology has the potential to resolve or mitigate current transportation problems, including reducing traffic accidents, congestion, energy consumption, and pollution. However, the extent of these impacts will depend heavily on public perception and widespread adoption of ADSs. To gain a better understanding of user acceptance and public perception related to ADS, extensive interviews were conducted with Tesla end-users who have experience using partial ADS (i.e., Autopilot) as well as with transportation experts to identify policy gaps related to ADS deployment and adoption. Several focus groups with different stakeholder groups were also organized and an online survey was administered to engage the broader public on these issues. Key findings from this research are presented below and offer insights public agencies can use to develop policy that benefits...

The Producer Surplus Associated with Gasolne Fuel Use in the United States

Mon, 7 Jan 2019 00:00:00 +0000

Estimating the producer surplus – the revenue above the average long-run cost – is an important part of social cost-benefit analyses of changes in petroleum use. This paper estimates the producer surplus associated with changes in gasoline fuel use in the United States, and then applies the estimates of producer surplus to two kinds of social cost-benefit analyses related to petroleum use: (1) estimating the wealth transfer from consumers to producers as a result of policies that affect oil use and oil imports to the US, and (2) comparing the actual average cost of gasoline with the average cost of environmentally superior alternatives to gasoline, such as hydrogen. Our results show that a 50% reduction in gasoline use in the US in 2004 would have saved the US $72 billion in producer surplus payments to foreign oil producers. Applying our estimates to the comparison of the social lifetime cost of hydrogen vehicles versus gasoline vehicles, we find that inconsistently counting...

Intelligent Transportation Systems and Infrastructure A Series of Briefs for Smart Investments

Mon, 11 Dec 2017 00:00:00 +0000

The last decade has witnessed an unprecedented convergence of communication, control, and sensing that can potentially transform transportation infrastructure and delivery. At the most basic level, efficient operation and maintenance of our nation’s transportation infrastructure requires real time data exchange provided by intelligent transportation system technology. When implemented, these technologies have the potential to revolutionize the nation’s economic vitality by moving people and goods more quickly, efficiently, safely, and at lower cost to consumers.

Network Effects in Bus Transit: Evidence from Barcelona’s Nova Xarxa

Fri, 3 Mar 2017 00:00:00 +0000

This paper shows that improving the structure of a bus transit network to facilitate transfers can boost and shape its demand. The idea is illustrated with data from the Nova Xarxa in Barcelona. Deployed in phases, the Nova Xarxa is shown to be attracting more demand than the network it replaces. The paper further shows that this growth is underpinned by transfers -- at the end of 2015, the percentage of trips that involved a transfer was approximately 26%, and it reached a maximum of 57% for line V7. The paper shows these numbers should increase considerably (to 44% and 66%, respectively) once the Nova Xarxa is completed in 2018. This should be compared with the percent of transfers in other existing bus systems, which ranges from 1.3% to 16%.

Dynamic Control of Complex Transit Systems

Mon, 1 Jun 2015 00:00:00 +0000

This paper proposes a dynamic control method to overcome bunching and improve the regularity of fixed-route transit systems. The method uses a combination of dynamic holding and en-route driver guidance to achieve its objectives. It applies to systems with a mix of headway-based and schedule-based lines but it is evaluated for scheduled systems as this is the more challenging application. Improved schedule adherence is the goal. The method’s calculation complexity per piece of advice does not increase with system size. As a result, the method is scalable and can be used with large multiline systems, no matter how complex. When controled, each vehicle is mostly affected by exogenous disturbances (e.g. traffic) and very little by other vehicles. As a result, disruptions to a vehicle or group of vehicles caused by inattentive drivers or control equipment failures remain confined to the vehicles experiencing the problems. The control method effectively quarantines “disease”. The method...

Inclusionary Zoning in a Monocentric City

Mon, 3 Nov 2014 00:00:00 +0000

To show how inclusionary zoning alters development, the author finds the most profitable housing design to build on vacant lots at each location in a monocentric city under different regulatory regimes. Section 1 sets up the model by specifying renter's preferences, geography and building parameters. Section 2 solves the developer's profit-maximization problem at each location under each regime. Finally, in Section 3, a numerical simulation confirms the effects predicted by theory and gives a picture of their magnitude.

Singularities in kinematic wave and variational theories: supershocks, solution properties and some exact solution methods

Fri, 22 Aug 2014 00:00:00 +0000

According to the duality theory of traffic flow any well-posed kinematic wave (KW) and/or variational theory (VT) problem can be solved with the same methods either on the time-space plane or the time vs vehicle number plane. To achieve this symmetry, the model parameters and the boundary data need to be expressed in a form appropriate for each plane. It turns out, however, that when boundary data that are bounded in one plane are transformed for the other, singular points with infinite density (jumps in vehicle number) sometimes arise. These singularities require a new form of weak solution to the PDE's that we call an extended solution. Duality theory indicates that these e-solutions must exist and be unique. The paper characterizes these solutions. It shows that their only added feature is a new type of shock that can contain mass and we call a supershock. Nothing else is required. The evolution laws of these shocks are described. An exact solution method for e-problems with...

Riding First Class: Impacts of Silicon Valley Shuttles on Commute & Residential Location Choice

Wed, 12 Feb 2014 00:00:00 +0000

Employer-provided private shuttles have become a prominent part of the transportation network between San Francisco and Silicon Valley. As the Bay Area plans for transportation investments to meet sustainability goals and accommodate future population and employment growth, an understanding of the role of regional commuter shuttles becomes increasingly important. This study investigates the impacts of private shuttles on commute mode and residential location choice by conducting a travel time comparison and surveying shuttle riders. The authors find that the provision of shuttles and knowledge of shuttle stops influences both commute mode and residential location choice. Shuttles are an attractive option due to their time and cost savings compared to other modes. However, shuttles exacerbate the jobs-housing imbalance by enabling individuals to live farther from work. The extent to which location of shuttle stops influences residential location choice varies from person to person,...

Achieving a Higher Capacity National Airspace System: An Analysis of the Virtual Airspace Modeling and Simulation Project

Tue, 3 Mar 2009 00:00:00 +0000

The Virtual Airspace Modeling and Simulation (VAMS) project developed by the National Aeronautics and Space Administration (NASA) presents a detailed plan for increasing National Airspace System capacity. Interviews with aviation experts regarding the VAMS project led to lessons learned which can inform current modernization plans and processes, as the current system prepares for modernization. According to experts consulted, development should include a small number of project developers who provide periodic opportunities for wide stakeholder feedback; roadmaps should incorporate uncertainly and provide project guidance on a high level; and simulation tools are valuable to modernization efforts, yet assumptions should be documented and their sensitivity understood.

Baseline Evaluation of the Freeway Service Patrol (FSP) I-710 Big-Rig Demonstration Program

Thu, 2 Feb 2006 00:00:00 +0000

Freeway service patrol (FSP) is an incident management measure designed to assist disabled vehicles along congested freeway segments and reduce congestion through quick detection, response, and removal of accidents and other incidents on freeways. A two-year demonstration project has been proposed to extend FSP service to big-rigs and other heavy vehicles along the I-710 freeway. The report describes the work performed and the findings from the preliminary evaluation of the proposed I-710 Big-rig FSP demonstration project. The results show that the proposed FSP big-rig project will be cost-effective. Next steps in the ongoing research include detailed evaluation of the effectiveness of the FSP service based on field measurements throughout the two-year demonstration, and development of operational procedures for implementing big-rig FSP service to other freeway routes.

Development Of System Safety Performance Measures In Support Of The Global Analysis And Information Network