Metro-North is operating on a limited schedule until further notice as crews work to restore full service on three rail lines in and out of the city a day after a fire in East Harlem.

The Metropolitan Transportation Authority said crews are installing six temporary steel columns because the fire caused structural damage to a column. The damaged column is an older design with lattice-like steel, and parts of it date to the initial construction of the viaduct in the 19th century.

Newer columns on the viaduct weren't damaged by the fire, according to the railroad.

Commuters encountered delays and crowding on Metro-North Wednesday. Limited Metro-North service was in effect in and out of Grand Central Terminal, and a Saturday schedule was in effect. Trains were running at reduced speeds of 30 miles an hour, down from 60 miles an hour.

Metro-North encouraged commuters to work from home, and it suggested that commuters who must go to work first check the status of trains before leaving home.

The morning commute proved to be challenging for Joseph Thickpan. "I have to walk three blocks first to get to a subway from here, and then I have to catch my subway, then a bus from here," he said. "It's ridiculous right now."

While service was running close to or on time for most MTA trains early Wednesday morning, transit officials warned about possible crowding later in the day.

Crews worked overnight to assess damage and to make repairs after the fire started Tuesday evening at a garden business under the tracks at the Park Avenue Viaduct at 118th Street.

More than 150 firefighters responded to the blaze.