The line would then fan out into a bi-level station under Grand Central Terminal with eight tracks, four on each level. South of the station, the four tracks on each level will merge into two storage tracks, with one in each cavern on each level. These storage tracks, which extend under Park Avenue south to 38th Street, will be able to store one , 12-car train. The storage tracks were not part of the original proposal, as they were added in a 2008 modification to the plans for East Side Access.