Dallas-Fort Worth Metropolitan Area Research Articles

On investigating the potential effects of private autonomous vehicle use on home/work relocations and commute times

The current study is motivated by the need to better understand the potential impacts that vehicular automation may have on individual decisions of residential and work relocation in a future autonomous vehicle (AV) scenario. The study employs a multivariate approach to model five behavioral dimensions simultaneously: (1) technology-savviness (TS) propensity, (2) interest in productive use of travel time (IPTT) propensity, (3) interest in work relocation, (4) interest in residential relocation, and (5) tolerance to an increase in commute travel time. Data from a web-based survey of commuters in 2017 in the Dallas-Fort Worth Metropolitan Area (DFW) is employed. The results show that both TS and IPTT, as well as demographic variables, impact relocation decisions when individuals have a private AV available for their commute. Importantly, there is considerable heterogeneity across individuals in the willingness to relocate and/or accept longer commute times in an AV future. As such, our model results may be used to inform inputs to land use and travel demand models in an AV future. Also, our results suggest that the magnitude of value of travel time savings (VTTS) decrease considered in many earlier AV impact simulation studies may be much higher than reality. Relative to 50% and even 100% VTTS decreases assumed in many studies, our results suggest a much more modest 30% or so overall decrease in VTTS because of the ability to commute in a privately-owned AV. Finally, our results do predict a rather substantial extent of urban sprawl due to AVs, potentially up to a 68% increase in the horizontal spread of cities such as Dallas-Fort Worth, unless proactive planning and policies are implemented to avert such consequences of AVs.

Impact of energy production in the Barnett Shale gas region on the measured ambient hydrocarbon concentrations in Denton, Texas

The Barnett Shale play in North Texas is one of the largest active onshore shale gas regions in the United States. Over the past two decades, unconventional energy production from shale gas in North Texas has grown rapidly. The energy production peaked in 2012 and has declined since. The city of Denton is located at the edge of the Barnett Shale play and is within the Dallas-Fort Worth metropolitan area. In this paper, we describe a long-term trend study of 84 total non-methane organic carbon (TNMOC) species measured at the Denton Airport South monitoring station, an exurban site. The annual mean TNMOC concentrations measured during 2000–2017 increased by +8.03 ± 12.92 ppb-C/year (+12.75%/year). The year-to-year increase in the mean TNMOC concentrations mirrored the energy production volume changes from natural gas wells and liquid condensate facilities within 2-km from the ambient air quality monitoring station. Concentrations of alkanes increased significantly, especially the natural gas species of ethane, propane, n-butane, and isobutane. The annual variations in the ethane concentrations were similar to changes observed in the natural gas and liquid condensate production from nearby wells. High levels of ethane, a dominant natural gas species, were originating from regions with a higher density of gas wells within close proximity of the monitoring site. In contrast, the concentrations of alkene and aromatic species have declined during the study period as a result of decreases from traditional urban emission sources. However, the trend in benzene, a carcinogenic aromatic species found in vehicular and natural gas emissions, and xylene concentrations were similar to the n-alkane trend, suggesting the influence of energy production activities on key ambient aromatic compounds.

Urban Trees Are Sinks for Soot: Elemental Carbon Accumulation by Two Widespread Oak Species.

Urban trees could represent important short- and long-term landscape sinks for elemental carbon (EC). Therefore, we quantified foliar EC accumulation by two widespread oak tree species-Quercus stellata (post oak) and Quercus virginiana (live oak)-as well as leaf litterfall EC flux to soil from April 2017 to March 2018 in the City of Denton, Texas, within the Dallas-Fort Worth metropolitan area. Post oak trees accumulated 1.9-fold more EC (299 ± 45 mg EC m-2 canopy yr-1) compared to live oak trees (160 ± 31 mg EC m-2 canopy yr-1). However, in the fall, these oak species converged in their EC accumulation rates, with ∼70% of annual accumulation occurring during fall and on leaf surfaces. The flux of EC to the ground via leaf litterfall mirrored leaf-fall patterns, with post oaks and live oaks delivering ∼60% of annual leaf litterfall EC in fall and early spring, respectively. We estimate that post oak and live oak trees in this urban ecosystem potentially accumulate 3.5 t EC yr-1, equivalent to ∼32% of annual vehicular EC emissions from the city. Thus, city trees are significant sinks for EC and represent potential avenues for climate and air quality mitigation in urban areas.

Injection‐Induced Seismicity and Fault‐Slip Potential in the Fort Worth Basin, Texas

Abstract The rate of seismicity in the hydrocarbon‐producing Fort Worth Basin of north‐central Texas, which underlies the Dallas–Fort Worth metropolitan area, increased markedly from 2008 through 2015, coinciding spatiotemporally with injection of 2 billion barrels of wastewater into deep aquifers. Although the rate of seismicity has declined with injection rates, some earthquake sequences remained active in 2018 and new clusters have developed. Most of this seismicity occurred away from regionally mapped faults, challenging efforts to constrain the continuing hazards of injection‐induced seismicity in the basin. Here, we present detailed new models of potentially seismogenic faults and the stress field, which we use to build a probabilistic assessment of fault‐slip potential. Our new fault map, based on reflection seismic data, tens of thousands of well logs, and outcrop characterization, includes 251 basement‐rooted normal faults that strike dominantly north‐northeast, several of which extend under populated areas. The updated stress map indicates a relatively consistent north‐northeast–south‐southwest azimuth of the maximum horizontal principal stress over seismically active parts of the basin, with a transition from strike‐slip faulting in the north to normal faulting in the southeast. Based on these new data, our probabilistic analysis shows that a majority of the total trace length of the mapped faults have slip potential that is equal to or higher than that of the faults that have already hosted injection‐induced earthquake sequences. We conclude that most faults in the system are highly sensitive to reactivation, and we postulate that many faults are still unidentified. Ongoing injection operations in the region should be conducted with these understandings in mind.

Do rail transit stations affect housing value changes? The Dallas Fort-Worth metropolitan area case and implications

Dependency on the automobile in the United States has been associated with many urban problems. As a result, many American cities have seen a rebound in public transportation systems—many of whom have built modern rail transit systems. This resurgence of rail transit systems has caused apparent shifts in economic, social, and spatial aspects of neighborhoods located in proximity to rail stations.This study investigates the changes in housing value between 2000 and 2014 in 454 block groups within a one-mile buffer around rail stations located in the Dallas-Fort Worth metropolitan area to determine if there is a correlation between proximity to rail stations and median housing value. This study uses two approaches to analyze the data. First, a comparison of changes in housing value within block groups located in the study area during the study period is introduced. Next, an innovative approach is employed to select the best regression model using the data on the block groups located within the study area to understand the relationships between the selected independent variables and the changes in housing value during the study period in relation to the research question.The findings demonstrate that economic development and commercial activity locations have the highest effect on housing value during the study period, and block groups that were closer to rail stations experienced lower changes in housing value compared to block groups located farther away from stations. An interesting finding contrary to some of the literature is that an increase in the percent of the black population does not have negative effects on the change in property values. The findings for Hispanic and other minorities is also the same. These findings are a useful addition to the existing literature and contribute to the field of urban planning to mitigate the effects on housing value surrounding station areas. In addition, planners and policymakers could use the implications from the findings to adopt some policies for furthering the success of rail transit systems in urban areas by sustaining station area development.

Investigating objective and subjective factors influencing the adoption, frequency, and characteristics of ride-hailing trips

Even as ride-hailing has become ubiquitous in most urban areas, its impacts on individual travel are still unclear. This includes limited knowledge of demand characteristics (especially for pooled rides), travel modes being substituted, types of activities being accessed, as well as possible trip induction effects. The current study contributes to this knowledge gap by investigating ride-hailing experience, frequency, and trip characteristics through two multi-dimensional models estimated using data from the Dallas-Fort Worth Metropolitan Area. Ride-hailing adoption and usage are modeled as functions of unobserved lifestyle stochastic latent constructs, observed transportation-related choices, and sociodemographic variables. The results point to low residential location density and people’s privacy concerns as the main deterrents to pooled ride-hailing adoption, with non-Hispanic Whites being more privacy sensitive than individuals of other ethnicities. Further, our results suggest a need for policies that discourage the substitution of short-distance “walkable” trips by ride-hailing, and a need for low cost and well-integrated multi-modal systems to avoid substitution of transit trips by this mode.

Evaluating the relationship between rail transit and industrial agglomeration: An observation from the Dallas-fort worth region, TX

Recent studies have suggested that rail transit not only facilitates urban growth but also promotes urban agglomeration. Yet research that links industrial agglomeration with rail transit is scant—what types of industries are likely to cluster near rail stations? To what extent can rail transit access be seen as having an influence on industrial agglomeration? And how do these interactions vary as rail transit proximity increases? To answer these and related questions, we investigate the relationship between industrial agglomeration and rail transit in the Dallas-Fort Worth metropolitan area using the Longitudinal Employer Dynamics (LEHD) employment data from 2014 at the census block level. First, we use the Local Indicator of Spatial Association statistics (LISA) tests to identify industrial agglomeration patterns within the study area. We then use logistics models to reveal the relationship between rail transit proximity and industrial agglomeration. Our study finds that the impacts of rail transit on industrial agglomeration, in terms of magnitudes and signs, are mixed across industries. The varying results suggest that the benefits of rail transit access exhibit considerable demand from certain industry sectors including the manufacturing, knowledge, and services industries, while exerting weaker forces in pulling agglomeration in its immediate environs among other industries (including the retail trade sector). In practice, these results are useful for justifying evidence-based rail transit planning.

Measuring sounds with a grid method with examining public spaces

This study provides an outlook of the association between sound and public space by performing sound level meter in Dallas Fort-Worth metropolitan area. The main research question of the study is that whether the characteristics (program elements, position of public spaces and roads, and public space usage in different time intervals) of the public open spaces have relationship with sound levels. In order to demonstrate it, the applied sound level meter instruments for sound environment in public open spaces by using grid method. This study recommends that time intervals have effects on sound and practice should concentrate for this essential element. At this point, sound is forgotten component and it is not paid attention by urban planners, architects, landscape architects, civil engineering and many other disciplines. Presently, there are a few studies that are related to sound relationships in the United States. Hence, this research illustrates a point of view of a sound research for rapid growing urba...

Entering the public sphere: the citizenship practices of US immigrants

This paper originally delivered as a keynote speech at the Turkish Migration Conference 2015 in Prague, Czech Republic on June 25, 2015. It focuses on civic engagementi political participation and citizenship practices of Asian Indians in Dallas Fort Worth Metropolitan area drawing on qualitative field research material. Community participation is a process. Embedded in this observation is an understanding that as the individual branches out, he or she is becoming involved with associations with great civic and/or political presence, moving from one community of practice to another, and from a peripheral position to one of greater participation to invoke the ideas of Lave and Wenger. But equally, these activities illustrate how new immigrants construct their own sense of belonging as they engage with and interpret what it means to be an American and what kind of an American they want to be.

Incidence of West Nile virus infection in the Dallas-Fort Worth metropolitan area during the 2012 epidemic.

The 2012 West Nile virus (WNV) epidemic was the largest since 2003 and the North Texas region was the most heavily impacted. We conducted a serosurvey of blood donors from four counties in the Dallas-Fort Worth area to characterize the epidemic. Blood donor specimens collected in November 2012 were tested for WNV-specific antibodies. Donors positive for WNV-specific IgG, IgM, and neutralizing antibodies were considered to have been infected in 2012. This number was adjusted using a multi-step process that accounted for timing of IgM seroreversion determined from previous longitudinal studies of WNV-infected donors. Of 4971 donations screened, 139 (2·8%) were confirmed WNV IgG positive, and 69 (1·4%) had IgM indicating infection in 2012. After adjusting for timing of sampling and potential seroreversion, we estimated that 1·8% [95% confidence interval (CI) 1·5-2·2] of the adult population in the Dallas-Fort Worth area were infected during 2012. The resulting overall estimate for the ratio of infections to reported WNV neuroinvasive disease (WNND) cases was 238:1 (95% CI 192-290), with significantly increased risk of WNND in older age groups. These findings were very similar to previous estimates of infections per WNND case, indicating no change in virulence as WNV evolved into an endemic infection in the United States.

Energy Boom and Gloom? Local Effects of Oil and Natural Gas Drilling on Subjective Well-Being

The United States experienced a considerable increase in oil and natural gas extraction in recent years due to technological advancements including horizontal drilling and hydraulic fracturing. Increased energy development likely creates both benefits and costs, but the net effects for local residents are not well understood. This paper examines effects of conventional and horizontal oil and natural gas drilling in Texas on subjective assessments of life-satisfaction and bad mental health days for nearby residents. Horizontal drilling has statistically significant deleterious effects on well-being, but the effects are driven by the Dallas-Fort Worth (DFW) metropolitan area, an area with both very high levels of horizontal drilling and a large urban population.

The other end of the spectrum: municipal climate change mitigation planning in the politically conservative Dallas–Fort Worth region

Among the growing number of studies describing and evaluating municipal-scale programs to mitigate global climate change, relatively little attention has been given to municipalities that are not leading such efforts or to municipalities in politically conservative regions. Our research examines climate-relevant municipal planning in a structured sample of communities across the largely conservative Dallas–Fort Worth metropolitan area. Using data from planning documents and staff interviews, we evaluate the prevalence and vigor of numerous mitigation-relevant activities. We characterize the target municipalities according to a new typology addressing the maturation of local climate action. We find that in this politically conservative region communities are clustered toward the laggard end of the typology—away from the advanced end—and for the first time in the climate planning literature we identify several faltering emergent communities, whose nascent climate protection initiatives appear to have stalled.

Representations of everyday travel experiences: Case study of the Dallas-Fort Worth Metropolitan Area

Disparity of access to transportation also affects access to essential urban resources, particularly for lower income populations and minorities. Studies have shown how current transportation planning practices are dominated by the notion of planners as experts that produce the knowledge of future transportation needs using a series of analytical steps and computer modeling. Consequently, existing practices such as transport modeling perpetuate barriers to mobility and lack of accessibility, and therefore, there is a need to make explicit how these existing practices exclude particular population groups. Using the Dallas-Fort Worth (DFW) Metropolitan Area as a case study, this paper makes a stronger connection between the assumptions planners make regarding transportation needs and goals with everyday travel experiences of a variety of residents. This research utilizes travel diaries to provide in-depth understandings of individual’s travel experiences from various neighborhoods in the DFW Region to understand how differences in mobility and accessibility affect access to places.

Effects of urbanization and climate change on stream health in north-central Texas.

Estimation of stream health involves the analysis of changes in aquatic species, riparian vegetation, microinvertebrates, and channel degradation due to hydrologic changes occurring from anthropogenic activities. In this study, we quantified stream health changes arising from urbanization and climate change using a combination of the widely accepted Indicators of Hydrologic Alteration (IHA) and Dundee Hydrologic Regime Assessment Method (DHRAM) on a rapidly urbanized watershed in the Dallas-Fort Worth metropolitan area in Texas. Historical flow data were split into pre-alteration and post-alteration periods. The influence of climate change on stream health was analyzed by dividing the precipitation data into three groups of dry, average, and wet conditions based on recorded annual precipitation. Hydrologic indicators were evaluated for all three of the climate scenarios to estimate the stream health changes brought about by climate change. The effect of urbanization on stream health was analyzed for a specific subwatershed where urbanization occurred dramatically but no stream flow data were available using the widely used watershed-scale Soil and Water Assessment Tool (SWAT) model. The results of this study identify negative impacts to stream health with increasing urbanization and indicate that dry weather has more impact on stream health than wet weather. The IHA-DHRAM approach and SWAT model prove to be useful tools to estimate stream health at the watershed scale.

The Urban Heat Island of the North-Central Texas Region and Its Relation to the 2011 Severe Texas Drought

AbstractHourly surface temperature differences between Dallas–Fort Worth, Texas, metropolitan and rural sites have been used to calculate the urban heat island from 2001 to 2011. The heat island peaked after sunset and was particularly strong during the drought and heat wave in July 2011, reaching a single-day instantaneous maximum value of 5.4°C and a monthly mean maximum of 3.4°C, as compared with the 2001–11 July average of 2.4°C. This severe drought caused faster warming of rural locations relative to the metropolitan area in the morning as a result of lower soil moisture content, which led to an average negative heat island in July 2011 of −2.3°C at 1100 central standard time. The ground-based assessment of canopy air temperature at screening level has been supported by a remotely sensed surface estimate from the Moderate Resolution Imaging Spectroradiometer (MODIS) on board theTerrasatellite, highlighting a dual-peak maximum heat island in the major city centers of Dallas and Fort Worth. Both ground-based and remotely sensed spatial analyses of the maximum heat island indicate a northwest shift, the result of southeast winds in July 2011 of ~2 m s−1on average. There was an overall positive trend in the urban heat island of 0.14°C decade−1in the Dallas–Fort Worth metropolitan area from 2001 to 2011, due to rapid urbanization. Superimposed on this trend are significant interannual and decadal variations that influence the urban climate.

Rule of Capture and Urban Sprawl: A Potential Federal Financial Risk in Groundwater-Dependent Areas

This paper illustrates the potential federal financial risk created by groundwater overabstraction, rapid urbanization, competing economic interests, and institutional arrangements in groundwater-dependent areas of Texas. In the Upper Trinity Groundwater Conservation District, located in the Dallas–Fort Worth metropolitan area, urban sprawl creates suburbanized rural areas reliant upon the Upper Trinity Aquifer. In the past 10 years, competition of economic interests for groundwater has intensified, as the area has experienced rapid urban sprawl combined with escalating Barnett Shale hydraulic fracturing activity, which coincided with two extreme droughts in 2006 and 2011. Urban sprawl generates business opportunities and tax revenues for state and local governments in the short term, but if groundwater overabstraction leads to land subsidence, financial risk is transferred to the federal government through increased risk exposure from federal housing loans and government-backed residential lending.

Relationships between benthic macroinvertebrate community structure and geospatial habitat, in‐stream water chemistry, and surfactants in the effluent‐dominated Trinity River, Texas, USA

Over the past 20 years, benthic macroinvertebrate community structure studies have been conducted on the upper Trinity River, Texas, USA, which is dominated by municipal wastewater treatment plant (WWTP) and industrial effluents. The Trinity River is located in the Dallas-Fort Worth metropolitan area, and is the most highly populated and industrialized watershed in Texas. As such, the Trinity River represents a near-worst-case scenario to examine the environmental effects of domestic-municipal and industrial effluents on aquatic life. A 1987 to 1988 study concluded that many stretches of the river supported a diverse benthic community structure; however, a decline in taxa richness occurred immediately downstream of WWTPs. A 2005 study designed to parallel the 1987 to 1988 efforts evaluated how changes in water quality, habitat, and increased urbanization impacted benthic community structure. Physicochemical measurements, habitat quality, geospatial variables, and benthic macroinvertebrates were collected from 10 sites. Surfactants were measured and toxic units (TUs) were calculated for surface water and pore water as indicators of domestic/household use of cleaning products. Total TUs indicated a low potential for biological impacts. Toxic unit distribution was not dependent on WWTP location and did not correlate with any benthic variable. Eight environmental parameters were determined to be useful for predicting changes in benthic macroinvertebrate community structure: surfactant surface water TUs (SWTU), in-stream habitat cover, and surface water total organic carbon were the top three parameters. Abundance, taxa richness, and taxa similarity in 2005 had increased since the earlier study throughout the immediate vicinity of the metropolitan area.

LIVED HYBRIDITY: SECOND-GENERATION IDENTITY CONSTRUCTION THROUGH COLLEGE FESTIVAL

Recent research suggests that the children of recent immigrants, the so-called second generation, no longer choose to emphasize one identity over the other but that their identities are more fluid and multifaceted. College campuses are often the arenas in which a new hybrid identity develops. This article addresses how South Asian American college students make sense of and control their various identities through the celebration of Diwali, an event sponsored each year by the Indian Students Association (ISA) on a college campus in the Dallas-Fort Worth metropolitan area. South Asian students use performative space to help them make sense of their backgrounds in ways that both differentiate them from and allow for association with the majority student population. They also use this space as a safe place for “coming out,” that is, for communicating their hybrid identity to their parents. This hybrid identity is expressed through a discourse of “brownness” that marks something distinctive and that reflects the process by which the children of immigrants choose among a range of identities to create integrated selves. The campus Diwali festival is the expression of those selves.

Use of watershed factors to predict consumer surfactant risk, water quality, and habitat quality in the upper Trinity River, Texas

Surfactants are high production volume chemicals that are used in a wide assortment of “down-the-drain” consumer products. Wastewater treatment plants (WWTPs) generally remove 85 to more than 99% of all surfactants from influents, but residual concentrations are discharged into receiving waters via wastewater treatment plant effluents. The Trinity River that flows through the Dallas–Fort Worth metropolitan area, Texas, is an ideal study site for surfactants due to the high ratio of wastewater treatment plant effluent to river flow (> 95%) during late summer months, providing an interesting scenario for surfactant loading into the environment. The objective of this project was to determine whether surfactant concentrations, expressed as toxic units, in-stream water quality, and aquatic habitat in the upper Trinity River could be predicted based on easily accessible watershed characteristics. Surface water and pore water samples were collected in late summer 2005 at 11 sites on the Trinity River in and around the Dallas–Fort Worth metropolitan area. Effluents of 4 major waste water treatment plants that discharge effluents into the Trinity River were also sampled. General chemistries and individual surfactant concentrations were determined, and total surfactant toxic units were calculated. GIS models of geospatial, anthropogenic factors (e.g., population density) and natural factors (e.g., soil organic matter) were collected and analyzed according to subwatersheds. Multiple regression analyses using the stepwise maximum R 2 improvement method were performed to develop prediction models of surfactant risk, water quality, and aquatic habitat (dependent variables) using the geospatial parameters (independent variables) that characterized the upper Trinity River watershed. We show that GIS modeling has the potential to be a reliable and inexpensive method of predicting water and habitat quality in the upper Trinity River watershed and perhaps other highly urbanized watersheds in semi-arid regions.

Risk Factors for 30-Day Hospital Readmission in Patients ≥65 Years of Age

The objective of the study was to develop and validate predictors of 30-day hospital readmission using readily available administrative data and to compare prediction models that use alternate comorbidity classifications. A retrospective cohort study was designed; the models were developed in a two-thirds random sample and validated in the remaining one-third sample. The study cohort consisted of 29,292 adults aged 65 or older who were admitted from July 2002 to June 2004 to any of seven acute care hospitals in the Dallas–Fort Worth metropolitan area affiliated with the Baylor Health Care System. Demographic variables (age, sex, race), health system variables (insurance, discharge location, medical vs surgical service), comorbidity (classified by the Elixhauser classification or the High-Risk Diagnoses in the Elderly Scale), and geographic variables (distance from patient's residence to hospital and median income) were assessed by estimating relative risk and risk difference for 30-day readmission. Population-attributable risk was calculated. Results showed that age 75 or older, male sex, African American race, medical vs surgical service, Medicare with no other insurance, discharge to a skilled nursing facility, and specific comorbidities predicted 30-day readmission. Models with demographic, health system, and either comorbidity classification covariates performed similarly, with modest discrimination (C statistic, 0.65) and acceptable calibration (Hosmer-Lemeshow ϰ2 = 6.08; P > 0.24). Models with demographic variables, health system variables, and number of comorbid conditions also performed adequately. Discharge to long-term care (relative risk, 1.94; 95% confidence interval, 1.80–2.09) had the highest population-attributable risk of 30-day readmission (12.86%). A 25% threshold of predicted probability of 30-day readmission identified 4.1% of patients ≥65 years old as priority patients for improved discharge planning. We conclude that elders with a high risk of 30-day hospital readmission can be identified early in their hospital course.