Carpool Bot
This would be an OPT-IN only feature. Create a script that recognizes where each member is coming from without disclosing their precise location. Based on starting locations and where the activity starts i.e. trail head, let participants know based on that data how much of their likely drive routes match up. For example: You would get a notification that you and another participant are likely to share 90% of the same roads to travel to the activity. The user could set the tolerance of how much of the route to share. 70, 80, 90% etc. in order to get a notification. I hear a people often say they wish they knew how close another participant was prior to as they would have carpooled.