The third and final arch has been installed to Portal North Bridge, a major part of the Northeast Corridor.

"The most intense busiest main line railroad in all of North America is right here," said Stephen Gardner, Amtrak CEO.

The 2.5-mile bridge will replace the current 114-year-old swing bridge, which opens for maritime traffic and often has mechanical issues that result in train delays.

Gardner and NJ TRANSIT President and CEO Kris Kolluri said this is an important element of the broader Gateway Program that will eventually double rail capacity between Newark and New York.

"This is the foundation of our economy," said Kolluri. "This is not just about moving people through the corridor daily in a safe and reliable manner, but it is about making sure that we have an infrastructure worthy of the 21st century."

They hope to have one track on the bridge operational by fall of next year. The second and final track will follow after that.