Railroad in Burlington, MA

The Bedford part of that right-of-way is a semi-paved (stone-dust) walking and bicycling trail. Once you cross into Billerica it turns into sand and dirt, then disappears entirely for a while into an office park. On the other side of Route 3, the right-of-way picks up again, but isn't really walkable due to dense vegetation. I think some of it is now a power-line right of way.