Past the Jamaica—179th St station on today’s F line is an enormous space built as a provision for the IND Second System. East of the station under Hillside Ave is an underground yard/relay (relays are where trains turn around) which expands into two levels of four tracks each. This relay has the highest train capacity of any terminal in the NYC subway system, with the ability to support 63 trains per hour at peak (though it does many fewer currently).

This massively overbuilt complex was built in this way with the Second System plans in mind. Originally, the Hillside Ave line was planned to extend far past 179th St, all the way out to Springfield Blvd (with later plans calling for extension further up to the county border at Little Neck Pkwy). The lower level of the yard would have been kept as a yard/relay, while the upper level would have continued east on Hillside.

In the end, the Hillside extension never came, so this underground complex is instead used far under capacity. At night, trains come here to sleep, though relays still run through some of the tracks all night. The tunnel has some unique vibes to it. It’s rather dark, and trash from train operators is strewn about near the bumpers at the end of the tracks. The massive scale can truly be felt walking through, and it’s hard not to think of what this place could have been.