FrontFrank, I apologize in advance for repeating what you already know.
Until 1976, the tracks from Red Bank down to Lakewood (and from there to Bridgeton and beyond) were owned and operated by the Central Railroad of NJ (CNJ for short, also the "Jersey Central" RR). The CNJ called that route their "Southern Division".
In 1976 a new company Conrail (CR) was formed to take over most of the tracks of most of the bankrupt northeast RR's, including the CNJ. The CNJ Southern Division became known as the CR Southern Secondary. Hence the thread title.
Conrail's nickname was "Big Blue", due to the blue locomotives you mention. Around 20 years ago (someone here will know) CSX and NS together bought Conrail. They divided most of it up between them, but locally in NJ and the Philadelphia area they kept Conrail to operate some local tracks, including the Southern Secondary. NS and CSX often supply locomotives to Conrail so you see them being used on the CR Southern Secondary. (Well, at least the CSX ones these days for reasons described above.) I don't know the last time a "Big Blue" CR loco was on the Secondary.
Last edited by pumpers on Thu Jan 27, 2022 8:23 pm, edited 2 times in total.