Dismal Swamp: A Retrospective

The Dismal Swamp Canal is part of the Atlantic Intracoastal Waterway, a route of interconnected rivers and lakes that stretches between the Gulf of Mexico and Massachusetts. As both an alternate travel route and a historic landmark, the Dismal Swamp welcomes nearly 2,000 boaters annually as they pass through the largest remaining swamp in the eastern United States.

The waterway also crosses under a small road that carries cars into the Dismal Swamp State Park. Since cars and boats require access to the same location, this created a conflict between both sources of traffic. Seeing the problem, the NC Division of Parks and Recreation requested that Alpha and Omega Group design a compromise: a bridge that supports traffic and also moves when needed for boats to pass through. This challenge has been one of our longest lasting and most interesting projects to date.

The Dismal Swamp Bridge in motion

A&O was chosen to provide structural and civil engineering to design the bridge leading into the park as well as the park’s Visitor Center. The bridge offered a unique dilemma since it needed to hold the weight of the roadway vehicles and allow traffic from the canal to pass through. The answer? A floating swing span bridge that would allow both land and canal traffic to pass. We designed the bridge in three parts, with a three-span fixed section for canoes to pass without opening the canal and a bascule ramp that lifts up on each end of the center segment. This allows the middle floating barge segment to swing to the side, so that canal traffic is able to pass through. That middle segment floats on the canal, allowing cars to pass and eliminating any issues with rising flood waters.

The Completed Visitor’s Center

Rising river water was just one part of the challenges in designing the Visitor’s Center. Since the Dismal Swamp is so close to the coast, and both hurricanes and flooding are possible, and the Visitor’s Center needed to be built on high ground. The solution was one that allowed history and the present to blend. During the canal’s original construction, workers deposited the soil that they excavated on only one side of the canal. This large, raised section of the canal actually created a raised base for the Visitor Center that could help protect the new building from flooding and erosion while allowing it to have a close proximity to the bridge. Today, the Visitor’s Center is the only rest stop on the Intracoastal Waterway that also serves the highway, allowing travelers to learn about the swamp, the canal, and its historical significance at their leisure in a place that connects to that history.

But these accomplishments did not end A&O’s connection to the Dismal Swamp and its bridge. The Dismal Swamp exists in a coastal environment, and so the structures built along the canal are subject to erosion from the canal wave action caused by boats, but also to the constant wear of the weather and coastal air. Due to this exposure, repairs and maintenance are necessary much sooner than for other regions of the state.

The Refurbished bridge

In 2021, the NC Division of Parks and Recreation contacted us again with the need to inspect and upgrade the gate houses and make repairs to the bridge. The coastal environment and constant use had caused the bridge and gatehouses to start showing signs of wear. To refurbish and preserve the bridge, we oversaw the disconnection and transport of the bridge for repairs. After being disconnected, it was transported to Chesapeake using the waterway. There it was set ashore, disassembled, cleaned, repainted, and repaired before being returned and reconnected. By doing this, we extended the life of the bridge, making a full replacement unnecessary and keeping the bridge looking fresh and new.

The Dismal Swamp bridge and Visitors Center play a vital role to visitors. It acts as a center for exhibits and events as well as a place for travelers using the intracoastal waterway to rest. The park itself and surrounding area could be called the last wild place in North Carolina and Virginia, offering a slice of both state’s rich and complex history preserved for future generations.

As we look back on our 25-year history, Alpha & Omega Group is proud to contribute to the legacy of the Great Dismal Swamp and its ability to continue to educate the many visitors to one of our state’s greatest natural wonders.