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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Research in Progress (RIP)</title>
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      <title>A Multidimensional Network-Based Approach to Modeling Urban Growth in Texas Triangle Megaregion </title>
      <link>https://rip.trb.org/View/2470763</link>
      <description><![CDATA[This paper proposes a network analysis framework based on geographic information systems (GIS) to study the development of megaregions in support of urban planning and policy-making. The framework includes a new approach to model geo-shaped polygon data of census places as the Place Geo-Adjacency Network (PGAN). In particular, the integration of descriptive network analysis and degree distribution analysis supports the study of spatial connections, geospatial growth, hub effects, and expansion patterns in megaregions. To demonstrate this framework, a case study was conducted on four US megaregions to study their growth and expansion in the last 40 years since 1980. The degree distribution analysis captures the small-world property and quantifies the level of geospatial connectivity influenced by the hub effects. Policymakers can use the model as a decision support for urban planning and policy design to reduce disparities and improve connectivity in megaregion areas.]]></description>
      <pubDate>Mon, 09 Dec 2024 19:02:41 GMT</pubDate>
      <guid>https://rip.trb.org/View/2470763</guid>
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      <title>Patterns and drivers of urban expansions in the Texas Triangle: Case study of the Austin metropolitan region</title>
      <link>https://rip.trb.org/View/2459117</link>
      <description><![CDATA[Urban expansions result from population and economic growth; yet they often come together with diseconomies, for example, congestion, pollution, and resource depletion. Understanding urban expansion patterns, dynamics, and trends is essential to formulate public interventions aimed at achieving long-term sustainability. This study makes the needed effort through a case study of the Texas Triangle megaregion. Texas Triangle is one of the fastest growing megaregions in the United States. In the past thirty years (1990-2020), the region’s population grew by 89%, from 12.32 million to 23.02 million. Accompanying the fast and large population growth was the urban expansion of matched speed and size. The style of Texas’s past expansion has made it known as one of America’s most sprawling and automobile-dependent regions. Texas Triangle’s population is projected to continue to grow rapidly, reaching 28.71/32.88 million by 2050 in the moderate/fast growth scenario. With the extensive growth in the past and in the forthcoming future, the megaregion is facing many daunting challenges to be addressed urgently. What adds to the urgency is the annual threats from natural disasters. For instance, Hurricanes landed in Houston and the Gulf Coast in recent years have caused billions of dollars of property damages, hundreds of deaths, and thousands of households being displaced. The impacts of the disasters have gone beyond the Houston region, reaching to the rest of the Triangle and other counties and neighboring states. The purpose of the study is to analyze Texas Triangle’s growth patterns and dynamics and simulate future scenarios of urban expansion. A specific interest of the study is in the role that major transportation investments and projects have played in the past in Texas Triangle’s expansion. Findings obtained from analyzing the past and future trends will help planners and policy makers to formulate public interventions to channel future growth towards a sustainable path. The project will utilize SLEUTH, an open source, cellular automaton modeling tool that has been widely applied to model land use/land cover changes. The main datasets for the project include 2001-2016 land use/land cover imageries available from the United States Geological Survey's (USGS’) National Land Cover Database (NLCD). Additional data on the socioeconomic characteristics and transportation networks for the study area will be processed from the U.S. censuses or obtained from Texas Department of Transportation (TxDOT).]]></description>
      <pubDate>Sat, 23 Nov 2024 10:16:49 GMT</pubDate>
      <guid>https://rip.trb.org/View/2459117</guid>
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    <item>
      <title>The Extensions and Applications of Megaregional Transportation Planning Model</title>
      <link>https://rip.trb.org/View/1889098</link>
      <description><![CDATA[This project will extend the Megaregional Transportation Planning
Model developed by incorporating functions of economic and
environmental impact analyses. The extended model will be
implemented to examine the impacts of policy, plans, and projects
in Texas Triangle.]]></description>
      <pubDate>Fri, 29 Oct 2021 15:41:25 GMT</pubDate>
      <guid>https://rip.trb.org/View/1889098</guid>
    </item>
    <item>
      <title>Advancing Social/Racial Equity and Congestion Relief: Understanding the Travel Needs of Under-served Populations that Rely on Transportation Network Companies in the San Francisco area</title>
      <link>https://rip.trb.org/View/1885422</link>
      <description><![CDATA[Transportation Network Companies (TNCs) enable travelers to order and pay for rides on-demand using an online application that connects them with drivers using their personal vehicles. While these modes present opportunities to increase individual mobility and access, they also can worsen congestion and increase vehicle emissions. Researchers explored factors impacting the willingness to use pooled TNCs and identified strategies/policies that could be employed to reduce congestion from TNC use. Researchers conducted a literature review, interviews with TNC experts, semi-structured interviews with lower-income, non-White TNC users, and small group discussions with lower- income, non-White TNC users. This research resulted in several key findings including the importance of travel time in the decision to pool, greater focus on meeting the needs of people with disabilities, key operational and safety drawbacks of public transportation (e.g., delayed vehicles, harassment onboard), and the importance of personal safety in transportation decision-making. These findings informed several policy options to better understand how TNC benefits can be maximized while minimizing their negative externalities, such as congestion and vehicle emissions.]]></description>
      <pubDate>Thu, 14 Oct 2021 12:23:38 GMT</pubDate>
      <guid>https://rip.trb.org/View/1885422</guid>
    </item>
    <item>
      <title>Compilation: A Statement of Vulnerability Regarding Texas' Megaregion Corridors</title>
      <link>https://rip.trb.org/View/1881790</link>
      <description><![CDATA[Previous CM2-based research developed a rubric and identified vulnerable communities on the Texas Triangle and Gulf Coast Megaregions. The CVI shows a combination of the need via the socioeconomic criteria and the purpose by highlighting the percentage of income spent on transportation. That these individuals and families must spend a larger portion of their income moving around leaves less for all other needs.  Disposable income might be used to access education or better employment, spending that could lead to improved lifestyles. Rural and small town residents are often challenged in making their case for public transportation improvements because their problems do not seem as significant as those of urban areas. Public transportation is a remedy to this situation as it would offer dependable alternatives and act as a connector between all the central areas. It is the determination of purpose and need that leads to agency exploration of suitable transportation responses. The public entities expected to recognize and address the gap between need and available transit service are the MPOs and COGs. These agencies require the assessment of purpose and need as a starting point to address mobility gaps. The year 5 research will assemble findings from all previous years to present the perspective of vulnerability proximate to each Texas Megaregion corridor. The research findings are designed to assist decision making by providing an assessment tool to identify the location of vulnerable populations and determine the travel needs that can be met in the megaregion -- outside traditional jurisdictional boundaries.]]></description>
      <pubDate>Sat, 02 Oct 2021 15:53:49 GMT</pubDate>
      <guid>https://rip.trb.org/View/1881790</guid>
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    <item>
      <title>An Alternative Approach to Analyzing Demand Potential for Travel by High Speed Rail in the Texas Triangle</title>
      <link>https://rip.trb.org/View/1517609</link>
      <description><![CDATA[Existing studies on high-speed rail (HSR) demand analysis in the United States mostly rely on the conventional procedure of four-step travel demand modeling with data assembled from constituent metropolitan planning organizations (MPOs) along the proposed HSR routes. This approach likely produces forecasting outcomes favored towards business-as-usual, car-dominated trends given that HSR has never existed in modern times in US megaregions. The proposed project explores an alternative approach to analyzing aggregate mobility demand for high-speed travel in the Texas Triangle megaregion, simulating shares of HSR modes under different transportation policy assumptions, and drawing implications for long term strategic infrastructure investments in the Texas Triangle. The project plans to carry out five tasks. Task 1 reviews the literature related to HSR studies and travel demand analyses for non-existent travel options. Literature on modal competition and complementarity among air, HSR, and telecommunications will also be reviewed. Task 2 assembles data on 1) inter-metropolitan travel by air and surface transportation from such sources as Bureau of Transportation Statistics and National Household Travel Surveys, and 2) projections of population growth and economy/income changes for up to the year of 2050 at the county-level in the Texas Triangle. Task 3 calibrates an aggregate model of mobility demand as a function of population, economy, income, and travel time-/travel money budgets. Task 4 estimates future mobility demand in terms of total person-miles of travel (PMT) as well as HSR shares under different policy scenarios. Task 5 reports analysis results, compares outcomes of different scenarios, and draws implications for long-range infrastructure investments in the Texas Triangle. ]]></description>
      <pubDate>Fri, 29 Jun 2018 12:26:16 GMT</pubDate>
      <guid>https://rip.trb.org/View/1517609</guid>
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    <item>
      <title>Equitable access to transit within and across megaregions</title>
      <link>https://rip.trb.org/View/1489041</link>
      <description><![CDATA[There is increasing concern about equitable access to transit within, and cross,
megaregions and what this means for access to jobs, amenities, and live in economically and racially diverse neighborhoods. The average household in the United States spends more on transportation than on any budget item aside from housing. How much they spend is strongly influenced by where they live. In many cases, cheaper housing is, by virtue of its location, offset by more expensive transportation. Concerns about location affordability date back decades, but have been gathering steam in recent years.  In this project, the research teams explore how housing and transportation costs, and transportation time, varies by income and race across the nation, and then within three megaregions: Northeast (Boston‐Washington); the Texas Triangle; and Cascadia (Seattle‐Portland).  Together, these three megaregions house a quarter of the national population, and all three regions are witnessing increased housing market pressures which raise important concerns about equitable access to transit. In this project, the team first looks at housing and transportation costs across race and income, and within and across cities and megaregions. Next, the team explores concerns that headlong efforts to integrate location affordability criteria into the siting of new affordable housing risk a collision with fair housing goals and overall access to higher opportunity areas. In essence, the team seeks to answer a simple empirical question: is incorporating location affordability into the siting of new subsidized housing projects tantamount to steering such developments into predominantly African American and Latino neighborhoods? Furthermore, does the answer vary across metropolitan regions, perhaps conditioned by differing spatial patterns of racial and ethnic segregation, housing costs, and transportation infrastructure? Finally, could the goal of decreasing transportation costs reduce a household’s ability to access amenities that directly affect household outcomes within and across markets. Combined these questions explore important equity implications for both including transportation costs into housing goals and vice versa, and provides an important means for exploring the prevalence of transit desserts issues of transportation justice within and across regions. The team asks these questions at a national scale, and then focuses on three megaregions: Northeast (Boston‐Washington); the Texas Triangle (Dallas‐Houston‐San Antonio); and Cascadia (Seattle‐Portland). These megaregions each provide unique venues to explore the relationship between transportation and housing costs. The Northeast represents a series of high cost cities where market pressures and gentrification are pushing low‐income households further from the center of cities and into suburbs or neighboring towns. The Texas Triangle region is home to Dallas, which recently was engaged in a significant fair housing lawsuit, and the subsequent court mandate to affirmatively further fair housing has led to an active debate about when and how to incorporate transit into housing decisions. Finally, Cascadia represents an area where poverty rates have decreased, but the cost of both transportation and housing have increased dramatically, affecting where people live and how they access jobs, schools, etc. Combined these three mega‐regions offer unique lens to explore issues of transportation equity, and the whether and how transportation and housing policies can address these issues.
]]></description>
      <pubDate>Thu, 16 Nov 2017 12:37:28 GMT</pubDate>
      <guid>https://rip.trb.org/View/1489041</guid>
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