Thursday, October 8, 2009

What is a pigtail bridge – and why do Sturgis rally goers ride them?

No, they are not some contraption that connects one hawg to another. But hawg riders have used them for about as long as there has been a Sturgis Motorcycle rally. They are wooden bridges that wind under or over themselves to give traffic a gentle slope on the steep inclines of the Black Hills. You’ll find several on highway 16a directly south of Mount Rushmore and the town of Keystone.

Pigtail bridges are one of the attractions on Iron Mountain Road, a favorite ride of bikers. Its twists, turns, tunnels and pigtail bridges are unequaled anywhere in the U.S. A few years ago, I rode the Black Hills with a group of bikers I met on a large bridge project in North Dakota. We rode down to the Hills, and to Iron Mountain Road. They had to stop to inspect these engineering wonders.

The rustic log work is impressive. When riders take a moment to pull over and read nearby signs, they will learn the logs were cut from stands nearby, shaped, treated and put in place about 80 years ago. The piling, the piers, the pier caps, the deck supports and the deck railing are all treated wood cut from just a few yards away.

They were designed and engineered in 1932 by Cecil Clyde Gideon who was the superintendent of Custer State Park. (That’s the park at the south end of Iron Mountain road where bison and other wildlife thrive. You’ll see photos here of Custer and the bison in my blog archive and on

Gideon called the bridges “spiral-jump offs”. His goal in designing the bridges was to preserve the natural beauty while building a scenic highway on Iron Mountain. The corkscrew design is eye-catching, and every rider ought to stop at least once to check them out. I mean, after all, they have to slow down anyway to traverse the tight turns. I recommend checking out this impressive design that blends engineering into modern traffic – a kind of early contest sensitive design.

If you get the chance to ride Iron Mountain Road and experience the corkscrew twist of a pigtail bridge – stop! Get off the road a bit, get off your bike, and look at how they are put together. And if you’re really brave and physically fit, take a climb up the nearby rocks to see how the road and bridge wraps around – a simple fix to a complex problem.

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