Ever Wonder Why the New River Gorge Bridge Looks Rusty?

Most people who casually glance at the New River Gorge Bridge aren't thinking about what it is made of.  But to a highways engineer, or maintenance supervisor, or architect, this would be the first thing they'd think of. Why?  Because the New River Gorge Bridge is a beast when it comes to maintenance, upkeep and inspections. Imagine trying to paint or work on a bridge that is almost 900 feet off the ground.

Fortunately, that challenge was foreseen by design engineers before the bridge was built.  The solution?  COR-TEN steel.

COR-TEN

COR-TEN steel is a trademark registered product of United States Steel Corporation. It was developed in the 1930's, mostly to use in railroad coal cars. It is a special blend of steel alloys that, when exposed to weather, develop a thin, protective rust layer that coats and protects the metal. Some of its early use in civil engineering projects in the 1960's gave way to architectural uses not long after.

It was an ideal choice for the New River Gorge Bridge because it solved a couple of problems. The expense of painting such a large structure would have been cost-prohibitive. Using COR-TEN not only saved $300,000 in construction costs, but also an estimated $1,000,000 every time the Bridge would have had to been painted.

Also, when COR-TEN weathers, it turns a dark rust color.  This means it blends in with its outdoor environment. This is even more evident in the late fall when the Bridge almost disappears into its surroundings.

Challenges

The use of COR-TEN on the NRG Bridge was not completely ideal. One of the issues that must alway be addressed with COR-TEN is to make sure the welds weather at the same rate as the rest of the steel.

Another issue, discovered after the Bridge was built, was the challenge of using road salt in the winter to keep ice off the Bridge. It was accelerating the rusting process and deteriorating the metal. An alternative had to be eventually be developed and used.

So the next time you look at the New River Gorge Bridge, you'll know why it looks rusty.  There's a reason!