@joela85 so the google API doesn’t allow that specifically, but there are a couple of ways we could accomplish something similar:
I can have Google return alternative routes, and they can be listed out. No garantee you’re going to get any of the routes you’re interested, but they will be the fastest.
you can provide a list of waypoints and Google will return your route passing through those specific places. So if you put specific landmark addresses that are on the highways you’re interested in then you would more or less get the result you’re looking for.
Both of these options seem fairly straightforward to add so I might just do both