Accessibility to Cities layerSource:
This resource is published by Weiss et al. (2018) "A global map of travel time to cities to assess inequalities in accessibility in 2015" on journal nature. Accessibility is the ease with which larger cities can be reached from a certain location. This resource represents the travel time to major cities in the year 2015. Encoded as minutes, representing the time needed to reach that particular cell from nearby city of target population range. The following ranges to nearby cities are available:
The following argument should be specified by users:
A character vector indicating one or more ranges to download.