About one week ago, I posted a clip from subchat showing a front window view of the new Flushing Line # 7 extension to 34th Street. At 42nd Street and 8th Avenue, the line crosses at right angles the lower level of the 42nd Street - 8 th Avenue subway station. This lower level station is unusual in that it consists of one track and one side platform under a four track busy station. Please find below a map of the Eight Avenue Line from 59th Street to West 4th Street between 1932 and 2006 and a map of the same line from West 4th Street to High Street Brooklyn between the same dates. Both maps were based on data from B. Linder and the track drawing is by J. Elitz.
Source: Linder, B. & Erlitz, J, "Eight Avenue Subway Track Plans" in New York Division, Electric Railroaders' Association, The Bulletin, Vol. 50, No. 1, January, 2007, pp.2-3.