Brace yourselves, commuters: There are big changes coming to the E and M trains at the end of this month as part of the MTA’s extensive action plan to fix the ailing subway system. The 53rd Street tunnel, which connects Manhattan and Queens below the East River, will be closed to facilitate repairs.

What that means for commuters: Beginning at 5 a.m. on December 26, there will be no M train service whatsoever, and E trains will be re-routed via the F line from West 4th St in Manhattan to Jackson Hts-Roosevelt Ave in Queens. E trains will run normally from West 4th to World Trade Center. The subway stop at 5th Ave-53rd St will also be closed completely.

The MTA has pledged to have service back to normal by 8 a.m. on December 31—when approximately a million people will converge on Times Square for the city’s New Year’s Eve festivities.

According to the MTA, the closure “will allow us to perform critical maintenance that helps improve subway reliability,” and during that time, 500 MTA employees will be working non-stop to get the repairs in place.

The MTA has also created a handy little video that explains all of the service changes in detail, which you can watch below: