We own in Fountains, and aside from one stay in Spas, have spent all of our SVR vacations in either the Fountains or Lakes sections. We walk from one side of the resort to the other all the time, and its very pedestrian friendly. When you have to cross the road at the security gate, that point is basically the end of the traffic on the road. All vehicles entering at the lights at the end of the street have either turned into Walgreens or the gas station, turned into Vista Way (the community for Disney cast members, adjacent to SVR property), or are turning left or right at the gate to enter the resort property. The road does continue onward, but that area appears to be a service type area (for the resort, or ???) so we hardly ever see a vehicle go past the gate and drive straight on through.
As you are walking out, stay on the sidewalk to the right of the gate, and you'll be able to cross without so much as a wait. There is a split sidewalk on the other side (marked one path for foot traffic, the other for golf carts) so walking is super safe. Distance, of course, is a whole other beast!! And distance becomes very subjective between different seasons....what's a nice, pleasant walk in mid-February can be brutal in mid-August.
If we want breakfast from the marketplace (which we enjoy regularly.....the Starbucks coffee there is pretty good) we generally drive over. Walk for pleasure, drive for food. But....my husband is a big eater and a long walk when he's hungry makes him crabby

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