Best Practices for Mission Applications

Predicting Drive Time from Haversine Distance to Care Sites

—Christopher Richmond, Veteran Affairs

When studying access from residential locations to healthcare service facilities there is near universal agreement that travel impedance across a transportation network is a better measure of access than either straight line or vincenty (great circle) distance. Nevertheless there are instances when only straight line or haversine measures are available. A major facet of VHA planning involves the statistical analysis of estimated drive time from each enrollee residential location to the nearest facility. On an annual basis we geocode these enrollees and estimate drive distance to nearest facility using ArcGIS Network Analyst and ESRI StreetMap Premium. To address the needs of local planners we have explored the relationship between drive time on the one hand and haversine distances on the other. Our goal is to develop regression models that can be used to accurately estimate drive time from vincenty distance.