Shengyi Gao | University of California, Davis (original) (raw)

Papers by Shengyi Gao

Transportation Research Record, 2007

11th World Conference on Transport ResearchWorld Conference on Transport Research Society, 2007

This paper describes how a statewide urban growth model for California will be run in iteration w... more This paper describes how a statewide urban growth model for California will be run in iteration with the California statewide travel model in order to evaluate major transportation scenarios, such as freeway widenings and high speed rail. In addition, the paper will evaluate land use policies intended to provide for more affordable housing and for habitat protection. This model provides performance measures for travel, economic welfare and equity, rents paid, energy use, greenhouse gas emissions, vehicular air pollution, and habitat loss. The authors propose a framework for interpreting these data, based on recent advances in the theories of well-being for persons and for nations.

In this paper, we report the preliminary results of the sensitivity test for California Productio... more In this paper, we report the preliminary results of the sensitivity test for California Production, Exchange and Consumption Allocation System (PECAS). The sensitivity test includes three scenarios: PECAS Only, Integrated, and High Travel Cost. The PECAS Only scenario allocates production and consumption at a fixed travel cost from years 2000 to 2020. It shows that the floorspace growth is more affected by general plan than travel cost, and residential floorspace types have higher growth rates in suburb, exurb and rural areas. Additionally, nonresidential (industrial and commercial) floorspace types have higher growth rates in the inner urban areas. The Integrated scenario has a more compact land use pattern than the PECAS Only scenario. Compared with the Integrated scenario, the High Travel Cost scenario leads to more compact use. The results from all three scenarios imply that the model behaves as expected and the outputs are consistent with what has been theorized.

The Institute receives oversight from an internationally respected Board of Trustees whose member... more The Institute receives oversight from an internationally respected Board of Trustees whose members represent all major surface transportation modes. MTI's focus on policy and management resulted from a Board assessment of the industry's unmet needs and led directly to the choice of the San José State University College of Business as the Institute's home. The Board provides policy direction, assists with needs assessment, and connects the Institute and its programs with the international transportation community. MTI's transportation policy work is centered on three primary responsibilities: MINETA TRANSPORTATION INSTITUTE Research MTI works to provide policy-oriented research for all levels of government and the private sector to foster the development of optimum surface transportation systems. Research areas include: transportation security; planning and policy development; interrelationships among transportation, land use, and the environment; transportation finance; and collaborative labormanagement relations. Certified Research Associates conduct the research. Certification requires an advanced degree, generally a Ph.D., a record of academic publications, and professional references. Research projects culminate in a peer-reviewed publication, available both in hardcopy and on TransWeb, the MTI website (http://transweb.sjsu.edu). Education The educational goal of the Institute is to provide graduate-level education to students seeking a career in the development and operation of surface transportation programs. MTI, through San José State University, offers an AACSB-accredited Master of Science in Transportation Management and a graduate Certificate in Transportation Management that serve to prepare the nation's transportation managers for the 21st century. The master's degree is the highest conferred by the California State University system. With the active assistance of the California Department of Transportation, MTI delivers its classes over a state-ofthe-art videoconference network throughout the state of California and via webcasting beyond, allowing working transportation professionals to pursue an advanced degree regardless of their location. To meet the needs of employers seeking a diverse workforce, MTI's education program promotes enrollment to under-represented groups. Information and Technology Transfer MTI promotes the availability of completed research to professional organizations and journals and works to integrate the research findings into the graduate education program. In addition to publishing the studies, the Institute also sponsors symposia to disseminate research results to transportation professionals and encourages Research Associates to present their findings at conferences. The World in Motion, MTI's quarterly newsletter, covers innovation in the Institute's research and education programs. MTI's extensive collection of transportation-related publications is integrated into San José State University's world-class Martin Luther King, Jr. Library. The contents of this report reflect the views of the authors, who are responsible for the facts and accuracy of the information presented herein. This document is disseminated under the sponsorship of the

Urban and regional air pollution is an increasingly critical problem in areas where rapid growth ... more Urban and regional air pollution is an increasingly critical problem in areas where rapid growth is occurring and future development is expected. Within the typical planning horizon, many modeling tools (e.g., land use, travel demand, and emissions models) are used to evaluate the impact of regional development, population trends, and infrastructure improvements on air quality. However, these models were not designed, nor are they generally used as a cohesive system with feedbacks between them. Consequently, there is a gap in our understanding of how different models interact and combine to influence emissions inventories associated with future policy scenarios. In this study, funded by the Environmental Protection Agency, an emissions modeling framework was developed using the UPlan, TP+/Viper, and UCDrive emission models for the San Joaquin Valley (SJV) in central California. Specifically, future land use and subsequent travel patterns and emissions inventories were examined based on four policy scenarios for the year 2030: baseline (following general plans, with no roadway expansion), controlled growth (compact urban boundary, higher residential densities, no roadway expansion), uncontrolled growth (low residential densities, roadway expansion), and as-planned (following general plans, with roadway expansion). The integrated modeling framework links emissions to levels of travel pattern variations under different land use policy and development strategies. For example, compared to a scenario with highly controlled urban growth strategies, less restraint on urban growth results in more than a 20% increase in vehicle miles traveled and about 18% higher emissions of primary pollutants at the regional scale in year 2030. By means of comparing and connecting land use, travel patterns and emissions, the sensitivity of SJV mobile emission inventories to different possible growth scenarios can be assessed.

Transportation Research Record, 2003

We review urban models useful in transportation planning, focusing especially on ones that are ba... more We review urban models useful in transportation planning, focusing especially on ones that are based on geographic information systems (GIS) software. We then describe UPlan, a simple model written by us in the ArcView GIS. Several different applications of UPlan are outlined, involving transportation planning and the analysis of the growthinducing effects of new facilitites, to demonstrate its use. Such models are coming into use for NEPA assessments and for joint land use and transportation planning. I. INTRODUCTION In this paper, we describe a Geographic Information System (GIS)-based urban growth model that runs in the Windows version of ArcView on a personal computer. The model was designed by us to rely on a minimum amount of data, but allocates urban growth in several land use types for small (parcel-sized) grid cells. It is a scenario-testing model that can be applied to any county or metropolitan region and that is transparent to the user, making it easy to change the assumptions for land use allocation. The model is rule-based, that is it is not strictly calibrated on historical data and uses no choice or other statistical models. Projecting the detailed footprint of development with several land use types allows us to then apply various urban impact models, that forecast soil erosion, local service costs, and other impacts. We describe several applications of UPlan. Any state/regional/local transportation agency, citizens group, or county planning department will be able to utilize this model, using generally available datasets. II. BACKGROUND The 1991 Intermodal Surface Transportation Efficiency Act (ISTEA) marked a major turning point in how transportation modeling is conducted. Prior to the Act, transportation planning occurred in somewhat of a vacuum. Travel demand models were run with the same land use inputs for all scenarios, so changes in land uses due to network improvements were not accounted for. The basic concern of most modeling efforts was to simply test how network improvements affected congestion and air quality, overlooking how those improvements influence urban development. Since the enactment of ISTEA, however, transportation agencies have begun to adopt methods that simulate changes in land use, as well as changes in travel. These integrated models, or, more commony, linked transportation and land use models, enable planners to develop a better understanding of how these urban systems interact. Urban models are an improvement over travel demand models of the past, both theoretically and operationally. However, the urban models considered to be the most comprehensive and behaviorally based (land market bidding models) are also very tedious to calibrate and operate. They take 2-3 years to develop the data and calibrate the model and cost $1-2 million. For planning agencies and citizen groups interested only in the land use results of these models, they will likely find them prohibitively complicated and expensive. It is in this context that the geographic information system (GIS)-based land use models are especially useful. TRB 2003 Annual Meeting CD-ROM Paper revised from original submittal. 5. Complex Land Use Models. These can be a land use model that interfaces with an existing travel model, or an integrated urban model with land development and travel models together. These models generally use land prices, and sometimes floorspace lease values, to represent demand for space. They also use accessibility and other factors to represent site attributes. DRAM/EMPAL has been widely used in the U.S. and does not use land value or floorspace lease value data and so is the easiest to implement. TRANUS and MEPLAN have been applied to many regions all over the world and do rely on land market data. A review of complex land use models can be found at Wegener (1994). Another way to categorize land use models is to examine those in use in regional transportation planning agencies. The following table is derived from Miller, Kriger, and Hunt (1998) and updated to 2001. It shows the combinations of land use models and travel models in use or in development in the U.S. It is important to note that most MPOs use the judgement method of land use forecasting and then use this single forecast for all transportation investment scenarios. This is an inaccurate method, in that improvements in radial accessibility will generally increase the spread of land development. Significant additions to road capacity, especially on the edges of congested urban regions, will increase land development in those areas, according to the official study in the U.S. (Expanding Metropolitan Highways 1995). If these land use impacts in the outer areas are not assessed, the NEPA documents will be inaccurate in that the studies will likely bias the projections of travel and emissions downward for highway improvement plans and projects. The secondary effects of land development on habitats, water quality, farmlands, and other systems will also be underprojected. Note that UPlan is in the Connected Land Use Models category, in its application in Sacramento with a travel model, which we describe below. Equilibrium Allocation land use models are a type of model in the Complex Land Development Models category in the FHWA typology and are used in several regions in the U.S. We believe that all MPOs should adopt land development models of some sort. The advantage of taking an overview of these models is so MPOs can see that they can TRB 2003 Annual Meeting CD-ROM Paper revised from original submittal.

Landscape and Urban Planning, Dec 1, 2009

Global human population transitioned from a rural to urban majority in 2008. The struggle to acco... more Global human population transitioned from a rural to urban majority in 2008. The struggle to accommodate urban growth while simultaneously conserving natural resources will be felt around the globe. The capacity to project urban growth scenarios that reflect various public policies so that their relative impacts can be evaluated on natural resources is broadly needed. We developed a framework for such analyses by using a spatially explicit urban growth model to project seven different growth scenarios that represent a range of public policies. The outputs were analyzed in terms of their impacts on 14 types of conservation priority lands. The scenarios covered policies that ranged from "Business as Usual," to "Farmland Soils Protection," to "Compact Growth." At state-government convened meetings, regional scientists identified and assembled the 14 key conservation priority data layers reflecting high value open space and conservation opportunities. We assessed the impact of each projected urban growth output with each conservation priority layer. The scenario with the least overall ecological impact was the Compact Growth Scenario; the Great Cities Scenario was also relatively low. Because of its efficiency and ease of use, the general availability of needed data, and its suitability for use by local governments, the method presented here could be incorporated for other regions of the world where working landscapes are negatively affected by urban growth.

RePEc: Research Papers in Economics, Aug 1, 2006

One-foot resolution imagery is used to develop a detailed land cover map for part of Highway 99 i... more One-foot resolution imagery is used to develop a detailed land cover map for part of Highway 99 in the San Joaquin Valley of California, US. The land cover map is used to model the probability of occurrence of 12 endangered or threatened species and as input to an urban growth model to examine the likelihood of development of every map unit. The combination of the two model predictions permits the categorization of every map unit with a potential endangered species richness index and predicted degree of development. Polygons with high potential endangered species richness were ranked according to the degree of development pressure. This planning approach is computationally intensive, but the input data are relatively easy to assemble, consisting of: a detailed, and fine-scale, land cover map; species presence locations; statewide climate and landcover maps; a parcel ownership map; population growth projections; and a digital map of the county general plan.

RePEc: Research Papers in Economics, 2007

RePEc: Research Papers in Economics, Apr 1, 2008

The Sacramento, California region is engaged in an innovative long-range visioning process during... more The Sacramento, California region is engaged in an innovative long-range visioning process during 2004 and 2005, where the regional transportation planning agency is defining and modeling several 50-year growth scenarios. We worked with environmental and social equity citizens groups to define policies that would reduce emissions, serve lower-income travelers better, and preserve habitats and agricultural lands in the region. The citizens groups rejected the new freeways planned for the region, as well as the substantial freeway widenings for HOV lanes. In addition, they defined a more-ambitious transit system, involving new Bus Rapid Transit lines and shorter headways for all rail and bus service. This transit-only plan was modeled, by itself, and along with a land use policy for an urban growth boundary and a pricing policy for higher fuel taxes and parking charges for worktrips. We used a new version of the MEPLAN model to simulate these scenarios over 50 years and describe our findings regarding total travel, mode shares, congestion, emissions, land use changes, and economic welfare of travelers.

Transportation Research Record, 2005

eScholarship provides open access, scholarly publishing services to the University of California ... more eScholarship provides open access, scholarly publishing services to the University of California and delivers a dynamic research platform to scholars worldwide.

Transportation Research Record, 2009

inner city and have low car ownership, while most entry-level jobs for which welfare recipients a... more inner city and have low car ownership, while most entry-level jobs for which welfare recipients are qualified are in the suburbs. The welfare recipients and entry-level jobs are spatially mismatched. Insufficient transit service and low access to private automobiles make it difficult for welfare recipients to commute between the inner city and suburbs. Empirical studies (8-10) have demonstrated that the larger the city, the worse the transportation barrier is. Thus, the common policy recommendations are to improve transit to overcome the spatial separation between the residences of welfare recipients and entry-level jobs or to enhance car ownership among the welfare recipients, or both. Although there is a debate about the role of transit in moving welfare recipients to self-sufficiency (3, 11), both approaches are adopted in practice. Important planning questions arise concerning the two approaches. First, to what extent will they affect regional job accessibility, specifically the job accessibility of households who heavily rely on transit? Second, to what extent is the level of service of the highway network affected by the application of the two approaches? Third, how are traveler benefits redistributed among households in different income classes? Because the two policies focus on welfare recipients, it is expected that a successful policy will mean that welfare recipients (low-income households) will have larger percentage gains in traveler benefits than households with higher incomes and that the performance of the transportation system will not be negatively affected. To address these policy evaluation questions, this study makes use of the travel demand forecast model adopted by the Sacramento Area Council of Governments (SACOG) to simulate the impacts of enhancing car ownership and of improving fixed-route transit. LITERATURE REVIEW The physical separation of entry-level jobs and the people who need the jobs captured sociologists' attention in the 1960s. Kain (12) proposed the spatial mismatch hypothesis to address the relationship between employment rate and residence. His research initiated a large volume of studies on the impacts of job accessibility on employment for central-city households. Some studies (13-18) provided supportive evidence for this hypothesis. Recently, many researchers have tested whether spatial mismatch exists for welfare recipients. Sawichi and Moody (10) documented the residence locations of welfare recipients and the locations of entry-level jobs in the Atlanta, Georgia, area, where the majority of entry-level jobs were in the northern suburbs, while welfare clients mainly resided in the inner city. The welfare recipients had low access to the entry-level

The California statewide integrated land use and transportation modeling has being developed usin... more The California statewide integrated land use and transportation modeling has being developed using the PECAS framework. This paper focus on two goals: a) presenting a framework for identifying household lifestyle clusters, and b) applying them to a spatial economic model system. A household's lifestyle is defined by two sets of dimensions: space use and household wage. Using a two-step clustering algorithm, different household lifestyle clusters were identified. The applicability of these lifestyle clusters for a integrated land use and transportation model was explored.

In this study, the authors discussed the advantages of using behavior based travel impedance at d... more In this study, the authors discussed the advantages of using behavior based travel impedance at disaggregate level and gravity factors in destination choice for non-commute trips, and empirically demonstrate how these variables improve the destination choice model. The authors found that 1) the time impedance based on individual behavior is a determinant of destination choice for non-commute trips. Travelers prefer closer locations to where they live; 2) the gravity factors (including zone size and trip length) have a significant impact on destination choice behavior. The zones with high gravity are more likely to be chosen as the destinations. The Zone Size, has a positive impact on destination choice while the distance lowers the utility of destination choice and has a negative impact on destination choice; 3) people with higher income travels farther; 4) younger people travels farther.

Annals of Regional Science, Aug 18, 2007

Using structural equation modeling, this study empirically examines the connections between job a... more Using structural equation modeling, this study empirically examines the connections between job accessibility, workers per capita, income per capita, and autos per capita at the aggregate level with year 2000 census tract data in Sacramento County, CA. Under the specification of the conceptual model, the model implied covariance matrix exhibits a reasonably good fit to the observed covariance matrix. The direct and total effects are largely consistent with theory and/or with empirical observations across a variety of geographic contexts. It is demonstrated that structural equation modeling is a powerful tool for capturing the endogeneity among job accessibility, employment, income, and auto ownership.

development, growth-inducing impacts

Using census block groups data on socio-demographics, land use, and travel behavior, we test the ... more Using census block groups data on socio-demographics, land use, and travel behavior, we test the cutoffs suggested in the literature for trustworthy estimates and hypothesis testing statistics, and evaluate the efficacy of deleting observations as an approach to improving multivariate normality, in structural equation modeling. The results show that the measures of univariate and multivariate non-normalities will fall into the acceptable ranges for trustworthy maximum likelihood estimation after a few true outliers are deleted. We argue that pursuing a multivariate normal distribution by deleting observations should be balanced against loss of model power in the interpretation of the results. Non-normality of Data in Structural Equation Models Shengyi Gao Dept. of Environmental Science and Policy University of California One Shields Ave. Davis, CA 95616 sgao@ucdavis.edu Phone: (530) 752-6303 Fax: (530)752-3350 Patricia L. Mokhtarian Dept. of Civil and Environmental Engineering Unive...

In this study, authors use a structural equation modeling approach to test the impacts of leisure... more In this study, authors use a structural equation modeling approach to test the impacts of leisure purpose and environmental factors on the elders’ leisure features, location choice, and related travel behavior. The results showed that leisure purpose had significant direct impacts on leisure features and locations but had no direct effects on leisure related travel behavior. Environmental factors had only direct effects on leisure locations and indirect effects on leisure related travel behavior. The results suggest that community parks and neighborhood green fields were more important to the elders’ leisure activities than large city parks due to high proximity and thus should be deliberately planned to improve the elders’ well-being in urban land use development.