working paper

Charge It: The Promise of Plug-in Electric Hybrids

Publication Date

June 30, 2010

Author(s)

Will Recker, Jee Eun (Jamie) Kang

Areas of Expertise

Zero-Emission Vehicles & Low-Carbon Fuels

View working paper

Abstract

This study found that plug-in hybrids can significantly reduce emissions and energy consumption in urban settings where average trip distances are fairly short. The ability of plug-in hybrids to deliver environmental benefits will rely heavily on initiatives that reduce charging times and provide wider opportunities for charging outside the home. in this regard, we recommend enacting policies that 1) encourage affordable conversion from 120-volt to 240-volt charging at home and 2) provide for installation of 240-volt charging facilities at public and private parking facilities adjacent to major activity centers, like shopping malls and rail transit stations.

Phd Dissertation

Mediating change and changes in mediation adapting ICTs for just environmental governance

Publication Date

June 29, 2010

Author(s)

C. Smith

Areas of Expertise

Intelligent Transportation Systems, Emerging Technologies, & Big Data Travel Behavior, Land Use, & the Built Environment

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Abstract

Information and communication technologies (ICTs) are important research areas for scientists examining theories of communication, conflict resolution and collaborative decision-making, particularly because they offer impressive analytical capabilities and the capacity to integrate different modes of deliberation and forms of content. The exponential growth in the adoption and diffusion of these digital media currently has, and will likely continue to have, considerable social ecological implications in part because ICTs are increasingly positioned as places of convergence for politically contested information and knowledge. However, the nature of these implications, especially questions concerning how these technologies influence or mediate changes in policy and/or the policymaking process itself is unclear and controversial. Technological enthusiasts, for example, argue that ICTs have potential to upgrade democracy by improving the way we devise means to clarified ends whereas technological pessimists challenge that, far from ushering in a new age of democracy, new media technologies actually hinder coordinative action by reducing more personalized modes of communication. This research examined both face-to-face and online communication facilitated by three institutions in California–the South Coast Air Quality Management District (SCAQMD), the California Environmental Justice Action Committee (CEJAC) and Communities for a Better Environment (CBE)–as they sought to reach decisions concerning a series of environmental justice-related issues. Informed by a mixed methodological approach, this research characterizes the challenges and opportunities afforded by the traditional face-to-face (F2F) settings hosted by the three organizations (i.e., public hearings, public meetings and workshops, respectively) and communication within these settings differed from and integrated with EJ communication in the institutions’ corresponding new media or ICT-based environments (i.e., general content websites and interactive mapping applications). The research found that, while there were obvious limitations to F2F participation, the pragmatic modes of communication that took place in these three settings were not replicated in the online environment. Most troublesome was that ICT-based communication tended to be less trustworthy, interactive and coherent than corresponding communication in F2F settings. The dissertation concludes by putting forth an alternative ICT-based framework for just environmental governance that enables interdependent, multi-directional and adaptive forms of knowledge production and decision-making.

Phd Dissertation

Development of a spatially and temporally resolved planning tool for deployment of hydrogen infrastructure

Publication Date

June 29, 2010

Author(s)

Shane Stephens-Romero

Areas of Expertise

Infrastructure Delivery, Operations, & Resilience Zero-Emission Vehicles & Low-Carbon Fuels

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Abstract

While the world relies on the combustion of petroleum based fuels to power more than 90% of its transportation, three principal forcing functions are creating a the need to transition to alternative transportation fuels: (1) The impact of anthropogenic greenhouse gas emissions on the global climate; (2) urban air pollution; and (3) energy security. It is increasingly recognized that meeting future greenhouse gas (GHG) reduction, air quality, and energy security goals will require that the future transportation mix include hydrogen in fuel cell electric vehicles (FCEVs). Transitioning to alternatives like hydrogen will require business and policy leaders to invest in new infrastructure cognizant of future energy and environment goals. An advanced planning methodology can play a vital role in this process by delineating the impacts of fully built-out infrastructure scenarios relative to long-term environment and energy security goals, and facilitating the identification of preferred infrastructure roll-out scenarios, thus targeting investments to where they will be most effective. Until now an integrated planning capability for the deployment of alternative transportation fuels has not been available. This research develops and demonstrates the utility of such a planning tool with a focus on hydrogen as a transportation fuel. The tool is then exercised to show that: *A transition to a fully built-out hydrogen infrastructure scenario leads to significant improvements in urban air quality. Reductions in peak 8-hour average ozone and 24-hour PM2.5 of 10% and 15% respectively are observed. *Greenhouse gas reductions on the order 63% compared to gasoline internal combustion engine of are observed for hydrogen infrastructure scenarios where FCEVs reach a 75% share of passenger vehicles. *Compared to the number of existing gasoline stations, a fraction of the number of hydrogen fueling stations (12 – 15%) can provide a similar level of accessibility for drivers in a specific city used as an example. Community statistics inform the rollout order for hydrogen fueling stations. *Systematic planning optimizes both the economic and environmental impact of hydrogen infrastructure by targeting investments to where they will be most effective in meeting renewable hydrogen standards and providing customer accessibility to hydrogen fueling stations.

Phd Dissertation

Comprehensive Assessment of Managed Lane Performance and Characteristic

Publication Date

May 18, 2010

Author(s)

Chih-Lin (Albert) Chung

Areas of Expertise

Infrastructure Delivery, Operations, & Resilience

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Abstract

Managed lanes, specifically for high occupancy vehicle (HOV) and high occupancy and toll (HOT) lanes, face such undiscovered issues as their performance regarding speed dispersion, equilibrium relationships with general purpose (GP) lanes in terms of speed and level of service, and joint effects of managed lane policies like eligibility, access control, and pricing. The goal of this dissertation is to provide theoretical and practical procedures of managed lane operation assessment under four modules. The first module correlates speed dispersion with the fundamental traffic flow parameters. It reveals that coefficients of variation of speed for HOV and GP lanes are exponential with occupancy, negative exponential with space mean speed, and two-phase linear to flow. The second module proposes two speed equilibrium schemes for HOV and GP lanes. The schemes present distinct speed pairs by congestion level, but speed of HOV lanes is identically ensured no less than GP lanes. The second module also develops an HOT scheme that adopts value of time and value of reliability to formulate HOT tolls with respect to speed of GP lanes. The third module identifies lane management and congestion hot spots by contrasting the level of service of managed lanes and GP lanes in deterministic and stochastic ways. The case study indicates that lane management hot spots are spatially and temporally dynamic, and a non-hot spot less likely turns to congestion without being a lane management hot spot as transition, or vise versa. The last module develops two macroscopic approaches to screening the policy combination set of managed lanes. The optimal/non-inferior policies for non-eliminated combinations are verified by multi-objective binary integer linear programming.

Phd Dissertation

An Adaptive Control Algorithm for Traffic-Actuated Signalized Networks

Publication Date

June 2, 2010

Author(s)

Xing Zheng

Areas of Expertise

Infrastructure Delivery, Operations, & Resilience Intelligent Transportation Systems, Emerging Technologies, & Big Data

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Abstract

With advances in computation and sensing, real-time adaptive control has become an increasingly attractive option for improving the operational efficiency at signalized intersections. The great advantage of adaptive signal controllers is that the cycle length, phase splits and even phase sequence can be changed to satisfy current traffic demand patterns to a maximum degree, not confined by preset limits. To some extent, traffic-actuated controllers are themselves “adaptive” in view of their ability to vary control outcomes in response to real-time vehicle registrations at loop detectors, but this adaptability is restricted by a set of predefined, fixed control parameters that are not adaptive to current conditions. To achieve the functionality of truly adaptive controllers, a set of online optimized phasing and timing parameters are needed. This dissertation proposes a real-time, on-line control algorithm that aims to maintain the adaptive functionality of actuated controllers while improving the performance of signalized networks under traffic-actuated control. To facilitate deployment of the control, this algorithm is developed based on the timing protocol of the standard NEMA eight-phase full-actuated dual-ring controller. In formulating the optimal control problem, a flow prediction model is developed to estimate future vehicle arrivals at the target intersection, the traffic condition at the target intersection is described as “over-saturated” throughout the timing process, i.e., in the sense that a multi-server queuing system is continually occupied, and the optimization objective is specified as the minimization of total cumulative vehicle queue as an equivalent to minimizing total intersection control delay. According to the implicit timing features of actuated control, a modified rolling horizon scheme is devised to optimize four basic control parameters–phase sequence, minimum green, unit extension and maximum green–based on the future flow estimations, and these optimized parameters serve as available signal timing data for further optimizations. This dynamically recursive optimization procedure properly reflects the functionality of truly adaptive controllers. Microscopic simulation is used to test and evaluate the proposed control algorithm in a calibrated network consisting of thirty-eight actuated signals. Simulation results indicate that the proposed algorithm has the potential to improve the performance of the signalized network under the condition of different traffic demand levels.

working paper

Commercial Motor Vehicles' Safety - A California Perspective

Publication Date

April 30, 2010

Author(s)

Gen Giuliano

Areas of Expertise

Freight, Logistics, & Supply Chain Safety, Public Health, & Mobility Justice

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Abstract

This report presents the findings of an examination of commercial motor vehicle crashes in California. Initially, a review of the basic descriptive statistics associated with truck-involved crashes in California was conducted; it covered the time period between January 1995 and December 2004 based on the Statewide Incident Tracking and Reporting System (SWITRS) data base, which contains information about every single motor vehicle accident in the state reported to a law enforcement agency. In addition to examinations of the entire population of truck-involved crashes in the state over the designated period, truck-involved crashes in Los Angeles County and the San Francisco Bay Area were also investigated. The next part of the report investigated the rates of truck accidents across California to determine the risk factors involved, including exposure to truck crashes, environmental conditions and demographic factors. The investigation involves modeling crashes as a function of these risk factors based on SWITRS data between 1998 and 2004.

research report

CARTESIUS and CTNET - Integration and Field Operational Test: Year 2

Publication Date

April 30, 2010

Associated Project

Cartesius and CTNET – Integration and Field Operational Test

Author(s)

Michael McNally, Craig Rindt

Areas of Expertise

Infrastructure Delivery, Operations, & Resilience Intelligent Transportation Systems, Emerging Technologies, & Big Data

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Abstract

This report describes the conclusion of PATH Task Order 6324: CARTESIUS and CTNET—Field Operational Test. We describe the results of the multi-year project focused on integrating Caltrans primary signal management system, CTNET, with a major product from the Caltrans ATMS Testbed: the Coordinated Adaptive Real-Time Expert System for Incident management in Urban Systems, or more simply, CARTESIUS. The major products of this research include numerous software products for integrating CTNET with field devices, simulation software, with other traffic management systems in general, and with a streamlined re-implementation of the CARTESIUS incident management system. The report details the development of the various software components necessary for external systems with CTNET using both the AB3418e protocol and Tent’s own custom socket-based communications protocol for communications between CTNET clients and the CTNET Commerce. The use of these software components to link CTNET to various systems is described, including a non-standard field infrastructure, the Paramics microsimulation, and the CARTESIUS incident management system. The resulting system is used to evaluate a more deployable re-implementation of CARTESIUS connected to the simulation via CTNET. The results of the evaluation demonstrate that the reimplementation produces performance similar to the original system for a restricted evaluation subset. Further work is necessary to lead to complete deployment, particularly defining requirements that are compatible with existing TMC processes. Nonetheless, the work described in this project represents a step toward a deployable next generation architecture for multi-jurisdictional incident management using existing Caltrans assets.

Related Publications

research report | February 03, 2025

CARTESIUS and CTNET Integration and Field Operational Test: Year 1

Phd Dissertation

Flexible Management of Transportation Networks under Uncertainty

Publication Date

March 4, 2010

Associated Project

Large Scale Real Options Models for Network Investment Planning & Operational Risk Hedging

Author(s)

Joseph Chow

Areas of Expertise

Infrastructure Delivery, Operations, & Resilience Intelligent Transportation Systems, Emerging Technologies, & Big Data

View Phd Dissertation

Abstract

Strategies, models, and algorithms facilitating such models are explored to provide transportation network managers and planners with more flexibility under uncertainty. Network design problems with non-stationary stochastic OD demand are formulated as real option investment problems and dynamic programming solution methodologies are used to obtain the value of flexibility to defer and re-design a network. The design premium is shown to reflect the opportunity cost of committing to a “preferred alternative” in transportation planning. Both network option and link option design problems are proposed with solution algorithms and tested on the classical Sioux Falls, SD network. Results indicate that allowing individual links to be deferred can have significant option value. A resource relocation model using non-stationary stochastic variables as chance constraints is proposed. The model is applied to air tanker relocation for initial attack of wildfires in California, and results show that the flexibility to switch locations with non-stationary stochastic variables providing 3-day or 7-day forecasts is more cost-effective than relocations without forecasting. Due to the computational costs of these more complex network models, a faster converging heuristic based on radial basis functions is evaluated for continuous network design problems for the Anaheim, CA network with a 31-dimensional decision variable. The algorithm is further modified and then proven to converge for multi-objective problems. Compared to other popular multi-objective solution algorithms in the literature such as the genetic algorithm, the proposed multi-objective radial basis function algorithm is shown to be most effective. The algorithm is applied to a flexible robust toll pricing problem, where toll pricing is proposed as a strategy to manage network robustness over multiple regimes of link capacity uncertainty. A link degradation simulation model is proposed that uses multivariate Bernoulli random variables to simulate correlated link failures. The solution to a multi-objective mean-variance toll pricing problem is obtained for the Sioux Falls network under low and high probability seasons, showing that the flexibility to adapt the Pareto set of toll solutions to changes in regime – e.g. hurricane seasons, security threat levels, etc – can increase value in terms of an epsilon indicator.

Related Publications

published journal article | February 03, 2025

Network-based real option models

working paper

On-Ramp Metering and Commuter Delay: A Before and After Study

Publication Date

February 28, 2010

Author(s)

Kwang (Kane) Kim

Areas of Expertise

Infrastructure Delivery, Operations, & Resilience

View working paper

Abstract

This report furnishes clear evidence that on-ramp metering can increase the output flow through a freeway, and by so doing diminish the total time that commuters collectively spend traveling on the freeway and its on-ramps. Empirical study was performed on a 6.3-mile stretch of northbound Interstate 5 in Sacramento. The stretch spans the interchanges of Pocket Road (to the south) to W street (See Figure 1). Traffic data, both from loop detectors and from videos, were collected during the morning rush periods over a period spanning several years. Data were initially collected in 2006 prior to the deployment of ramp meters at the site. Data were collected again in 2007 and 2008 after meters were installed on five on-ramps. (The meters operate using a control logic developed by Caltrans.) Finally, a metering logic was developed in response to certain traffic details observed at the site, and was tested there in spring and fall 2009. A number of interesting and useful findings resulted from all this, as described below.

Phd Dissertation

Unraveling the Complexity of Land Use and Travel Behavior Relationships: A Four-Part Quantitative Case Study of the South Bay Area of Los Angeles

Publication Date

September 14, 2009

Associated Project

Accessibility, Travel Behavior, and New Urbanism: Comparative Study of Mixed Use Centers and Auto-Oriented Corridors in the South Bay (Los Angeles) Region

Author(s)

Kenneth Joh

Areas of Expertise

Travel Behavior, Land Use, & the Built Environment

View Phd Dissertation

Abstract

Characteristics of the built environment, such as the mixture of land uses, transportation infrastructure, and neighborhood design, have often been associated with reduced automobile use and increased walking and transit use. However, a significant gap remains in our understanding of travel behavior, especially with respect with social environmental and attitudinal factors influencing travel, such as crime rates and the perceptions of walking. This dissertation, comprised of four empirical essays, explores the complex relationships between the built and social environment and neighborhood travel by focusing on non-work travel for individuals sampled from eight communities in the South Bay Area of Los Angeles County. In the first essay, I examine claims made by proponents of New Urbanism that traditional neighborhood designs promote walking and discourage driving by comparing automobile and walking trip rates for mixed-use centers and auto-oriented corridors. The results showed no discernible differences in individual driving trips between these two types of neighborhoods while more walking trips were reported in mixed-use centers. Therefore, the results both support and challenge New Urbanist claims. The second essay examines the interactions between race/ethnicity, demographic change, and travel behavior by comparing driving and walking trips across racial and ethnic groups. The results showed that African-Americans took fewer driving trips and Asians walked less compared to non-Hispanic whites, and that Hispanics who walk are more sensitive to demographic changes in their neighborhood than other groups. The third essay focuses on crime and perceptions of safety and how they impact walking behavior. After taking sociodemographic and built environment factors into account, violent crime rates had a strong deterrent effect on walking across race, income, and gender groups, while perceptions of neighborhood safety varied. In the fourth essay, I focus on whether the built environment encourages walking above and beyond individuals’ attitudes toward walking. By comparing individuals with positive attitudes toward walking with those with neutral or negative attitudes, the results showed that individuals with positive attitudes were more responsive to built environment characteristics than those held negative attitudes. These findings suggest differences in walking behavior are more strongly shaped by personal attitudes than the built environment.