Tunnels Along the Parkway. Tunnels are an iconic feature of the parkway. In fact, 36% of all road tunnels found in national parks across the United States are found here on the parkway. There are 25 tunnels in North Carolina and one in Virginia. These tunnels are listed below by milepost, length, maximum height (over the center of the road), and minimum height (over the edge of the road). If you are driving a large motor home, be certain that your vehicle will have enough clearance to travel through the tunnel safely.