A GIS approach to the development of a segment-level derailment prediction model.

Train related accidents, particularly derailments, can lead to severe consequences especially when they involve injuries or fatalities or when they involve hazardous materials that might result in environmental impacts. Whereas numerous road safety studies have suggested appropriate approaches to predicting vehicle-to-vehicle collisions, very few railway safety studies have considered predicting the number of derailments on rail tracks in North America. In addition, the existing few rail safety assessment and derailment prediction models have often been constrained by aggregated data limiting the safety assessments by, for example, failing to consider segment-level characteristics. This paper focused on the development of an integrated database for the development of a segment-level derailment prediction model for Canada's rail network. The primary objective of this paper is to report how challenges in the data integration process were overcome and also to develop a network screening tool to identify segments with high derailment risk in Canada's rail network. Negative binomial regression and the Empirical Bayes technique were used to estimate the predicted number of derailments on Canada's rail network at the segment level. A network screening process was then successfully applied to identify key segments of safety concern: the top ten segments of concern accounted for approximately 1% of the rail network allowing decision makers to focus their derailment mitigation efforts on a manageable part of Canada's vast rail network. The data processing approach and analysis in this study have strong implications for advancing research on rail safety in North America.

Determining geographic accessibility of family physician and nurse practitioner services in relation to the distribution of seniors within two Canadian Prairie Provinces.

Equitable access and distribution of health care services for rural and remote populations is a substantial challenge for health workforce planners and policy makers. Geospatial examination of access to health care considers both need and supply dimensions together to determine spatial access scores which contribute to a greater understanding of potential inequity in accessibility. This geospatial investigation explores geographic variation in accessibility to primary health care services utilizing combined access scores for family physicians and nurse practitioner services in urban and rural communities in the Canadian Prairie provinces of Saskatchewan and Alberta. An index of access scores was developed using a floating catchment area framework and a census subdivision geographic unit. Information about family physician and nurse practitioner practice locations and spatial population data were obtained from the Canadian Institute for Health Information and Statistics Canada respectively. Alberta has a better overall provincial access score than Saskatchewan for family physicians and nurse practitioners combined (11.37 vs. 9.77). The results demonstrate that nurse practitioner services are likely addressing primary care access gaps due to reduced numbers of family physician services in certain geographical areas. Combined access scores reveal inequalities in the distribution of primary health care services relative to the proportion of population aged 65 + across both provinces, particularly in rural and remote communities. This study contributes to health services research by exploration of combined access scores for family physician and nurse practitioner services in relation to the distribution of seniors. These findings provide insight into which areas may be in need of increased primary health care services with a focus on both of these health professional groups. The findings of this research will serve as a foundational model for future expansion of the methods to other health care provider groups and to other population health need indicators provincially and nationally.

Measuring geographical accessibility to rural and remote health care services: Challenges and considerations.

This research is focused on methodological challenges and considerations associated with the estimation of the geographical aspects of access to healthcare with a focus on rural and remote areas. With the assumption that GIS-based accessibility measures for rural healthcare services will vary across geographic units of analysis and estimation techniques, which could influence the interpretation of spatial access to rural healthcare services. Estimations of geographical accessibility depend on variations of the following three parameters: 1) quality of input data; 2) accessibility method; and 3) geographical area. This research investigated the spatial distributions of physiotherapists (PTs) in comparison to family physicians (FPs) across Saskatchewan, Canada. The three-steps floating catchment areas (3SFCA) method was applied to calculate the accessibility scores for both PT and FP services at two different geographical units. A comparison of accessibility scores to simple healthcare provider-to-population ratios was also calculated. The results vary considerably depending on the accessibility methods used and the choice of geographical area unit for measuring geographical accessibility for both FP and PT services. These findings raise intriguing questions regarding the nature and extent of technical issues and methodological considerations that can affect GIS-based measures in health services research and planning. This study demonstrates how the selection of geographical areal units and different methods for measuring geographical accessibility could affect the distribution of healthcare resources in rural areas. These methodological issues have implications for determining where there is reduced access that will ultimately impact health human resource priorities and policies.

Spatial Accessibility to Health Care Services: Identifying under-Serviced Neighbourhoods in Canadian Urban Areas.

BACKGROUND: Urban environments can influence many aspects of health and well-being and access to health care is one of them. Access to primary health care (PHC) in urban settings is a pressing research and policy issue in Canada. Most research on access to healthcare is focused on national and provincial levels in Canada; there is a need to advance current understanding to local scales such as neighbourhoods. METHODS: This study examines spatial accessibility to family physicians using the Three-Step Floating Catchment Area (3SFCA) method to identify neighbourhoods with poor geographical access to PHC services and their spatial patterning across 14 Canadian urban settings. An index of spatial access to PHC services, representing an accessibility score (physicians-per-1000 population), was calculated for neighborhoods using a 3km road network distance. Information about primary health care providers (this definition does not include mobile services such as health buses or nurse practitioners or less distributed services such as emergency rooms) used in this research was gathered from publicly available and routinely updated sources (i.e. provincial colleges of physicians and surgeons). An integrated geocoding approach was used to establish PHC locations. RESULTS: The results found that the three methods, Simple Ratio, Neighbourhood Simple Ratio, and 3SFCA that produce City level access scores are positively correlated with each other. Comparative analyses were performed both within and across urban settings to examine disparities in distributions of PHC services. It is found that neighbourhoods with poor accessibility scores in the main urban settings across Canada have further disadvantages in relation to population high health care needs. CONCLUSIONS: The results of this study show substantial variations in geographical accessibility to PHC services both within and among urban areas. This research enhances our understanding of spatial accessibility to health care services at the neighbourhood level. In particular, the results show that the low access neighbourhoods tend to be clustered in the neighbourhoods at the urban periphery and immediately surrounding the downtown area.

Investigating impacts of positional error on potential health care accessibility.

Accessibility to health services at the local or community level is an effective approach to measuring health care delivery in various constituencies in Canada and the United States. GIS and spatial methods play an important role in measuring potential access to health services. The Three-Step Floating Catchment Area (3SFCA) method is a GIS based procedure developed to calculate potential (spatial) accessibility as a ratio of primary health care (PHC) providers to the surrounding population in urban settings. This method uses PHC provider locations in textual/address format supplied by local, regional, or national health authorities. An automated geocoding procedure is normally used to convert such addresses to a pair of geographic coordinates. The accuracy of geocoding depends on the type of reference data and the amount of value-added effort applied. This research investigates the success and accuracy of six geocoding methods as well as how geocoding error affects the 3SFCA method. ArcGIS software is used for geocoding and spatial accessibility estimation. Results will focus on two implications of geocoding: (1) the success and accuracy of different automated and value-added geocoding; and (2) the implications of these geocoding methods for GIS-based methods that generalise results based on location data.

Neighbourhoods and potential access to health care: the role of spatial and aspatial factors.

The availability of, and access to, primary health care is one neighbourhood characteristic that has the potential to impact health thus representing an important area of focus for neighbourhood-health research. This research examines neighbourhood access to primary health care in the city of Mississauga, Ontario, Canada. A modification of the Two Step Floating Catchment Area method is used to measure multiple spatial and aspatial (social) dimensions of potential access to primary health care in natural neighbourhoods of Mississauga. The analysis reveals that neighbourhood-level potential access to primary care is dependant on spatial and aspatial dimensions of access selected for examination. The results also show that potential accessibility is reduced for linguistic minorities as well as for recent immigrant populations who appear, on the surface, to have better access to walk-in clinics than dedicated physicians. The research results reinforce the importance of focusing on intra-urban variations in access to care and demonstrate the utility of a new approach for studying neighbourhood impacts that better represents spatial variations in health care access and demand.