Where you have the To and From locations at the top of the screen with the arrow separating the two, you might give the ability for a user to tap on that arrow or an icon that would reverse those driving directions.

Where this would be helpful: in my case, I have two kids that play sports and often get rides with other parents to and from San Diego to orange county. This drive time fluctuates so much based on traffic that this would be helpful to know when I can expect my kids to get home. They don’t always call. Thank you, Charlie