Spatial Access Research Articles

The Spatial Context of Food Assistance: Examining Local Food Assistance Environment in the Context of SNAP

ABSTRACT We develop the concept of the local food assistance environment to examine how spatial access to different local food assistance resources might shape food assistance program participation. Using unique survey data capturing Supplemental Nutrition Assistance Program (SNAP) participation in metropolitan Detroit, we explore how spatial access to local food assistance resources (e.g., SNAP offices, food retailers, charitable food assistance programs) may be associated with SNAP receipt. Descriptive analyses find that closer proximity to food assistance resources and retailers who accept food assistance benefits is positively associated with self-reported SNAP receipt.

Changes in methadone take-home dosing before and after COVID-19

IntroductionIn response to the COVID-19 pandemic, a federal exemption allowed stable and less stable patients greater take-home doses of methadone. We assessed the adoption of increased take-home medication during COVID-19 and whether increased take-home doses is associated with clients' characteristics. MethodologyWe completed a pre-post study of adults receiving methadone for OUD from an OTP in Spokane, Washington. Our outcome was the change in the number of take-home methadone doses three months before and three months after the March 2020 take-home medication exemption. Clients' characteristics included age, gender, ethnicity, education level, homelessness, spatial access to the clinic, and methamphetamine use. ResultsThe study included 194 clients in treatment for a median of three years. All study participants experienced an average increase in take-home medication of 41.4 in the three-month period after the COVID-19 exemption. In the final adjusted models, clients who reported using methamphetamine in the last 30 days experienced a significantly larger increase in take-home dosage (55.6 days) compare to clients who did not use methamphetamine (p ≤0.001). Most of the clients who reported using methamphetamine were also likely to be homeless. All other variables were not associated with a change in take-home doses. ConclusionThese results suggest that the Spokane OTP quickly expanded take-home medication dosing in response to the COVID-19 exemption and broadly expanded take-home dosing among established clients. Clients with concurrent methamphetamine use were allowed fewer take-home doses prior to COVID-19, but after the exemption the clinic provided them the same number of take-home doses as clients who had not used methamphetamine.

Measuring spatial access to the recovery networks for WEEE: An in-depth analysis of the Italian case

The regulation of Waste Electrical and Electronic Equipment (WEEE) industry is of priority importance in the environmental and circular economy agenda of the EU. Within the EU legislation, the Member States must undertake appropriate policies to increase the amount of waste reintroduced in the supply chain. To this end, as the literature suggests, the design of adequate collection infrastructures and geographical proximity to dedicated facilities, named Collection Centers (CCs), are key factors affecting users' willingness to deliver WEEE. In this work, we propose a systematic approach to evaluate the users’ spatial access to WEEE networks. Specifically, we introduce a dashboard of quantitative indicators to assess the presence of sufficient CCs for the take-back service given the demand in a given area (availability) and at measuring the proximity between consumers and CCs (accessibility). We perform an extensive application to the Italian case, which proves the capability of the proposed indicators to: (i) allow comparative analysis among different areas of the country; (ii) shed light on the impact of spatial dimensions on the amount of collected waste; (iii) support decisions concerning the optimal location of new CCs. In this latter regard, we also discuss, formalize and test possible strategies for expanding the network.

Measuring spatial access to emergency general surgery services: does the method matter?

Measuring spatial access to emergency general surgery services: does the method matter?

Spatial, Temporal, and Transit Access to Emergency Food Providers

This research brings together concerns of food environments, food insecurity, and food access to demonstrate four measures of access for an emergency food provider network. Based on the interacting concerns of accessibility and accommodation, the measures are proximity, segment coverage, transit access, and transit time. Proximity measures geographic access, whereas segment coverage focuses on access at different times of the day, on different days of the week, during different weeks of the month. The two transit measures use the region’s actual transit network scheduling to address space–time access via transit. The measures are applied to the food pantry network of Cuyahoga County, Ohio. Each demonstrates a unique nuance of access in the emergency food provider context, providing useful inputs into the process of meeting a community’s emergency food needs.

An open software environment to make spatial access metrics more accessible

An open software environment to make spatial access metrics more accessible

Precoded Spatial Modulation-Aided Cooperative NOMA

In this letter, a precoded spatial modulation-aided cooperative nonorthogonal multiple access (NOMA), referred to as PC-NOMA, has been proposed for multiple-input and multiple-output (MIMO) downlink scenario. In PC-NOMA scheme, the base station (BS) broadcasts three users' information over two time slots: in the first slot, the two near users receive data through direct links and in the second slot, the third user (far) receives data indirectly from the near users. The precoded direct links' signal has been superposed with indirect link's signal in broadcast phase at the BS. The indirect link's signal has been decoded and forwarded at the direct link's user using the successive-interference cancellation (SIC) method in cooperative phase. The symbol error rate (SER) and mutual information (MI) under inter-users interference (IUI) have been derived for the proposed PC-NOMA. The impact of various system parameters, such as the number of transmitting and receiving antennas, have been analyzed for the proposed PC-NOMA.

Measuring geospatial healthcare access to primary level facilities in Mexico: a GIS-based diagnosis analysis.

To describe a general overview of health services delivery in Mexico and geospatially analyze the current distribution and accessibility of Primary Health Care (PHC) facilities to contribute to new approaches to improve healthcare planning in Mexico. We performed a spatial analysis of official data to analyze current distances from health facilities to population, to determine the underserved areas of health services delivery in three selected states using a ranking of indicators. We estimated service area coverage of PHC facilities with road networks of three Mexican states (Chiapas, Guerrero, and Oaxaca). Our estimations provide an overview of spatial access to healthcare of the Mexican population in Mexico's three most impoverished states. We did not consider social security nor private providers. Geospatial access to health facilities is critical to achieving PHC and adequate coverage. Countries like Mexico must measure this to identify underserved areas with a lack of geospatial access to healthcare to solve it. This type of analysis provides critical information to help decision-makers decide where to build new health facilities to increase effective geospatial access to care and to achieve Universal Health Coverage.

Modelling geographical accessibility to urban centres in Kenya in 2019.

BackgroundAccess to major services, often located in urban centres, is key to the realisation of numerous Sustainable Development Goals (SDGs). In Kenya, there are no up-to-date and localised estimates of spatial access to urban centres. We estimate the travel time to urban centres and identify marginalised populations for prioritisation and targeting.MethodsUrban centres were mapped from the 2019 Kenya population census and combined with spatial databases of road networks, elevation, land use and travel barriers within a cost-friction algorithm to compute travel time. Seven travel scenarios were considered: i) walking only (least optimistic), ii) bicycle only, iii) motorcycle only, iv) vehicle only (most optimistic), v) walking followed by motorcycle transport, vi) walking followed by vehicle transport, and vii) walking followed by motorcycle and then vehicle transport (most pragmatic). Mean travel time, and proportion of the population within 1-hour and 2-hours of the urban centres were summarized at sub-national units (counties) used for devolved planning. Inequities were explored and correlations between the proportion of the population within 1-hour of an urban centre and ten SDG indicators were computed.ResultsA total of 307 urban centres were digitised. Nationally, the mean travel time was 4.5-hours for the walking-only scenario, 1.0-hours for the vehicle only (most optimistic) scenario and 1.5-hours for the walking-motorcycle-vehicle (most pragmatic) scenario. Forty-five per cent (21.3 million people) and 87% (41.6 million people) of Kenya’s population resided within 1-hour of the nearest urban centre for the least optimistic and most pragmatic scenarios respectively. Over 3.2 million people were considered marginalised or living outside the 2-hour threshold in the pragmatic scenario, 16.0 million Kenyans for walking only, and 2.2 million for the most optimistic scenario. County-level spatial access was highly heterogeneous ranging between 8%-100% and 32%-100% of people within the 1-hour threshold for the least and most optimistic scenarios, respectively. Counties in northern and eastern parts of Kenya were generally most marginalised. The correlation coefficients for nine SDG indicators ranged between 0.45 to 0.78 and were statistically significant.ConclusionTravel time to urban centres in Kenya is heterogeneous. Therefore, marginalised populations should be prioritised during resource allocation and policies should be formulated to enhance equitable access to public services and opportunities in urban areas.

The relationship between spatial access and modern contraceptive use: is proximity to a healthcare facility a determinant of use among women in Kinshasa, DRC?

Background: Spatial access has a direct effect on health service utilization in many settings. Distance to health facility has proven to affect family planning (FP) service use in many Sub-Saharan countries. Studies show that women who reside closer to facilities offering family planning services are more likely to use modern contraceptives. However, researchers often test the theory of distance decay. This study analyzed the significance of proximity to family planning services, service availability, and quality of family planning services on modern contraceptive use in Kinshasa, Democratic Republic of the Congo. Methods: We used a pool of four rounds of facility- and population-based survey data in Kinshasa from PMA2020 between 2014 and 2016. We used GPS coordinates to calculate the distance between the health facilities and households. We tested if women who live closer to service delivery points with higher level of availability and quality are more likely to use modern contraceptives or less likely to have unmet need for contraceptive services. Results: 10,968 women were interviewed over four rounds of data collection. Our findings show that living closer to an SDP is not a determinant of modern contraceptive use or having unmet need for FP services. Lack of cognitive access, economic barriers, bypassing the closest facility, and sociocultural norms are strong barriers for women in Kinshasa to use modern contraceptives. Proximity to quality services did not necessarily result in increased FP use among women of reproductive age living in Kinshasa, thus suggesting that a bypass phenomenon may occur when obtaining modern contraceptive services. Conclusions: This study notes that barriers other than proximity to access may be substantial determinants of contraceptive use or unmet need. More research should be conducted that directly measures multidimensional components of access in order to interpret women’s contraceptive seeking behaviors in urban areas of Sub-Saharan Africa.

Is the severity of the Great Recession's aftershocks correlated with changes in access to the combined prevention environment among people who inject drugs?

BackgroundThe 2008 Recession was a global event that led to funding cuts for programs and services in the United States; though this recession officially ended in 2009, its aftershocks continued through 2012. We evaluated the relationship between the severity of the Great Recession's aftermath and spatial access to combined prevention services (i.e. HIV testing, syringe service programs, substance use disorder treatment program) for people who inject drugs (PWID) living in 19 metropolitan statistical areas (MSAs) in the United States. MethodsThe unit of analysis was the ZIP code; we sampled ZIP codes in these 19 MSAs where ≥1 PWID lived in 2009 and 2012, according to the CDC's National HIV Behavioral Surveillance. We used administrative data to describe the combined prevention environment (i.e., spatial access to HIV testing) for each ZIP code, and measured the severity of the recession's aftermath in each ZIP code, and in the counties and MSAs where these ZIP codes were located. Multilevel modeling estimated associations between changes in the aftermath of the Great Recession and ZIP code-level changes in spatial access to combined prevention services from 2009 to 2012. Results675 ZIP codes located in 36 counties and 19 MSAs were included in this analysis. From 2009 to 2012, 21% of ZIP code areas lost access to combined prevention services and 14% gained access. ZIP codes with higher poverty rates relative to their respective MSAs were less likely to lose access (aOR: 0.91; 95% CI: 0.88, 0.95) and more likely to gain access (aOR: 1.05; 95% CI: 1.01, 1.09); there is some evidence to suggest the former association was attenuated for ZIP codes with higher percentages of non-Hispanic white residents. ConclusionCombined prevention services for PWID living in these 675 ZIP codes demonstrated resilience in the aftermath of the Great Recession. Future research should explore whether community-based and federal HIV prevention initiatives contributed to this resilience, particularly in areas with higher concentrations of people of color.

Influence of the Spatial Distribution of the Transmitters on the Performance of Multi-Packet Reception Wireless Systems

In Multi-Packet Reception (MPR) systems multiple packets transmitted at the same time can be decoded at the receiver. Due to the path loss effect, in MPR communication systems the channel is more likely to be captured by the nearby transmitters, which can lead to unfairness on medium access. In this letter, we study the impact of the spatial distribution of the nodes on the performance of MPR-based PHY-layer systems. The performance of the MPR communication system is addressed by deriving the spatial capture probability and the average number of captured packets when n simultaneous transmissions occur, taking into account the radio propagation effects and the capture capabilities of the communication scheme. Finally, the letter analyses the spatial capture probability for different nodes' locations, network sizes, and nodes' spatial distributions. A comparison between simulated and numerical results confirms the accuracy of the proposed modeling approach and shows how can the network nodes be orchestrated in terms of spatial access to improve the MPR-based PHY-layer performance.

Identifying Hospitals in Nepal for Acute Burn Care and Stabilization Capacity Development: Location-Allocation Modeling for Strategic Service Delivery

In Nepal, preventable death and disability from burn injuries are common due to poor population-level spatial access to organized burn care. Most severe burns are referred to a single facility nationwide, often after suboptimal burn stabilization and/or significant care delay. Therefore, we aimed to identify existing first-level hospitals within Nepal that would optimize population-level access as "burn stabilization points" if their acute burn care capabilities are strengthened. A location-allocation model was created using designated first-level candidate hospitals, a population density grid for Nepal, and road network/travel speed data. Six models (A-F) were developed using cost-distance and network analyses in ArcGIS to identify the three vs five candidate hospitals at ≤2, 6, and 12 travel-hour thresholds that would optimize population-level spatial access. The baseline model demonstrated that currently 20.3% of the national population has access to organized burn care within 2 hours of travel, 37.2% within 6 travel-hours, and 72.6% within 12 travel-hours. If acute burn stabilization capabilities were strengthened, models A to C of three chosen hospitals would increase population-level burn care access to 45.2, 89.4, and 99.8% of the national population at ≤2, 6, and 12 travel-hours, respectively. In models D to F, five chosen hospitals would bring access to 53.4, 95.0, and 99.9% of the national population at ≤2, 6, and 12 travel-hours, respectively. These models demonstrate developing capabilities in three to five hospitals can provide population-level spatial access to acute burn care for most of Nepal's population. Organized efforts to increase burn stabilization points are feasible and imperative to reduce the rates of preventable burn-related death and disability country-wide.

A Blueprint for Diagnosing the Readiness of Human Service Contracts Data for Spatial Access Analysis

Each year, government spends more than a trillion dollars in combined federal, state, and local funds to support hundreds of thousands of local service providers in a highly decentralized system of human service provision in the U.S. – making it hard to gain a bigger picture perspective on whether these combined funds go to where needs are concentrated. In light of the promise of data-driven decision making and government open data, this article provides a blueprint to assess how ready open administrative data are for gaining such a perspective. As the case example, we analyze 2017 open financial contracts data for human services funded by Chicago, Cook County and Illinois to identify spatial access gaps to these services (with funding amounts). We conclude that these data are not yet ready for such an analysis and outline 5 major data gaps, including a lack of data on service site locations and fiduciaries. What we find is that the institutional fragmentation of human services contracting leads to a multitude of disparate data sources, unstandardized data definitions and non-systematic coverage of key information on human services that need to be addressed in order to gain a perspective of where funding goes across departments and jurisdictions. We outline what data elements are still needed to close the identified gaps and point to a spatial access prototype we developed for the Chicago Department of Public Health (CDPH) for new data it collected to address several of these gaps.

Gaining from rational health planning: Spatial reallocation of top-tier general hospital beds in China

The inequity in spatial access to health care among regions remains one of the most persistent challenges faced by countries around the world. This study addressed the problem of maldistribution of top-tier healthcare resources in China via the adoption of rational health planning. We proposed an optimization model to maximize the equity in spatial access by reallocating beds among currently existing top-tier general hospitals in China. The two-step floating catchment area method was employed to measure the spatial accessibility, and quadratic programming with the objective of minimizing the demand-factor-weighted variance of spatial accessibility was used to obtain the optimal quantity of beds in each hospital. The results demonstrated that the reallocation of beds had substantially improved both equity and efficiency of spatial access. The optimized spatial reallocation of beds promoted equity in spatial access with a 52% reduction of the weighted standard deviation, from 1.03 to 0.49, as well as achieving enhanced efficiency represented by a 153% increase in the weighted median spatial access, from 0.15 to 0.38. Our findings are expected to provide implications on spatial allocation of China’s healthcare resources, and the optimization method could be adopted in future evidence-based health planning procedures in order to improve the equitableness of healthcare delivery systems.

Facility Attractiveness and Social Vulnerability Impacts on Spatial Accessibility to Opioid Treatment Programs in South Carolina.

Opioid dependence and opioid-related mortality have been increasing in recent years in the United States. Available and accessible treatments may result in a reduction of opioid-related mortality. This work describes the geographic variation of spatial accessibility to opioid treatment programs (OTPs) and identifies areas with poor access to care in South Carolina. The study develops a new index of access that builds on the two-step floating catchment area (2SFCA) method, and has three dimensions: a facility attractiveness index, defined by services rendered incorporated into the Huff Model; a facility catchment area, defined as a function of facility attractiveness to account for variable catchment size; and a Social Vulnerability Index (SVI) to account for nonspatial factors that mitigate or compound the impacts of spatial access to care. Results of the study indicate a significant variation in access to OTPs statewide. Spatial access to OTPs is low across the entire state except for in a limited number of metropolitan areas. The majority of the population with low access (85%) live in areas with a moderate-to-high levels of social vulnerability. This research provides more realistic estimates of access to care and aims to assist policymakers in better targeting disadvantaged areas for OTP program expansion and resource allocation.

Use of the spatial access ratio to measure geospatial access to emergency general surgery services in California.

Emergency general surgery (EGS) encompasses a spectrum of time-sensitive and resource-intensive conditions, which require adequate and timely access to surgical care. Developing metrics to accurately quantify spatial access to care is critical for this field. We sought to evaluate the ability of the spatial access ratio (SPAR), which incorporates travel time, hospital capacity, and population demand in its ability to measure spatial access to EGS care and delineate disparities. We constructed a geographic information science platform for EGS-capable hospitals in California and mapped population location, race, and socioeconomic characteristics. We compared the SPAR to the shortest travel time model in its ability to identify disparities in spatial access overall and for vulnerable populations. Reduced spatial access was defined as >60 minutes travel time or lowest three classes of SPAR. A total of 283 EGS-capable hospitals were identified, of which 142 (50%) had advanced resources. Using shortest travel time, only 166,950 persons (0.4% of total population) experienced prolonged (>60 minutes) travel time to any EGS-capable hospital, which increased to 1.05 million (2.7%) for advanced-resource centers. Using SPAR, 11.5 million (29.5%) had reduced spatial access to any EGS hospital, and 13.9 million (35.7%) for advanced-resource centers. Rural residents had significantly decreased access for both overall and advanced EGS services when assessed by SPAR despite travel times within the 60-minute threshold. While travel time and SPAR showed similar overall geographic patterns of spatial access to EGS hospitals, SPAR identified a greater a greater proportion of the population as having limited access to care. Nearly one third of California residents experience reduced spatial access to EGS hospitals when assessed by SPAR. Metrics that incorporate measures of population demand and hospital capacity in addition to travel time may be useful when assessing spatial access to surgical services. Cross-sectional study, level VI.

75 Geographic Location-Allocation Modeling to Optimize National Burn Care Delivery and Disaster Planning

Abstract Introduction The study country has a disproportionally high burn incidence rate compared to other low- and middle-income countries. Preventable death and disability are common due to poor population-level spatial access to organized burn care, including no organized system of ground or aeromedical transport. Currently, severe burns are referred to a single facility nationwide, often with suboptimal stabilization and/or significant care delay. Therefore, we aimed to identify existing candidate hospitals that would optimize population-level access to acute burn care if burn stabilization capabilities were strengthened in each hospital. Methods The 175 general hospitals that referred patients to the single national burn referral center between 2016–2020 were designated as candidate hospitals. Demand points for location-allocation modelling were derived from a 2020 estimated population density grid for the country (total population 30,184,338). Road network and national speed limit data were extracted from publicly available geodata to inform travel distance and time. Six models were developed (Models A-F) using cost-distance and network analyses to identify the 3 vs 5 candidate hospitals that would optimize population-level spatial access if their initial burn stabilization capabilities were strengthened. Three travel time thresholds (≤2, 6, and 12 hours) were used for both sets of models. Results Currently, 6,151,298 people (20.3% of the national population) have access to organized burn care within 2 hours of travel, 11,240,957 (37.2%) within 6 hours and 21,925,928 (72.6%) within 12 hours [Table 1]. If acute burn stabilization capabilities were strengthened, Models A-C of 3 chosen hospitals would increase population-level burn care access to 45.2%, 89.4%, and 99.8% of the national population at ≤2, 6, and 12 travel-hours, respectively. Models D-F demonstrated that 5 chosen hospitals would increase population-level burn care access to 53.4%, 95.0%, and 99.9% of national the population at ≤2, 6, and 12 travel-hours, respectively. Conclusions This exercise demonstrates two sets of models for increasing population-level access to acute burn stabilization in the study country. If acute burn stabilization capabilities were strengthened in the identified hospitals, approximately 90% of the national population would have access to burn care within 6 travel-hours in both the 3 and 5 hospital scenarios. Although the models with 5 strengthened hospitals reduce mean travel time, the percent of population with improved travel time access is only marginally higher. Strategic, organized efforts to increase burn stabilization capabilities might reduce the rates of preventable burn-related death and disability country-wide by reducing delays.

Spatial accessibility assessment of COVID-19 patients to healthcare facilities: A case study of Florida

During the COVID-19 pandemic, healthcare facilities worldwide have been overwhelmed by the amount of coronavirus patients needed to be served. Similarly, the U.S. also experienced a shortage of healthcare resources, which led to a reduction in the efficiency of the whole healthcare system. In order to evaluate this from a transportation perspective, it is critical to understand the extent to which healthcare facilities with intensive care unit (ICU) beds are available in both urban and rural areas. As such, this study aims to assess the spatial accessibility of COVID-19 patients to healthcare facilities in the State of Florida. For this purpose, two methods were used: the two-step floating catchment area (2SFCA) and the enhanced two-step floating catchment area (E2SFCA). These methods were applied to identify the high and low access areas in the entire state. Furthermore, a metric, namely the Accessibility Ratio Difference (ARD), was developed to evaluate the spatial access difference between the models. Results revealed that many areas in the northwest and southern Florida have lower access compared to other locations. The residents in central Florida (e.g., Tampa and Orlando cities) had the highest level of accessibility given their higher access ratios. We also observed that the 2SFCA method overestimates the accessibility in the areas with a lower number of ICU beds due to the “equal access” assumption of the population within the catchment area. The findings of this study can provide valuable insights and information for state officials and decision makers in the field of public health.

Echolocation as a Means for People with Visual Impairment (PVI) to Acquire Spatial Knowledge of Virtual Space

In virtual environments, spatial information is communicated visually. This prevents people with visual impairment (PVI) from accessing such spaces. In this article, we investigate whether echolocation could be used as a tool to convey spatial information by answering the following research questions: What features of virtual space can be perceived by PVI through the use of echolocation? How does active echolocation support PVI in acquiring spatial knowledge of a virtual space? And what are PVI’s opinions regarding the use of echolocation to acquire landmark and survey knowledge of virtual space? To answer these questions, we conducted a two-part within-subjects experiment with 12 people who were blind or had a visual impairment and found that size and materials of rooms and 90-degree turns were detectable through echolocation, participants preferred using echoes derived from footsteps rather than from artificial sound pulses, and echolocation supported the acquisition of mental maps of a virtual space. Ultimately, we propose that appropriately designed echolocation in virtual environments improves understanding of spatial information and access to digital games for PVI.