About 5,000 riders on Long Island Railroad will see their evening rush hour train either cut or delayed for as long as a month starting Monday.

The MTA is taking a single switch in Queens out of service so it can dig the next length of the East Side Access Tunnel — a project designed to bring LIRR trains to Grand Central Terminal.

Switch 813 regulates 1/3 of all eastbound train traffic as it passes through a massive switching yard called The Harold Interlocking.

The switch can't be operated while a giant boring machine is tunneling beneath it. With only two tracks remaining to handle the evening rush, train traffic must be juggled.

The MTA said riders can expect the following changes:

• The 4:52 PM train from Penn Station to Babylon will be canceled.
• The 5:20 PM train from Penn Station to Long Beach will be canceled.
• The 5:40 PM train from Penn Station to Seaford will be canceled.

The four PM Peak trains with adjusted schedules include:

• The 5:36 PM train from Penn Station to Babylon, which will depart Penn Station one minute later (at 5:37 PM) and arrive Babylon two minutes later at 6:42 PM.
• The 5:55 PM train from Penn Station to Long Beach will arrive at Long Beach one minute later at 6:52 PM.
• The 5:59 PM train from Penn Station to Babylon will arrive at Babylon five minutes later at 7:04 PM.
• The 6:44 PM train from Babylon to Patchogue will operate two minutes later, departing Babylon at 6:46 PM and arriving Patchogue at 7:16 PM as a result of its connecting train from Penn Station (the 5:37 PM) arriving two minutes later at Babylon.

The MTA has been alerting riders to the changes through an alert on its website, fliers posted at stations and dropped on trains seats, and email alerts to the 30,000 customers who subscribe to them.

Those efforts weren't enough for the Long Island Riders Council, which urged the LIRR to post workers in stations and on platforms during the first days of the schedule changes.

LIRR spokesman Sal Arena riders can expect to see LIRR workers in reflective vests at Penn and Jamaica Stations, and Atlantic Terminal. 

For more on East Side Access, go here.