A massive two-month repair project launches Monday at the busiest train station in the United States, and commuters used to regular delays and service disruptions are bracing for the worst.

Two minor derailments and other problems at New York's Penn Station this spring prompted Amtrak to accelerate repairs it had initially planned to perform over a few years. Last Thursday, there was another minor derailment at the station.

To accommodate the replacing of tracks and signals, commuter rail service is being reduced by about 20 percent, and Amtrak will run fewer trains between New York and Washington, D.C.

NJ Transit is urging all Morris and Essex Line customers to check for new schedules, train times and stops.

Midtown Direct trains on the Gladstone Branch will be diverted to and from Hoboken.

Midtown Direct trains on the Montclair-Boonton Line will operate with minor time changes to and from New York Penn Station, as well as the Northeast Corridor trains.

Hoboken-bound North Jersey Coast Line trains will end at Newark Penn Station.

The repairs will improve reliability, but they won't add capacity or ease overcrowding at Penn Station. That won't happen until a new tunnel is built under the Hudson River, a project that faces lingering questions over how much funding President Donald Trump's administration will provide.

For more details and updates over the course of the repairs, visit News 12’s Commuter Chaos section.