Story

The Tulip City Airport project involved the relocation of Washington Avenue in Holland, Michigan to provide for an airport runway expansion.  To accomplish this task, the Michigan Department of Transportation redesigned Washington as a four-lane divided highway, winding underground through a cast-in-place concrete tunnel.

The project schedule was very tight with a large part of the structural concrete work taking place in the winter of 2004 while adhering to stringent MDOT winter concrete specifications. Kent Companies' portion of this project began in late November 2003, with the last roof pour completed on July 13, 2004.  The road opened to traffic by November 2004.

On this project Kent Companies placed 21,559 cubic yards of concrete and over 3 million pounds of resteel in the 885' tunnel structure. The walls were 2'6" to 3' wide, 20' tall and had to be poured in 20' pieces while allowing 72 hours of cure time between adjacent pours.  This resulted in 132 separate wall pours during the harsh Michigan winter.  The resteel for the walls was tied on the ground at an average of 15 to 20 tons per day.

The roof was built using a unique shoring system, designed so construction trades and equipment could drive under the shoring while the roof was constructed. This was very important to the construction sequencing, as it allowed other trades access to the tunnel before the structure was completed. The system also allowed the forms to be lowered and move down the tunnel on tracks as a unit. There were 44 sections of roof poured in 20' wide x 80' long sections, each with 240 cubic yards and 64,000 pounds of resteel. The thickness of the roof varied from 3' to 4', with a 4' thick edge formed 20' in the air on brackets. As the roof was being placed, 8" road paving and curbs were poured inside the tunnel, as areas became available. The concrete road paving was complete within 2 weeks of the last roof pour.  

This project had many unique challenges such as:

• Hoisting 3 million pounds of steel with a crane at the end of an operational runway with height restrictions.
• Coordinate huge excavation machinery, concrete trucks and other trades in a long, deep and narrow excavation.
• Placing nearly 22,000 cys of concrete in over 180 different pours with 3 days cure between any adjacent pours, all in 6 months.