Just after Columbus Day, Metro plans to begin replacing the two escalators for the Metro Center entrance at 12th and G streets NW. Through spring, riders will need to use escalators at the station’s other three entrances.

Inconvenient as that detour may be for people using the busy downtown station, Metro said that by doing both the escalators at once, the time for the project will be cut in half. In the other escalator replacement recently announced, Metro said it will take up to two and a half years to replace — one by one — the bank of three escalators at the entrance to the Bethesda station. (Bethesda has just the entrance, and a full closing of the station was ruled out.)

The three other entrances at Metro Center are at 13th and G, 11th and G, and 12th and F streets. They all have coverings that protect the escalators from the weather. The project at 12th and G streets, set to start Oct. 14, will include installation of a canopy above the escalators.

The stairs next to the two escalators at 12th and G will be maintained in a usable condition during the project in case they are needed for an evacuation, Metro said.

The escalator replacement program in the Metro system is still relatively new. For years, the transit authority focused on repairing or rebuilding the aging equipment, but riders — and eventually Metro — realized that was a losing battle. The new escalators for Metro Center will be the 26th and 27th replacements. So far, Metro has replaced escalators at Foggy Bottom, Dupont Circle, Pentagon, Van Ness, Georgia Avenue-Petworth and Glenmont. More replacements are in progress at Columbia Heights, Glenmont, Bethesda, Friendship Heights and Georgia Avenue-Petworth.

Extensive as that program has become, it still overs a small portion of the rail system’s escalators. With the opening of the five new Silver Line stations, Metro now has 613 escalators.