Charlotte Douglas International Airport is an international airport in Charlotte, N.C., and as of 2019, it was
processing more than 50 million passengers. When it was determined that additional runways were needed
at the airport, the City of Charlotte and the city's aviation department turned to reroute a creek to provide
additional space. The Coffey Creek Tunnel is an ambitious project that will reroute an existing creek and then backfill the area for new taxiways. To do this, Doka provided four sets of foundation formwork so concrete contractor Briegan Concrete could always be actively pouring foundations. Doka also provided two sets of tunnel formwork – equaling four 70-foot-long tunnel forms – so Briegan could work in two different areas of the project. To help the customer understand the process, Doka built a mockup of the tunnel section so it could be seen in full scale. This was an advantage since it showed the customer how Doka could help them visualize the process and have a successful project.
The first challenge encountered was designing the foundation formwork so it could be moved using the limited amount of equipment available. In particular, the jobsite did not have access to a large crane. Then, Doka bias cut corners had to be modified to form the 4-inch chamfer in the top corners of the interior of the tunnels. These corners are used to help strip the interior forms. It was also important to design the formwork solution with minimum weight so the customer could move the complete, interior 70-foot-long tunnel section with the walls and roof attached.
Frami was the ideal solution to form the tunnel sections due to its lightweight design. Part of the solution was to connect the panels with Frami clips instead of Frami clamps to cut down on the weight of the tunnel form. Frami was favored because the panels are lightweight and easy to handle, so they can be erected very quickly by hand, without the use of a crane. The ingenious modular design makes for optimum adaptability to all jobsite conditions. All of this was possible because Doka was able to provide unmatched service, from customer management to engineering. To assist the customer in the correct alignment of the tunnel roof, all of the roof sections were assembled in Doka‘s yard. Additionally, by providing the modified bias-cut corners and the Winch 125 with wheels and a Trolley TT, it helped the customer move the 70-foot-long tunnel sections with relative ease.