Transportation

Moeckel, Rolf, Donnelly, Rick

Gradual Rasterization: Redefining the spatial resolution in transport modeling

Finding the appropriate spatial resolution in modeling is a serious challenge at the beginning of every modeling project. The paper presents a methodology to adjust the spatial geography to the resolution of a network. Based on the quadtree algorithm, raster cells are generated that are dynamic in size. Smaller raster cells are used in urban areas and larger raster cells are used in low-density, rural areas. Trip tables of a travel demand model for the State of Georgia are disaggregated to this new zone system of raster cells, and assignment results validate significantly better than when using the original zone system.

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Elijah Knaap, Chengri Ding, Yi Niu, Sabyasachee Mishra

Polycentrism as a Sustainable Development Strategy

We present in this paper an analysis of economic centers and their role in shaping employment development patterns and travel behavior in the state of Maryland. We begin by identifying 23 economic centers in the Baltimore-Washington region. We then examine these centers first in their role as centers of economic activity then in their role as nodes in the state’s transportation system. Finally, we identify the commute sheds of each center, for multiple modes of travel and travel times, and examine jobs-housing balance within these various commute sheds. We find that Maryland’s economic centers not only promote agglomerative economies and thus facilitate economic growth; they also generate a disproportionate number of trips and promote transit ridership. These results provide empirical support for policies that promote polycentric urban development, and especially policies that promote polycentric employment development. Further, they suggest that polycentrism as a sustainable development strategy requires careful coordination of regional transportation systems designed to balance jobs and housing within a center’s transit commute shed. Based on these findings we recommend that the Maryland state development plan and regional sustainable communities’ plans across the nation should encourage the concentration of employment within economic centers and encourage housing development within the transit commute sheds of those centers.

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Chengri Ding

Transportation Development, Regional Concentration and Economic Growth

“New Geographic Economy” suggests an inverted-U shaped relationship between transport costs and regional economic concentration.  By using data on Chinese prefectures, this paper examines the relationship between transportation development and economic concentration, to investigate the “point effect” and “network effect” of transportation stocks and to gauge their relative magnitudes.  The paper concludes the followings: (1) development of urban roads leads to rising GDP shares in the city proper for both manufacturing and service industries.  Major regional roads have the same effect; (2) “point effect” is found for both urban roads and major regional roads in GDPs; (3) there are spillover effects for both urban roads and major regional roads; and (4) different types of transportation infrastructure have different economic impacts.  The policy implication is that the urban-rural economic growth gap likely continues to increase with urban and regional transportation development during the rapid urbanization concurrently undertaken. 

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Fred Ducca, Rolf Moeckel, Sabyasachee Mishra, and Tara Weidner (2012)

A Mega-region Framework for Analyzing a High Energy Price Future

Mega-regions are a new geography that may well form the “nation's operative regions when competing in the future global economy. A challenge is to determine how to foster greater efficiencies in these mega-regions by creating a stronger infrastructure and technology backbone in the Nation's surface transportation system,” according to the March 2010 FHWA Strategic Plan. To meet this challenge these regions will need analysis tools to evaluate scenarios and their regional impacts, analysis tools covering areas larger than covered by the typical Metropolitan Planning Organization (MPO) or State Department of Transportation (DOT) models. This paper describes what makes mega-regions different and identifies analytic issues mega-regions may need to address, identifies the Chesapeake Mega-region and provides a framework for analyzing issues within the Chesapeake mega-region. Finally, the framework is tested through a proof of concept scenario which assumes a sudden price rise in gasoline prices and the likely effects on travel. A brief summary of further work and additional scenarios planned is provided.

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Charles Rivasplata, Hiroyuki Iseki, and Adam Smith (2012)

Transit Coordination in the U.S.: A Survey of Current Practice

As cities expand and travel patterns become more complex, transit passengers are becoming increasingly dependent on multiple systems to satisfy their daily travel needs. To facilitate seamless travel, comprehensive service planning, design, and operation are essential. In some cases, regional entities have integrated routes, timetables, and ticketing based on a common set of planning, investment, and marketing principles. The authors administered a nationwide survey of transit operators to explore the following areas of integration: fare policy/media, service scheduling, information coordination, facility and vehicle coordination, and interagency agreements. According to survey results, the nature and extent of integration varied by size of region and type of integration. Respondents identified challenges to coordination, including financial and political commitment. Furthermore, for integration to be successful, regional and local transport entities must work together to ensure that service providers participate in coordinative strategies, balancing the interests and needs of passengers, operators, and residents.

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Sabyasachee Mishra, Timothy Welch, and Manoj K. Jha (2012)

Performance Indicators for Public Transit Connectivity in Multi-Modal Transportation Networks

Connectivity plays a crucial role as agencies at the federal and state level focus on expanding the public transit system to meet the demands of a multimodal transportation system. Transit agencies have a need to explore mechanisms to improve connectivity by improving transit service. This requires a systemic approach to develop measures that can prioritize the allocation of funding to locations that provide greater connectivity, or in some cases direct funding towards underperforming areas. The concept of connectivity is well documented in social network literature and to some extent, transportation engineering literature. However, connectivity measures have limited capability to analyze multi-modal public transportation systems which are much more complex in nature than highway networks.

In this paper, we propose measures to determine connectivity from a graph theoretical approach for all levels of transit service coverage integrating routes, schedules, socio-economic, demographic and spatial activity patterns. The objective of using connectivity as an indicator is to quantify and evaluate transit service in terms of prioritizing transit locations for funding; providing service delivery strategies, especially for areas with large multi-jurisdictional, multi-modal transit networks; providing an indicator of multi-level transit capacity for planning purposes; assessing the effectiveness and efficiency for node/stop prioritization; and making a user friendly tool to determine locations with highest connectivity while choosing transit as a mode of travel. An example problem shows how the graph theoretical approach can be used as a tool to incorporate transit specific variables in the indicator formulations and compares the advantage of the proposed approach compared to its previous counterparts. Then the proposed framework is applied to the comprehensive transit network in the Washington-Baltimore region. The proposed analysis offers reliable indicators that can be used as tools for determining the transit connectivity of a multimodal transportation network. 

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Sabyasachee Mishra and Timothy Welch (2012)

A Joint Travel Demand and Environmental Model To Incorporate Emission Pricing For Large Transportation Networks

Emission reduction strategies are gaining greater attention to support the national objective for a sustainable and green transportation system. A large percent of emission contribution that arises from transportation modes are primarily from auto and truck travel. Reductions in highway travel require prudent planning strategies and modeling user’s response to planner’s policies. Modeling planning goals and user’s response is a challenging task. In this paper the authors present a joint travel demand and environmental model to incorporate vehicle emission pricing (VEP) as a strategy for emission reduction. First, the travel demand model determines the destination, mode and route choice of the users in response to the VEP strategy set by the planner. Second, the emission model provides NOx, VOC, and CO2 estimates at a very detailed level. A Base-case and three models are proposed to incorporate VEP in a multimodal transportation network. The objective function of the Base-case is the minimization of Total System Travel Time (TST), and the models are designed with the objective of minimizing Total System Emission (TSE). User Equilibrium method is used for travel to model user responses and solved by Frank Wolfe algorithm. The Base-case represents “do-nothing” conditions and the three models address the interactions between planner’s perspectives and user responses to VEP strategies. The proposed model is applied to Montgomery County’s (located in the Washington DC-Baltimore region) multimodal transportation network. The case study results show that VEP can be used as a tool for emission reduction in transportation planning and policy.

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Sabyasachee Mishra and Snehamay Khasnabis (2012)

An Optimization Model for Allocating Resources for Highway Safety Improvement at Urban Intersections

The authors present a procedure for allocating resources for implementing safety improvement alternatives at urban intersections over a multi-year planning horizon. The procedure, based upon optimization techniques, attempts to maximize benefits-measured in dollars saved by reducing crashes of different severity categories, subject to budgetary and other constraints. It is presented in two parts (1) a Base case including the objective function and a set of mandatory constraints, and (2) additional policy constraints / special features that can be separately incorporated to the Base case.

Demonstration of the procedure is presented on intersections in the Detroit metropolitan region, where economic losses resulting from traffic crashes at intersections are estimated to exceed $4 billion annually. The proposed model can allocate resources for safety improvement alternatives over a planning horizon, given a number of independent locations and a number of mutually exclusive alternatives at each location. The policy constraints provide the analyst the flexibility of adding equity, urgency, and other features to the Base case. Integer programming technique is applied to solve the demonstration problem. 

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Snehamay Khasnabis, Sabyasachee Mishra, and Chirag Safi (2012)

An Evaluation Procedure for Mutually Exclusive Highway Safety Alternatives under Different Program Missions

The purpose of evaluating mutually exclusive alternatives is to select the one with the highest benefits for implementation. A number of analytic techniques are available for such evaluation purposes. Four such techniques: Cost Effectiveness (C/E), Benefit Cost Ratio (B/C), Internal Rate of Return (IRR), and Pay-off Period (PP) are discussed in this paper, including their theoretical foundation and data requirements, Also discussed are the measures of effectiveness (MOE) associated with each of these techniques, and how these are to be interpreted.

Alternatives to be selected for implementation following such evaluation can typically be funded under different policy objectives. Three such objectives are identified in the paper: Objective A, constrained resource perspective; Objective B, investment perspective; and Objective C, face value perspective. The possible relationship between the alternative selection and program is discussed in the paper. A case study for a set of six mutually exclusive highway safety alternatives is presented using the four analytic techniques and three objectives, resulting in various possible solutions. 

Results show that under compatible assumptions, and for a given policy objective, the outcome of the evaluation is not affected by the choice of the analytic technique. However, for a given analytic technique, the outcome may be affected by the choice of the policy objective chosen. The principles presented are relevant for most public projects (e.g. transit, airports, etc.) involving the investment of taxpayer resources, even though the case study involves a highway safety project. 

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Sabyasachee Mishra, Snehamay Khasnabis, and Sunder Lall Dhingra (2012)

A Simulation Approach for Modeling Risk in Transportation Infrastructure Investment Decision Making

Traditional economic analysis techniques used in the assessment of Public Private Partnership (PPP) projects are based upon the assumption that future cash flows are fully deterministic in nature and are not designed to account for risks involved in the assessment of future returns. In reality, many of these infrastructure projects are associated with significant risks stemming from the lack of knowledge about future cost and benefit streams. The fundamental premise of the PPP concept is to efficiently allocate risks between the public and the private partner. The return based on deterministic analysis may not depict a true picture of future economic outcomes of a PPP project for the multiple agencies involved. This deficiency underscores the importance of risk-based economic analysis for such projects. In this paper, the authors present the concept of Value-at-Risk (VaR) as a measure of effectiveness (MOE) to assess the risk share for the public and private entity in a PPP project. Bootstrap simulation is used to generate the risk profile savings in vehicle operating cost, and in travel time resulting from demand-responsive traffic. The VaR for Internal Rate of Return (IRR) is determined for public and private entity. The methodology is applied to a case study involving such a joint venture in India, the Mumbai Pune 

Expressway/National Highway 4 (MPEW/NH4), and fiscal implications from the perspective of the public and the private entities are examined. A comparison between deterministic and risk based economic analysis for MPEW/NH4 is presented. Risk analysis provides insightful results on the economic and financial implications from each participant’s viewpoint. 

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Arnab Chakraborty and Sabyasachee Mishra (2013)

Land Use and Transit Ridership Connections: Implications for State-level Planning Agencies

Land use and neighborhood characteristics have long been linked to transit ridership. Large-scale agencies, such as state departments of transportations, often make decisions that affect land use pattern and transit services. However, the interdependencies between them are seldom harnessed in decision-making. In this article, we develop and apply a transit ridership model based on land use and other neighborhood characteristics for an entire state. We then discuss its implications for regional and state-level decision-making. We chose the state of Maryland as our study area. Using a number of criteria, we subdivided the state into 1151 statewide modeling zones (SMZs) and, for each zone in the base year (2000), developed a set of variables, including developed land under different uses, population and employment densities, free-flow and congested speeds, current transport capacities, and accessibility to different transport modes. We estimated two sets of OLS-regression models for the base year data: one on the statewide SMZs dataset and other on subsets of urban, suburban and rural typologies. We find that characteristics of land use, transit accessibility, income, and density are strongly significant and robust for the statewide and urban areas datasets. We also find that determinants and their coefficients vary across urban, suburban and rural areas suggesting the need for finely tuned policy. Next we used a suite of econometric and land use models to generate two scenarios for the horizon year (2030) – business as usual and high-energy price – and estimated ridership changes between them. We use the resulting scenarios to show how demand could vary by parts of the state and demonstrate the framework’s value in large-scale decision-making.

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Allison Yoh, Norman Wong, Michael J. Smart, and Hiroyuki Iseki (2012)

Tool for Assessing Station Characteristics (TASC): Identifying Service Quality Improvements at Transit Stops and Stations

This particular poster presentation describes a web-based analysis tool that is hosted by the UCLA Institute of Transportation Studies and is publicly available to transit agencies interested in identifying which service quality changes (e.g. amenities, information, lighting, etc.) to transit stops/stations are most important for improving levels of transit users’ satisfaction.
 
This program is based on a series of research projects funded by California Department of Transportation since 2005 (see www.its.ucla.edu/research/EPIC/) in collaboration with researchers from multiple universities, including Hiroyuki Iseki from the National Center for Smart Growth.  This phase of research—TASC project—is groundbreaking in that it provides planners an analysis of the relative importance of various improvements, uses community-based input, and can be applied at the level of individual stops/stations, across a group of stops/stations, or across the transit system as a whole.  The program provides a graphical representation of users’ levels of satisfaction juxtaposed on top of the importance of various service qualities.  In short, it provides a clear indication of how best to invest increasingly scarce transit resources to improve customer satisfaction in attributes that matter to transit customers.
 
The poster focuses on a description of the process for using the tool – downloading the survey forms, conducting a user survey, uploading survey results, and downloading analysis results – and highlights examples of how the analysis can be performed at different levels of analysis to meet different needs.

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Hiroyuki Iseki and Rebecca Houtman (2012)

Evaluation of progress in contractual terms: Two case studies of recent DBFO PPP projects in North America

With continuous demand for transportation infrastructure and chronic funding shortfalls, public-private partnerships (PPPs) for infrastructure provision have garnered attention in recent years in the U.S. and abroad. High profile concession deals in Chicago and Indiana have raised concerns about the protection of public interests in PPPs. Such concerns have ignited heated debates, partly driven by ideology and vested interests, but also by questionable decisions made previously. While public agencies at all levels are interested in identifying successful PPP arrangements, the variety and complexity of PPP deals, combined with local factors unique to each project, make the development of a universal evaluation framework practically infeasible.

In order to improve our knowledge of the best PPP approaches for transportation infrastructure, we examine two recently completed Design-Build-Finance-Operate (DBFO) PPP deals in North America on six critical factors identified in the literature review: 1) pre-construction and construction risks; 2) asset valuation, traffic demand, and revenue risks; 3) non-compete provisions; 4) facility performance standards; 5) early termination terms; and 6) public and political acceptance. The case studies exhibit evidence of improved balances of risks, responsibility, costs, and benefits between the public and private sectors, incorporating knowledge from past experiences, and suggest an increasing sophistication of governmental decision-making and a move toward what we call a “middle-ground approach” to successfully addressing key issues of PPP implementation. As technical experience and familiarity with PPPs grow among transportation officials in the public sector, it is likely that success with and acceptance of PPPs will increase in coming years.

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Hiroyuki Iseki and Alexander Demisch (2012)

Examining the linkages between electronic roadway tolling technologies and road pricing policy objectives

The surge of road pricing projects in the U.S. and around the globe over the past 15 years has been enabled by a variety of new communication and transportation technologies. While all of these technologies increase the efficiency of roadway tolling vis-à-vis manual collection, no “best” configuration has emerged. Rather, optimal configurations depend on the objectives of the tolling effort, such as facility type, geographic scope, desire to price externalities, integration with other operations, and so on. While such policy objectives for road pricing have been examined extensively, little has been written on the explicit links between tolling technology configurations and policy objectives. This paper addresses this gap in the literature through an examination of eight road pricing programs. For each program we evaluate the conduct of the three technical tasks via the nine technology sets in light of six principal policy objectives of road pricing.

We find that two policy factors most often determine the type of roadway tolling technologies adopted: (1) the geographical scale of the road network tolled, and (2) the complexity of calculating the fee to be charged. The combination of these two factors can vary greatly – from flat fare tolling on individual facilities, to nationwide road networks priced with dynamic tolls that vary by vehicle class, time of day, and congestion level. We conclude that the challenge to the expanded implementation of road pricing is less about either pricing technologies or the objectives of pricing, but the politically and economically effective linking of the two.

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Hiroyuki Iseki, Michael Smart, Brian D. Taylor, and Allison Yoh (2012)

Thinking Outside the Bus

This is a short, accessible article that provides a synopsis of findings from the research titled “Tool Development to Evaluate the Performance of Intermodal Connectivity (EPIC)” in collaboration with UCLA Institute of Transportation Studies. This research has examined various factors that can substantially influence transit users’ perception of service quality at bus stops and trains stations, and also what factors transit managers think important to improve customers' satisfaction. Recently, the project has developed a tool for transit agencies to identify service quality improvements at transit facilities, which has been presented in the American Planning Association (APA) National Planning Conference in Los Angeles, April, 2012. Publications related to this research are listed under " FURTHER READING" on page 15.

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Chengri Ding and Shunfeng Song

Traffic Paradoxes and Economic Solutions: Policy Implications to China

Previous studies on traffic congestion have emphasized supply-side instruments, such as the expansion of road capacity and improving the management of traffic. However, researchers on transportation have identified several paradoxes in which the usual remedy for congestion—expanding the road system—is ineffective or even counterproductive. This paper presents three paradoxes of traffic flow in their general form and provides economic solutions to overcome them, with an emphasis on demand-side policies by examining the behavior of commuters and using pricing mechanisms.

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Jason Sartori, Terry Moore, and Gerrit Knaap (2011)

Indicators of Smart Growth in Maryland

Maryland is often referred to as the birthplace of smart growth, a movement in land use planning that contributed to what is now referred to as sustainability planning, sustainable development, and sustainable communities. Maryland adopted a Smart Growth Program in 1997 with the primary purposes being to use incentives to (1) direct growth into areas already developed and having public facilities, and (2) reduce the conversion of farm, forest, and resource land to urban uses.

The National Center for Smart Growth Research and Education at the University of Maryland was established in 2000 in large part because of Maryland’s leadership in the field of smart growth. Its mission is to provide research and leadership training on smart growth and related land use issues in Maryland and in metropolitan regions around the nation. Thus, a key focus of the Center’s research is Maryland’s Smart Growth Program: where is it effective, and how can it be improved?

This report provides some indicators (also called performance measures) that suggest answers to those questions. The term “suggest” is important: (1) there are many limitations of any assessment based on indicators, no matter how well developed, and (2) the indicator assessment reported here is only in its preliminary stages. Understanding the limitations of indicators is critical to interpreting their significance. Thus, Section 2 and Appendix B of this report discuss in some detail data, methods, and limitations.

Researchers and policymakers acknowledge those limitations, but that acknowledgement does not slack their desire for indicators that say something concrete about whether desired outcomes are being achieved, and at what cost in direct expenditures and spillover effects; and about directions for policy that would increase the desired outcomes, reduce the costs, or both. Sections 3 and 4 address those issues.

Section 3 reports indicators for six categories of issues. Population and employment growth drive development. That development is the immediate concern of the two thrusts of the Maryland Smart Growth Program: it puts pressure on the natural areas that the Program wants to protect, and it can occur in development patterns that not only eliminate and vitiate those natural areas, but also are inefficient from the perspective of providing transportation and other infrastructure and, ultimately housing (and other buildings). Some of the key findings:

  • Population. The population growth rate in Maryland approximately equals the national average. The indicators give no direct, rigorous, or even casual evidence that the Smart Growth Program either increased or decreased the amount or composition of population growth statewide.
  • Employment. Employment and other measures of economic activity have consistently grown over the last two decades in Maryland and all its regions. From 2000 to 2009, Maryland had the 13th highest annualized rate of job growth (1.0%) among the 50 states. Indicator data allow the conclusion that the Smart Growth Program did not stop economic growth, but they do not allow a conclusion about whether the Program increased or decreased that growth from what it would have been in the absence of the Program.
  • Transportation. For most measures of transportation performance that are standardized, Maryland looks like other states: VMT, congestion, and car ownership have risen consistently over time. Maryland has higher transit ridership than most states, some of which may be attributable to the Smart Growth Program but most of which is attributable to Maryland’s proximity to Washington, D.C. and its own historical investments in transit (especially in Baltimore and in suburban Maryland) that pre-date the Program.
  • Development patterns. Urban development continued in Maryland at densities lower than several comparison states from 1990 to 2000. Most of that growth has not been infill of urban areas: the predominant form of urban development in Maryland remains suburban. Three-fourths of the new single-family acres were developed outside PFAs since 1997. Indicators of Smart Growth in Maryland NCSGRE January 2011 Page 3 While this indicator has shown some improvement in recent years, the share of parcels developed outside PFAs continues to demonstrate an increase over time. Despite increases in density for the state as a whole (which is inevitable if there is any population growth), a substantial amount of Maryland’s new growth has been occurring in the exurban areas of the state. The share of population that lives within a half-mile of rail transit stations, however, has generally risen over time.
  • Housing. Although the single-family share of new housing construction has fallen recently, the single-family share of housing in Maryland is high for a highly urbanized state. Housing prices have inflated faster in Maryland than most other states the last few decades, clearly raising questions of affordability, which varies across the state.
  • Natural areas. The trends for acres of farm and forest land have been steadily downward in Maryland and the U.S. for a long time, but data suggest that rate of decline is decreasing. Maryland and its counties have protected well over 1.3 million acres of land. There is still, however, a substantial amount and percent of critical land that is not protected. Measures of air quality are mainly stable or improving, yet measures of water quality demonstrate poor conditions in watersheds across the state.

If the indicators here are leaning in any direction, it is that Maryland has not made substantial progress toward improving its performance in many of the areas pertaining to smart growth. There are, however, reasons to qualify a direct conclusion like that one:

  • Without the kind of research design that goes well beyond the reporting of indicators into statistical controls for multiple explanatory variables, there is no solid way to rebut the hypothesis that what the Maryland Smart Growth Program did was to prevent many indicators from getting much worse than they are.
  • Things take time. Many changes in technology, social attitudes, prices, and the built environment occur slowly. Indicators of Smart Growth in Maryland NCSGRE January 2011 Page 4
  • If it is too early to expect to see much by way of results (e.g., changes to trends) then perhaps indicators of outcomes should be supplemented by indicators of inputs: of efforts made to stimulate future change (i.e., the number and strength of policies to change the patterns and effects of growth).

Related Resource

Indicators of Smart Growth in Maryland: Appendices

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Sabyasachee Mishra and Timothy F. Welch (2011)

A Joint Travel Demand and Environmental Model to Incorporate Emission Pricing for Large Transportation Networks

Emission reduction strategies are gaining greater attention to support the national objective for a sustainable and green transportation system. A large percent of emission contribution arises from transportation modes are primarily from auto and truck travel. Reductions in highway travel require prudent planning strategies and modeling user’s response to planner’s policies. Modeling planning goals and user’s response is a challenging task. In this paper the authors present a joint travel demand and environmental model to incorporate vehicle emission pricing (VEP) as a strategy for emission reduction. First, the travel demand model determines the destination, mode and route choice of the user’s in response to the VEP strategy set by the planner. Second, the emission model provides NOx, VOC, and CO2 estimates at a very detailed level. A Base-case and three models are proposed to incorporate VEP in a multimodal transportation network. The objective function of the Base-case is the minimization of Total System Travel Time (TST), and the models are designed with the objective of minimizing of Total System Emission (TSE). User Equilibrium method is used for travel to model user responses and solved by Frank Wolfe algorithm. The Base-case represents “do-nothing” conditions and the three models address the interactions between planner’s perspectives and user responses to VEP strategies. The proposed model is applied to Montgomery County’s (located in the Washington DC-Baltimore region) multimodal transportation network. The case study results show that VEP can be used as a tool for emission reduction in transportation planning and policy.

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Arnab Chakraborty and Sabyasachee Mishra (2011)

A Case for Increased State Role in Transit Planning: Analyzing Land Use and Transit Ridership Connections Using Scenarios

Land use and neighborhood characteristics have long been linked to transit ridership. Large-scale agencies, such as state departments of transportations, often make decisions that affect land use pattern and transit services. However, the interdependencies between them are seldom harnessed in decision-making. In this article, we develop and apply a transit ridership model based on land use and other neighborhood characteristics for an entire state. We then discuss its implications for regional and state-level decision-making. We chose the state of Maryland as our study area. Using a number of criteria, we subdivided the state into 1151 statewide modeling zones (SMZs) and, for each zone in the base year (2000), developed a set of variables, including developed land under different uses, population and employment densities, free-flow and congested speeds, current transport capacities, and accessibility to different transport modes. We estimated two sets of OLS-regression models for the base year data: one on the statewide SMZs dataset and other on subsets of urban, suburban and rural typologies. We find that characteristics of land use, transit accessibility, income, and density are strongly significant and robust for the statewide and urban areas datasets. We also find that determinants and their coefficients vary across urban, suburban and rural areas suggesting the need for finely tuned policy. Next we used a suite of econometric and land use models to generate two scenarios for the horizon year (2030) – business as usual and high-energy price – and estimated ridership changes between them. We use the resulting scenarios to show how demand could vary by parts of the state and demonstrate the framework’s value in large-scale decision-making.

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Yohannes Weldegiorgis, Sabyasachee Mishra, and Manoj K. Jha (2011)

Comparing Driver and Capacity Characteristics at Intersections With and Without Red Light Cameras

The primary purpose of installing Red Light Cameras (RLCs) is to improve intersection safety by discouraging motorists to cross the intersection when the signal for approaching vehicles turns red. Due to the fear of being fined when crossing an RLC equipped intersection at the onset of the red signal, many approaching vehicles may have a tendency of stopping during the yellow phase. This tendency may impact intersection capacity, which can be significant in congested transportation networks during rush hours, especially when several intersections are equipped with RLCs along a sequence of traffic signals, resulting in a disruption of traffic progression. In order to examine the driver and capacity characteristics at intersections with RLCs and compare them with those without RLCs we develop a binary probit choice model to understand driver's stop and go behavior at the onset of yellow intervals, also known as dilemma zone. Further, in order to capture the impact to intersection capacity at intersections with RLCs we develop a probabilistic computational procedure using data from ten intersection pairs (with and without RLCs) in the Baltimore area. The results indicate that, in general, RLCs reduce the intersection capacity since driver's travel behavior is influenced by the presence of the cameras. Other contributory factors for the so-called capacity reduction, such as driver population (e.g., familiar vs. unfamiliar drivers) and traffic-mix (e.g., trucks vs. passenger cars) characteristics have been left for future works.

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Hiroyuki Iseki

Examination of Regional Transit Service Under Contracting: A Case Study in the Greater New Orleans Region

Many local governments and transit agencies in the United States face financial difficulties in providing adequate public transit service in individual systems, and in providing sufficient regional coordination to accommodate transit trips involving at least one transfer between systems. These difficulties can be attributed to the recent economic downturn, continuing withdrawal of the state and federal funds that help support local transit service, a decline in local funding for transit service in inner cities due to ongoing suburbanization, and a distribution of resources that responds to geographic equity without addressing service needs.

This study examines two main research questions: (1) the effect of a “delegated management” contract on efficiency and effectiveness within a single transit system, and (2) the effects of a single private firm—contracted separately by more than one agency in the same region—on regional coordination, exploring the case in Greater New Orleans. The current situation in New Orleans exhibits two unique transit service conditions. First, New Orleans Regional Transit Authority (RTA) executed a “delegated management” contract with a multinational private firm, outsourcing more functions (e.g., management, planning, funding) to the contractor than has been typical in the U.S. Second, as the same contractor has also been contracted by another transit agency in an adjacent jurisdiction—Jefferson Transit (JeT), this firm may potentially have economic incentives to improve regional coordination, in order to increase the productivity and effectiveness of its own transit service provision.

Although the limited amount of available operation and financial data has prevented us from drawing more definitive conclusions, the findings of this multifaceted study should provide valuable information on a transit service contracting approach new to the U.S.: delegated management. This study also identified a coherent set of indices with which to evaluate the regional coordination of transit service, the present status of coordination among U.S. transit agencies, and barriers that need to be resolved for regional transit coordination to be successful.

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Sabyasachee Mishra, Xin Ye, Fred Ducca, and Gerrit Knaap (2011)

A Functional Integrated Land Use-Transportation Model for Analyzing Transportation Impacts in the Maryland-Washington D.C. Region

The Maryland-Washington, DC region has been experiencing significant land-use changes and changes in local and regional travel patterns due to increasing growth and sprawl. The region’s highway and transit networks regularly experience severe congestion levels. Before proceeding with plans to build new transportation infrastructure to address this expanding demand for travel, a critical question is how future land use will affect the regional transportation system. This article investigates how an integrated land-use and transportation model can address this question. A base year and two horizon-year land use-transport scenarios are analyzed. The horizon-year scenarios are: (1) business as usual (BAU) and (2) high gasoline prices (HGP). The scenarios developed through the land-use model are derived from a three-stage top-down approach: (a) at the state level, (b) at the county level, and (c) at the statewide modeling zone (SMZ) level that reflects economic impacts on the region. The transportation model, the Maryland Statewide Transport Model (MSTM), is an integrated land use-transportation model, capable of reflecting development and travel patterns in the region. The model includes all of Maryland, Washington, DC, and Delaware, and portions of southern Pennsylvania, northern Virginia, New Jersey, and West Virginia. The neighboring states are included to reflect the entering, exiting, and through trips in the region. The MSTM is a four-step travel-demand model with input provided by the alternative land-use scenarios, designed to produce link-level assignment results for four daily time periods, nineteen trip purposes, and eleven modes of travel. This article presents preliminary results of the land use-transportation model. The long-distance passenger and commodity-travel models are at the development stage and are not included in the results. The analyses of the land use-transport scenarios reveal insights to the region’s travel patterns in terms of the congestion level and the shift of travel as per land-use changes. The model is a useful tool for analyzing future land-use and transportation impacts in the region. 

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Allison Yoh, Hiroyuki Iseki, Mike Smart, and Brian D. Taylor

Hate to Wait: Effects of Wait Time on Public Transit Travelers’ Perceptions

A large and growing body of research suggests that transit users hate to wait. Given broad policy goals to increase public transit use in U.S. cities, this research sheds light on cost-effective ways to increase transit use by decreasing the perceived burdens of waiting at stops and stations. The goal of this study was to determine (a) the relative importance of stop and station amenities and attributes and (b) how the importance of these amenities and attributes varies with wait time. For this goal to be accomplished and for the duration of wait time when amenities become important to be determined a transit user survey that asked more than 2,000 travelers to rate both the importance of amenities at their stops or stations and their wait times was analyzed. Regardless of wait time, safety and on-time performance were paramount to riders; these also ranked highest relative to all other station and stop amenities examined. Lighting, cleanliness, information, shelter, and the presence of guards were less important to travelers when waits were short, but were more important with longer wait times. Thus, improving service frequency and reliability reduces the need for amenities at stations. This end suggests that when transit managers have a choice and when riders feel safe and secure managers should favor service improvements over station and stop amenities. Finally, some amenities become more important with long wait times, such as restrooms and food and drink facilities. Although provision of basic needs amenities is intuitive, restrooms and food and drink sales are most likely present at high-passenger-volume, high-service-frequency stops and stations, where they are valued least by travelers.

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Maureen L. Cropper, Yi Jiang, Anna Alberini, and Patrick Baur (2010)

Getting Cars Off the Road: The Cost-Effectiveness of an Episodic Pollution Control Program

Ground level ozone remains a serious problem in the United States. Because ozone non-attainment is a summer problem, episodic rather than continuous controls of ozone precursors are possible. We evaluate the costs and effectiveness of an episodic scheme that requires people to buy permits in order to drive on high ozone days. We estimate the demand function for permits based on a survey of 1,300 households in the Washington, DC metropolitan area. Assuming that all vehicle owners comply with the scheme, the permit program would reduce VOCs by 50 tons and NOx by 42 tons per Code Red day at a permit price of $75. Allowing for non-compliance by 15% of respondents reduces the effectiveness of the scheme to 39 tons of VOCs and 33 tons of NOx per day. The cost per ozone season of achieving these reductions is approximately $9 million (2008 USD). This compares favorably with permanent methods of reducing VOCs that cost $645 per ton per year.

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Sabyasachee Mishra, Tom V. Mathew, and Snehamay Khasnabis (2010)

Single Stage Integer Programming Model for Long Term Transit Fleet Resource Allocation

The authors present a procedure for resource allocation among transit agencies for transit fleet management, specifically focusing on the purchase of new buses and rebuilding of existing buses. The model is formulated as a non-linear optimization problem of maximizing the total weighted average remaining life of the fleet subject to budgetary, policy and other constraints. The problem is solved using Integer Programming (IP) and its application is demonstrated through a case study utilizing actual transit fleet data from the Michigan Department of Transportation.

This proposed model is an extension of earlier research on a Two-stage sequential optimization method, solved by Linear Programming (LP). The proposed model has a Single-stage structure designed to attain a better solution by allocating resources among different improvement options and different agencies in a single step. A comparison of the results by the two methods shows that while both approaches are viable, the Single- stage approach produces better results. The proposed model, as demonstrated in the case study is considered more robust, compact, efficient and suitable for both short term and long range planning. 

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Tom V. Mathewa, Snehamay Khasnabisb, and Sabyasachee Mishra (2010)

Optimal Resource Allocation Among Transit Agencies for Fleet Management

Most transit agencies require government support for the replacement of their aging fleet. A procedure for equitable resource allocation among competing transit agencies for the purpose of transit fleet management is presented in this study. The proposed procedure is a 3-dimensional model that includes the choice of a fleet improvement program, agencies that may receive them, and the timing of investments. Earlier efforts to solve this problem involved the application of one or 2-dimensional models for each year of the planning period. These may have resulted in suboptimal solution as the models are blind to the impact of the fleet management program of the subsequent years. Therefore, a new model to address a long-term planning horizon is proposed. The model is formulated as a non-linear optimization problem of maximizing the total weighted average remaining life of the fleet subjected to improvement program and budgetary constraints. Two variants of the problem, one with an annual budget constraint and the other with a single budget constraint for the entire planning period, are formulated. Two independent approaches, namely, branch and bound algorithm and genetic algorithm are used to obtain the solution. An example problem is solved and results are discussed in details. Finally, the model is applied to a large scale real-world problem and a detailed analysis of the results is presented. 

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Snehamay Khasnabis, Sunder Lall Dhingra, Sabyasachee Mishra, and Chirag Safi (2010)

Mechanisms for Transportation Infrastructure Investment in Developing Countries

In this paper, the authors examine different investment mechanisms for transportation infrastructure projects involving the private enterprise in developing countries. Roles identified vary from those of a financier to an operator for successful public-private ventures. A case study involving such a joint venture in India, the Mumbai Pune Expressway/National Highway 4 (MPEW/NH4) is presented, and fiscal implications of the program, both from the perspective of the public and the private enterprise are examined. The study concludes that if properly planned, joint ventures can be mutually beneficial. A joint public-private program may enable the public sector to use the resources saved for other public projects. It also provides the private agency an opportunity to invest monies in a profitable enterprise that yields social benefits, (e.g. improving mobility, promoting economic development, etc.). Careful analysis must be conducted before the project is undertaken to assess the financial and economic implications of the project from each participant’s viewpoint, with due regard to risks and uncertainties associated with such long term investments. 

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Nikhil Kaza, Gerrit Knaap, and Douglas Meade (2008)

Exploring Alternative Futures Using a Spatially Explicit Econometric Model

This paper illustrates the application of various forecasting methodologies in constructing multiple scenarios for the state of Maryland using Long term Inter Industry Forecasting Tool that tracks inter-industry outputs at a macro scale, and State Employment Model that disaggregates these outputs to the states. We then use accessibility, land availability and observed relationships of employment categories to distribute employment at a county level. In this paper, we identify the possible advantages and pitfalls of using large scale economic models to drive employment forecasts at the county level. This framework allows for simulating the implications of macroeconomic scenarios such as changes in exchange rates and unemployment levels, as well as local land use and transportation policies on local employment and demographics. In particular, we focus on two scenarios as test cases both of which involve very different ideas about how future might unfold and their effects on land use and transportation policy prescriptions. One of the scenarios involves, among others, rises in health care spending over the next few years and the other involves increases in energy prices. As will be shown, they have different spatial effects and suggest different policy actions on the part of various governments.

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Gerrit Knaap and John Frece (2007)

Smart Growth in Maryland: Looking Forward and Looking Back

Spring of 2007 will mark the 10th anniversary of the passage of Maryland’s Smart Growth and Neighborhood Conservation Initiative; an effort designed to discourage sprawl development, foster more compact communities, protect the best remaining farms and open space in the state, and save taxpayers from the growing cost of providing services and infrastructure to serve far-flung development. Almost before its various provisions took effect in 1997 and 1998, the Maryland initiative generated interest and acclaim across the country. It received numerous awards and became the principal legacy of the program’s primary architect, former Governor Parris N. Glen- dening. Governors in other states, such as New Jersey, Colorado and Massachusetts, instituted their own “smart growth” proposals, often modeled after portions of the Maryland program. Even the popularity and wide usage of the now omnipresent phrase “smart growth” can be attributed in large part to the Maryland program.

But, what has been the effect of Maryland’s Smart Growth pro- gram? Looking at it some ten years later, has it worked? Did it accomplish what it was designed to do? What have been the strengths and weaknesses of the Maryland approach, and how can lessons from the Maryland experience be used to offer a new set of policymakers in Maryland, as well as elsewhere in the nation, practical suggestions on how to make smart growth smarter?

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Reid Ewing (2006)

Why We Should Care About Traffic

Moving traffic efficiently is something transportation planners should know and care about, because our "customers" (the traveling public) find traffic so frustrating and because competent traffic engineers aren't always around.

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Feng Zhang, Kelly J. Clifton, Qing Shen (2005)

Reexamining ICT Impact on Travel Using the 2001 NHTS Data for Baltimore Metropolitan Area

This paper presents an empirical examination of the relationship between information and communications technology (ICT) and travel. The primary research objective is to examine the effects of several indicators of ICT usage on three measures of travel outcomes. The ICT indicators include the frequency of Internet use, the number of mobile phones, and the presence of a telephone at home for business purposes. The travel outcomes examined are vehicle miles traveled (VMT), total daily trips, and daily walking trips. Using the 2001 national household travel survey (NHTS) data for Baltimore metropolitan area, a linear regression model is estimated for VMT and two Poisson regression models are estimated for, respectively, total daily trips and daily walking trips. The empirical results suggest simultaneous existence of substitution and complementarity interactions between ICT and travel, with complementarity as the dominant form. Implications of the research findings are discussed.

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Reid Ewing (2005)

Can the Physical Environment Determine Physical Activity Levels?

Can the physical environment determine physical activity levels? Does your place of residence affect your level of physical activity and ultimately your weight and health? There is relatively strong evidence of association between compact development patterns and use of active travel modes such as walking and transit. There is weaker evidence of linkage between compact development, overall physical activity, and downstream weight and health effects.

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Reid Ewing, Steven J. Brown, and Aaron Hoyt (2005)

Traffic Calming Practice Revisited

Since the Publication of ITE's "Traffic Calming: State of the Practice," the field of traffic calming has matured. This feature summarizes a 2004 survey of traffic calming practices in 21 leading jurisdictions. The results are compared to surveys conducted for the national report in the 1990s.

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Reid Ewing, Christopher V. Forinash, and William Schroeer (2005)

Neighborhood Schools and Sidewalk Connections: What Are the Impacts on Travel Mode Choice and Vehicle Emissions

The study reported here was the first to examine the relationship between school location, the built environment around schools, student travel to school, and the emissions impacts of this travel. Students with shorter walk and bike times to school proved significantly more likely to walk or bike—which argues for neighborhood schools. Students who have access to sidewalks along main roads were also more likely to walk—which argues for improvements in sidewalk networks.

Neighborhood schools that can be reached by walking and biking can increase the amount of walking and biking to school, can shorten trip distances,and can reduce motor vehicle emissions significantly.

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Reid Ewing, Michael R. King, Stephen Raudenbush, and Otto Jose Clemente (2005)

Turning Highways into Main Streets: Two Innovations in Planning Methodology

Visual preference surveys have become a popular tool among planning practitioners. By tapping visual media, such surveys help to illustrate physical design alternatives in ways that words, maps, and other media cannot. They have found applications in visioning projects, design charrettes, and other physical planning activities with heavy public involvement. With little additional effort, a visual preference survey can be restructured as a visual assessment study, which provides more useful information. Confounding variables can be controlled, and underlying qualities that cause certain scenes to be preferred can be identified. This article reports on a visual assessment study of state highways, identifying the physical features that can make them into main streets.

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Reid Ewing and Richard J. Kuzmyak (2005)

Comparing Forecasting Methods: Expert Land Use Panel vs. Simple Land use Allocation Model

An Expert Land Use Panel was used to forecast the land use impacts of a major highway project in the Washington, DC area, the Inter-County Connector. What makes this panel noteworthy is the fact that a subgroup of panelists, convinced that the accessibility impacts of the highway were not being adequately considered by the majority, developed a simple land use allocation model which they then used to produce independent forecasts. This allows us to compare more intuitive and ad hoc forecasts based only on expert opinion with those based on a formal land use allocation model. At least in this case, the two differed sufficiently to suggest that the two processes are not mere substitutes for one another. This prompts us to recommend that subsequent panels be fed accessibility data early in the process to inform their intuitive judgments, and that simple land use allocation models be considered as a complement to expert opinion.

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Gerrit Knaap and Yan Song (2005)

The Transportation-Land Use Policy Connection

In this paper, we explore the transportation-land use policy connection. More specifically, we consider the question: can land use policy be used to alter transportation behavior? The answer is of some importance. If the answer is yes, then there is hope that land use policies can be designed and implemented that will bring some relief to the gridlock and complex transportation problems facing US metropolitan areas. This is the underlying assumption behind most smart growth policy reforms. If the answer is no, then land use policy may still be important, but is not likely to play an important role in resolving transportation issues.

We proceed as follows. First we offer a schematic that identifies necessary conditions for land use policy to play a role in addressing transportation issues. Specially,we argue that for land use policy to play an effective role, three conditions must hold.  First, land use must be able to alter transportation behavior. Second, transportation infrastructure must not fully determine land use. Third, the condition on which we consider most extensively, land use policy must significantly and constructively affect land use. After presenting the schematic, we consider the evidence on each of these conditions. Based on our review of the evidence, we conclude that land use policy can play an effective role in addressing transportation issues, but that the role is likely to be small, often counter productive, and most effective at the neighborhood scale.

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James Cohen (2004)

Water Supply as a Factor in Local Growth Management Planning in the U.S.: A Review of Current Practice, and Implications for Maryland

In February of 2002, as aquifers, streams and reservoirs in many parts of Maryland reached record lows, 72 members of the state's General Assembly signed a letter to the then-Governor Parris Glendening requesting the creation of a special commission to investigate ways of stemming the decline of water supplies. A year later, Governor Robert Ehrlich signed an executive order creating a Water Resource Management Advisory Committee. Among other activities, that committee is directed to review ongoing scientific research on climate change and its regional impacts on water sources; assess the adequacy of current governmental laws, policies, regulations, resources, regulatory enforcement and monitoring programs directed to water resource management, development, conservation and protection in the State; and make recommendations for the actions needed (and the associated costs and funding alternatives) to ensure that the State’s water resources are used “in a manner consistent with their long-term sustainable use and protection.”

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Shengling Chang, Ping Sung, and Aimee LaMontagne (2004)

Can City Lifestyle be a Catalyst for Smart Suburban Change?: A Comparative Investigation into How Asian and Latino Immigrants’ Prior Urban Experiences

The research investigates how Asian and Latino immigrants’ prior urban experiences can inform the future planning and growth of suburban communities in Maryland. The investigation of Maryland immigrants’ various built environment (dwelling, landscape, neighborhood, transportation mode) preferences will result in a set of ecologically appropriate and culturally sensitive design guidelines that will help shape the future of the rapidly growing suburban communities.

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Kelly J. Clifton, Gary Davies, William G. Allen, and Noah Radford (2004)

Pedestrian Flow Modeling for Prototypical Maryland Cities

Pedestrian safety is emerging as a major area of concern for MPO's and planning agencies. Typically, pedestrian safety has been analyzed by either examining the absolute number of pedestrian crashes at a location, or computing an exposure rate from the number of crashes and the traffic volume. A more desirable measure would be an exposure rate based on the pedestrian volume, but it has not proven feasible to obtain pedestrian flow volumes on a widearea basis to support this analysis. This report describes a pedestrian flow modeling process that was developed under the sponsorship of the Maryland DOT and the University of Maryland National Center for Smart Growth. The process provides micro-scale daily pedestrian flows on all sidewalks and crosswalks in a substantial coverage area. Two test cases were analyzed: an urban scenario comprising about 10 square miles of downtown Baltimore, and a suburban scenario comprising about 15 square miles of Langley Park in Prince Georges and Montgomery Counties.

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Richard Etlin (2004)

The Future of Tysons Corner: A Fifteen-Point Blueprint for the New “Downtown” of Northern Virginia

Joel Garreau's book "Edge City" made Tysons Corner synonymous with auto-centric sprawl, yet the Tysons Corner Comprehensive Plan aims to transform the area into a pedestrian- and transit-friendly downtown for Fairfax, Virginia. This report by Distinguished University of Maryland Professor, Richard Etlin, proposes 15 recommendations to improve upon the comprehensive plan and realize a new vision for development in Tysons Corner.

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Reid Ewing (2003)

Building Environment to Promote Health

Editorial published in the "Journal of Epidemiology & Community Health" on the future of collaboration between public health and urban planning professionals.

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Jayanthi Rajamani, Chandra R. Bhat, Susan Handy, Gerritt Knaap, and Yan Song (2003)

Assessing the impact of urban form measures in nonwork trip mode choice after controlling for demographic and level-of-service effects

The relationship between travel behavior and the local built environment continues to be a contentious issue, despite several research efforts in the area. The current paper investigates the significance and explanatory power of a variety of urban form measures on nonwork activity travel mode choice. The travel data used for analysis is the 1995 Portland Metropolitan Activity Survey conducted by Portland Metro. The database on the local built environment was developed by Song (2002) and includes a more extensive set of variables than previous studies that have examined the relationship between travel behavior and the local built environment using the Portland data. A multinomial logit mode choice model results indicate that higher residential densities and mixed-uses promote walking behavior for nonwork activities.

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Reid Ewing (2003)

Travel and Environmental Implications of School Siting

Travel and Environmental Implications of School Siting, released by the EPA on October 8, 2003, is the first study to empirically examine the relationship between school locations, the built environment around schools, how kids get to school, and the impact on air emissions of those travel choices. Over the next few decades, communities making decisions about the construction and renovation of thousands of schools will be challenged to meet multiple goals -- educational, fiscal, and environmental. The study finds that:

School proximity to students matters. Students with shorter walk and bike times to school are more likely to walk or bike.

The built environment influences travel choices. Students traveling through pedestrian-friendly environments are more likely to walk or bike.

Because of travel behavior differences, school location has an impact on air emissions. Centrally located schools that can be reached by walking and bicycling result in reduced air emissions from driving.

More data collection and research are needed to add further to the understanding of these effects. Specifically, improved data about both school travel and the built environment as well as new modeling techniques can build on these results.

For some time, there has been a trend toward construction of big schools and requirements for large sites. Guidelines, recommendations, and standards that encourage or require building large schools on new campuses or discourage renovation are embedded in a variety of state and local regulations, laws and funding formulas. This study provides important information about the effect of school location on how children get to school. It shows that school siting and design can affect choices of walking, biking, or driving. In turn, these changes in travel choices could affect traffic congestion, air pollution, and school transportation budgets.

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Gerrit Knaap (2002)

Talking Smart in the United States

As in many countries around the world, concerns about contemporary urban development patterns and their effects on the natural and social environment are high and rising in the United States. Though these concerns are not new, the recent period of sustained economic growth has led to both rapid urban expansion and falling relative concerns about other problems like crime, unemployment, and government deficits. Urban sprawl is now a major public policy issue (U.S. Office of Technology Assessment 1995, U.S. General Accounting Office (GAO) 1999, GAO 2000).

How to address -- even define -- the problem, however, remains unresolved and contentious. Some view urban sprawl as a major threat to environmental quality, fiscal stability, and human health. Those with this point of view support policy reforms sometimes called smart growth, new urbanism, and sustainable development (Ewing 1997, Smart Growth Network 2002). To others, sprawl is simply the result of increases in population, rising real incomes, and the expression of consumer demands (Brueckner 1999). To those with this point of view, there is little evidence that urban sprawl has adverse social or environmental consequences or warrants a policy response (Gordon and Richardson 1997, Urban Futures 2002). In a nation rich in land resources and steeped in traditions of private property rights, this view is not easily dismissed.

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Yan Song and Gerrit Knaap

Internally Connected, No Commercial, With a Touch of Open Space: The Neighborhoods of New Homes in the Portland Metropolitan Area

For many years, neighborhoods have been classified as either “suburban” or “traditional.” But new homes today are built in many different types of neighborhoods with many different design features. In this paper, we develop a quantitative method for classifying the neighborhoods of new homes in the Portland metropolitan area. We proceed in three steps.  First we measure urban form attributes of neighborhoods around newly developed homes.  We then use factor analysis to identify a small set of factors that capture essential differences in urban form. Finally we use cluster analysis on these factor scores to identify distinctly different neighborhood types. Applying these methods to neighborhoods around new single family homes in the metropolitan Portland, Oregon, we are able to identify eight factors of urban form and six neighborhood types. We then show that most new single family homes in metropolitan Portland are built in new suburban neighborhoods but a substantial portion is occurring in traditional urban neighborhoods. 

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