A new round of construction begins Monday at Penn Station, and that could mean big changes for Long Island Rail Road commuters.

The next phase of Amtrak's Renewal project means the LIRR will operate with one less track at the Manhattan transit hub for the next two months.

As a result, seven morning rush trains  and six evening rush trains will be re-routed or canceled.

Gerry Bringmann is the vice chair of the LIRR Commuter Council. He says Long Island commuters traveling before or after rush hour will barely feel the impact. But he says rush-hour commuters will have some adjustments.

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"If you are in the middle of the rush hour, there will be some canceled or combined trains, there will be some trains that will be terminating in Jamaica, there will be other trains rerouted from Penn Station to Flatbush Avenue, so those people will be affected and will have to make some adjustments,” he says.

To help with overcrowding, the LIRR is adding two morning trains and three evening trains, as well as extra cars to increase seating capacity.

LIRR President Phil Eng says, "Amtrak's Penn Station renewal work is critical to the LIRR's continued operation to Manhattan's West Side and needs to be done as quickly as possible."

Railroad officials say commuters will be updated on travel options and the latest service updates through their email and text alert system, on social media and recorded platform announcements.