New Jersey Transit and Amtrak are nearing the end of the first week of the project to replace the 100-year-old Portal Bridge. This first phase of work will last a total of four weeks.

NJ Transit allowed News 12 to take a close-up look at the work being done on the bridge, which sits across the Hackensack River in Kearny.

Railroad tracks, signals and catenary wires are installed on the new bridge. The work is continuing around the clock to properly and safely connect all of those mechanisms to the existing Northeast Corridor Line to make it fully functional.

“Those wires are in place, but now we’re doing the fine-tuning and tweaks to get them ready to actually run the trains," said Jason Hoover, with Amtrak.

Transit authorities say they’re on schedule.

On March 15, the plan is to have one track running out of New York City on the new bridge and one using the current bridge in the opposite direction. This first phase will take four weeks to complete.

After 100 years of use, the current Portal Bridge has to be replaced. The new version is 50 feet taller, so it won’t need to swing open for ships and boats, ensuring fewer delays for rail commuters passing over the river as they go into and out of New York City.

The current bridge will be torn down in 2027.