The AirTrain at Newark-Liberty International Airport will halt operations on May 1 for 75 days while maintenance is underway (HT to EWR764 on FlyerTalk). Comments on FlyerTalk are not kind, though it seems the net conclusion is an already despised transit system is merely going from bad to worse.
AirTrain is not only a major means of transit between terminals but also a link between the airport and the nearby train station that runs along the airport property, with commuter trains heading east to New York and west to Philadelphia. United even markets “flights” to ZFV, the Philadelphia 30th Street Station, that involve flying to Newark and getting a connecting train to the city — more convenient in many cases than flying to Philadelphia’s airport.
The train station will shut down and existing rail service will not stop at the airport. Instead there will be shuttle services to Newark Penn Station. No news yet on what United will do about customers already booked to ZFV, though I imagine you’ll just have to take a shuttle bus to Penn Station to make your connection.