Metro started work on replacing three Pentagon station escalators Wednesday, two days after it said it would.

The transit agency was set to begin replacing the three 18-year-old escalators at the south entrance of its Pentagon station on Monday.

"Pentagon officials requested additional time for customer notification purposes, so the project launched this morning after rush hour," Metro spokeswoman Caroline Lukas wrote in an email Wednesday.

Metro officials said previously that it's hard to find parts for the 42-foot-long escalators, and that replacing them all at the same time will make the work go faster.

But Metro gave no deadline for when the replacement would be finished.

The transit agency also recently replaced escalators at Foggy Bottom and Dupont Circle, and announced a $150 million contract to replace or rehabilitate 128 escalators across the system by 2020.