> In fact, single-tracking in most of the subway degrades service even more than it technically needs to, due to the inability of the interlocking system to re

> In fact, single-tracking in most of the subway degrades service even more than it technically needs to, due to the inability of the interlocking system to reverse track directions. To single track the MTA has to tie down the stop arms and coordinate by radio, and it is almost never worth it. The MTA does sometimes use single tracking in the East River tunnels, where the interlocking allows the track direction to be reversed. Thanks for adding this - I'd forgotten about that.