TARGET 060621

Moving a lighthouse

Cape Hatteras Light was 1600 feet (490 meters) from the ocean when it was completed in 1870. In June 1999 it stood just a few feet from the open beach, protected by rows of sandbags but vulnerable to the next passing summer hurricane or winter nor'easter.

Everyone agreed that if nothing was done the sea would destroy the lighthouse before our eyes within a very few years. The National Park Service, which owns most of Hatteras Island as part of the Cape Hatteras National Seashore, decided to move the lighthouse and its associated buildings 2900 feet (about 880 meters) to the southwest. This move, diagonally away from the ocean, places the lighthouse about as far from the sea as it was in 1870.

There was substantial opposition to the move, much of it coming from residents of Hatteras Island and of the Outer Banks. Opponents of the move were afraid the lighthouse was too large and too old to move; they feared it would crumble en route and be lost. They believed the lighthouse was historic where it stood, and some of that historical context would be lost in a new location. And they believed that the beach in front of the lighthouse could be preserved by building a new groin (a wall projecting into the ocean, designed to trap sand moving along the coast) and by installing other sand-catching devices in the surf.

In 1988, the National Research Council, an arm of the National Academy of Sciences, released a report, requested by the Park Service, which considered all the available options and recommended strongly that the lighthouse be moved.

In 1997, Governor Hunt and other state leaders asked the NC State engineering and science faculties to review the NAS-NRC report and update it if needed. The faculty concluded the original report was correct and the lighthouse should be moved.

There's no doubt lighthouses can be moved. Three have been moved in recent years in New England: the Cape Cod Highland and Nauset lighthouses in Massachusetts and the Southeast Block Island lighthouse in Rhode Island. However, opponents of moving Cape Hatteras Light were correct in pointing out that North Carolina's lighthouse is a different animal from these New England structures.

New England lighthouses are typically built on top of cliffs overlooking the ocean, not on sandy beaches. These lighthouses don't need to be tall, since they are already up in the air. The three relocated lighthouses are from 48 to 62 feet tall (14.6-18.9 meters) and weigh around 500 tons (450 metric tons) each. Cape Hatteras is the nation's tallest and (probably) heaviest lighthouse; it is the tallest brick lighthouse in the world. At 208 feet tall (63.4 meters) it is four times the height and ten times the weight of its New England cousins.

The foundation of the building was excavated and a diamond-studded saw was used to cut through its granite foundation. As the granite was removed, steel pillars, called shoring towers, were substituted to support the structure. Hydraulic jacks were used to lift the building slowly from its old location.

The lighthouse was then eased very slowly towards its new location, pushed by five large hydraulic rams mounted on the rails behind the base. The rate of motion was about 25-100 feet or 8-30 meters per day: so slow the lighthouse did not appear to be moving at all. It took more than a month for the lighthouse to reach its new home.

Because it has a heavy base and tapered shape, the lighthouse is not at all top heavy. This means it did not have any tendency to tip over. Although there was a lot of concern about the lighthouse cracking when it was moved, engineers said the building is so massive in construction it was actually a very good candidate for being moved without any damage of this kind. The real problem was to be sure that the ground underneath was firm enough over the whole route to permit a smooth passage. For this purpose the soft surface sand was removed along the route and replaced with a thick bed of gravel.

The two lightkeeper's houses and other associated structures around the base of the lighthouse were also moved. They weren relocated so they will have exactly the same relationship to the lighthouse they have had since they were built. (However, in one important respect the new location will not be authentic: it is surrounded by dense shrubbery at the edge of the Buxton Woods maritime forest. Old photos show that since 1870 the lighthouse has always stood in a relatively open, sandy site.)

As famous as the lighthouse already was, the move made it much more famous. It is amazing to think of moving such a structure, but perhaps not more amazing than to think of building it, on a sandy beach in one of the most exposed places in the world, in 1870. No doubt the builders of the lighthouse would be proud to see the level of concern and talent being concentrated on its preservation.

Many thanks to Ken Dye for this target.