Blue Ridge Parkway tunnels

"Blue Ridge Parkway tunnels" consist of a total of 26 vehicle tunnels constructed along the convert|469|mi|km of the Blue Ridge Parkway. One, the Bluff Mountain Tunnel, [ [http://www.drivingtoday.com/ftp/2007-11-05/legendary_virginia2.html Blue Ridge Parkway North] ] is in Virginia and twenty-five are in North Carolina. [ [http://www.virtualblueridge.com/parkway/general/tunnels.asp Virtual Blue Ridge tunnels] ]

The design standards specified a minimum impact on the land. The vehicle tunnels were often constructed to reduce excessive landscape scarring that open cuts would have produced. They are used in areas of steep terrain where ridges run perpendicular to the roadway alignment.

North Carolina's more rugged terrain required the majority of the tunnels. Most of the work on the tunnel digging was done by hand and provided by the Civilian Conservation Corps in the 1930s. [ [http://ncnatural.com/Parkway/BRP-History.html Blue Ridge Parkway history] ] Little machinery was used with the intention of creating manual labor in depressed economic times. They did have for tunneling truck-mounted water-cooled compressed air drills called "Jumbos." After the initial holes were drilled into the substrata, dynamite was used for blasting away the rock. [ [http://www.nps.gov/history/history/online_books/hih/blue_ridge/blue_ridge8.htm Blue Ridge Parkway tunnels] ] Concrete lining was done during construction due to tunnel cave-ins. [ [http://sections.asce.org/n_carolina/CE%20Trails/web_pages/BRPTunnels.htm Blue Ridge Parkway Tunnels] ] This concrete lining was first used in the Devil's Courthouse Tunnel. It was later discovered that it enhanced the interior lighting within the tunnel itself. Where done the lining covered about a quarter of the interior structure. An additional benefit was the elimination of moisture entering the tunnel. Moisture in the winter caused ice problems. ["Historic American Engineering Record," National Park Service, Jennifer K. Cuthbertson, 1997 (Sheet 1 of 28) and Lia M. Dikigoropoulou, 1997, (Sheet 24 of 28).]

The Pine Mountain Tunnel is the longest on the Parkway at convert|1434|ft|m. Ferrin Knob Tunnel #1 is the first and longest of the "triplet tunnels." The triplet tunnels are named because of the profusion of ferns growing on their backs. The local people once referred to ferns as "ferrins." Ferrin Knob Tunnel #2 is located at milepost 401.3 and Ferrin Knob Tunnel #3 is located at milepost 401.5.

The distinctive stone masonry portals now on the parkway tunnels were generally not part of the original construction of the 1930s. They were added later. [ [http://www.nps.gov/history/history/online_books/hih/blue_ridge/blue_ridge8.htm PartNet - National Park Service] ]

The tunnels are listed below by milepost, name, and length. [ [http://www.blueridgeparkway.org/blue_ridge_parkway_tunnels.htm The Blue Ridge Parkway Association] ] The maximum height is in the center of the tunnel [ [http://www.nps.gov/blri/planyourvisit/tunnel-heights.htm National Park Service tunnel heights] ] and the minimum height is at the edge stripe. [ [http://www.nps.gov/archive/blri/tunnels.htm The tunnels along Blue Ridge Parkway] ]

References

Location

* [http://maps.google.com/maps?ll=35.853475,-82.096963&z=9&t=h&hl=en Google maps location of Bluff Mountain Tunnel]
* [http://maps.google.com/maps?ll=35.853475,-82.096963&z=9&t=h&hl=en Google maps location of Little Switzerland Tunnel]
* [http://maps.google.com/maps?ll=35.853475,-82.096963&z=9&t=h&hl=en Google maps location of the 3 Ferrin Knob Tunnels]
* [http://maps.google.com/maps?ll=35.853475,-82.096963&z=9&t=h&hl=en Google maps location of Rattlesnake Mountain Tunnel]