The Pope plays Madison Square Garden on Friday.

That's good news for those planning on attending the special evening Mass at the Garden, but bad news for those catching a train downstairs at Penn Station.

The Metropolitan Transportation Authority and Long Island Rail Road said access to and from Penn Station will be restricted Friday -- and that it will be "most-restricted" between 5 p.m. and 8:30 p.m., during the Papal Mass.

Commuters are being warned about a slew of prohibited items in the station on Friday, among them aerosols; ammunition; animals other than service or guide dogs; backpacks exceeding pre-set size restrictions; balloons; bicycles; and a host of other items, including glass, thermal or metal containers, lasers and even selfie sticks.

The MTA said customers taking the New York City subway, Metro-North Railroad and the LIRR for papal events should buy round-trip MetroCards or tickets in advance -- and expect crowding.

"Pope Francis' visit to New York is a significant honor for everyone in our service area, and we are prepared to accommodate additional customers traveling to his events along with our 8.6 million average weekday customers," MTA Chairman Thomas F. Prendergast said in a statement. "While some schedules and routes may change, we are ready to get everyone where they need to go during this special time."

The MTA will run extra service on the LIRR on Friday.

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Several bus routes will be diverted from streets near the Garden from late morning through late evening Friday to avoid the Papal Mass.

Subway operations will also be adjusted, as necessary.

The LIRR said it will operate eight extra westbound trains into Penn Station, including three on the Babylon Branch leaving Babylon at 12:20 p.m., 12:43 p.m. and 1:20 p.m.; two on the Port Jefferson Branch leaving Huntington at 12:19 p.m. and 1:19 p.m.; one on the Port Jefferson Branch leaving Hicksville at 1:07 p.m.; and two on the Ronkonkoma Branch leaving Ronkonkoma at 12:40 p.m. and 1:40 p.m.

Penn Station will remain open during the Papal Mass, but some individual staircases may be closed at times for security reasons or to manage crowd conditions.

Extra eastbound trains will be on standby at Penn Station to carry people back to Long Island at the conclusion of the Mass.

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For a complete listing of all pope-related changes, regulations and restrictions, officials are asking riders to check the MTA website at www.mymtaalerts.com.