Substantial repairs begin at New York’s Pennsylvania Station on Monday, which involves a number of track closures and schedule changes. The plan will disrupt rail services for thousands of commuters taking Amtrak, Long Island Rail Road and New Jersey Transit until the beginning of September.

10TH AVE. NINTH AVE. EIGHTH AVE. SEVENTH AVE. W. 33RD ST. Track 20 Usage during peak periods 18 Track 13-21 Long Island Rail Road 16 L.I.R.R. West Side Yard 14 Hudson River tunnel 12 Repair area April 3 derailment 10 East River tunnels Empire Connection Track 5-12 Shared by Amtrak and New Jersey Transit 8 March 24 derailment 6 4 Track 1-4 New Jersey Transit 2 W. 31ST ST. 10TH AVE. NINTH AVE. EIGHTH AVE. SEVENTH AVE. W. 33RD ST. Track 20 Usage during peak periods 18 Track 13-21 Long Island Rail Road 16 L.I.R.R. West Side Yard 14 Hudson River tunnel 12 Repair area April 3 derailment 10 East River tunnels Empire Connection 8 Track 5-12 Shared by Amtrak and New Jersey Transit March 24 derailment 6 4 Track 1-4 New Jersey Transit 2 W. 31ST ST. 10TH AVE. NINTH AVE. EIGHTH AVE. SEVENTH AVE. W. 33RD ST. Track 20 18 14 Repair area April 3 derailment 10 March 24 derailment 6 2 W. 31ST ST. 10TH AVE. EIGHTH AVE. W. 33RD ST. Track 20 18 14 Repair area April 3 derailment 10 March 24 derailment 6 2 W. 31ST ST. Source: Amtrak | Note: Diagram is schematic and not to scale.

After two derailments that caused major disruptions this year, Amtrak determined that track conditions have reached a critical point. Another derailment occurred on Thursday, a few days before the beginning of construction.

The derailments happened in a junction called the “A Interlocking,” a complex of switches west of the passenger platforms where 21 tracks converge to connect the station to Hudson River tunnels, Long Island Rail Road’s West Side Yard and the Empire connection to points north.

Amtrak has long known the interlocking was in need of renovation. In a New Jersey Legislature hearing, Scot Naparstek, Amtrak’s chief operating officer, highlighted the vulnerability of this interlocking system.