Hello all,

I am trying to find a Census Block Group level data set that contains not only the number of  public transit stops in a given census block group but also how many other census block groups can be reached from a given location. I have considered running a scraping algorithm that will measure the transit time via Google Maps from the population centroid of each census block group to all others within a 45 minute time frame. That is, I will have the time and ID of each census block that can be reached within a 45 minute public transit commute from a given starting location. This, however, seems extremely time-consuming and potentially not the most effective way to do this. Does anyone know of a dataset that contains the "connectivity" of a census block via public transit? I apologize if this isn't the right sub for this, I'm just running out of places to look. Thank you for your time.