This generalized version of the Canadian Accessibility and Remoteness Index (CARI+) measures rurality using a population-weighted score to population centres by travel time and distance.
Citation:
McGaughey T & PA Peters. (In Press) Introducing the Canadian Accessibility and Remoteness Index (CARI+). Canadian Geographies / Géographies canadiennes.The CARI+ is a flexible, small-area methodology that quantifies accessibility based on road-network travel time and distance to population centres and service-specific locations. The CARI+ builds on international best practices such as the Accessibility and Remoteness Index of Australia (ARIA+), while adapting their principles to the Canadian context. It provides both continuous and categorized scores, enabling nuanced analysis across the rural-urban continuum. Crucially, the CARI+ is calculated at the level of Dissemination Areas (DAs), which are smaller geographic units typically containing 400–700 individuals, and are the smallest census geography for many publicly available socio-demographic tabulations.
Calculation of CARI+ Scores
CARI+ scores for travel distance and time are provided from population-weighted DA centroids to service centre locations. These are determined using population-weighted Dissemination Block (DB) centroids and population counts. Population (service) centres were defined using community community-level CSD (census subdivision) boundary files grouped into six size categories based on the population cutoffs from the Statistics Canada 2021 Statistical Area Classification (SAC).
Travel distance and time from each population-weighted DA centroid to the closest service centre were calculated for each population-size category, producing six travel-time and six travel-distance measures. The calculated scores within each category indicate relative accessibility and were capped at 3. The overall score for a DA was within a range of 0-18 and is the result of summing the scores for all six categories, followed by normalizing to be scaled to 0-1, with 0 as the easiest access and 1 as the hardest.
The final normalized CARI+ index ranges from 0 to 1, where 0 represents the highest level of accessibility. This normalization procedure was applied separately to both travel-time and travel-distance measures.
Classification of CARI Scores
The resulting continuous CARI+ scores were classified into five categories (easily accessible, accessible, less accessible, remote, very remote) to facilitate comparison with other measures of rurality. We evaluated several standard classification schemes — manual classification, equal intervals, quantiles, Jenks natural breaks, and standard deviation — to illustrate how different approaches partition the continuous index. These can be visualized on our interactive map and socio-demographic gradients can be viewed via our interactive Census Summary tables.
Data Analysis
Spatial boundary and road network files for 2021 were uploaded to ArcGIS Pro, and the DA centroids were merged with 2021 population counts. The Canadian Road Network File was processed in ArcGIS and generated through Network Analysis. The locations of different services were added to ArcGIS Pro. Using them and the centroids, the travel time and distance was generated. After being exported as CSV files, the information and results obtained were processed through Python version 3.10 to produce population weighted travel times and distances for each CSD.