3 ms·

> Being 24/7 just takes redundancy. If you have 2+ lines from A <> B, you can single track them during low demand times and with care take any part of the syste

> Being 24/7 just takes redundancy. If you have 2+ lines from A <> B, you can single track them during low demand times and with care take any part of the system offline without shutting down. Not all lines have four tracks (some only have two), and even for the ones that do, running trains while work is going on means incredibly slow and delayed service.

bdhess 9y ago
I don’t think you understood what parent meant by “single track”: https://en.m.wikipedia.org/wiki/Single-line_working https://en.m.wikipedia.org/wiki/Single-line_working
- chimeracoder 9y ago
  > I don’t think you understood what parent meant by “single track”: https://en.m.wikipedia.org/wiki/Single-line_working https://en.m.wikipedia.org/wiki/Single-line_working I understand what they meant; I'm explaining that even when running trains on dedicated tracks (e.g. the local line is shut down for maintenance, but the express line still runs), it causes delays that many find unbearable. Running trains in both directions on a single track would degrade service even further. At that point, it may very well just be better to shut the entire line down temporarily, which is what they generally do.
  - betterunix2 9y ago
    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. For comparison, the entire PATH system supports changing the track direction, and single-tracking is relatively common during weekends. Of course, the PATH is much smaller and has a different history behind it, not to mention totally different legal requirements (it is a "railroad" rather than a heavy rail system).
    - chimeracoder 9y ago
      > 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.

bdhess 9y ago

I don’t think you understood what parent meant by “single track”: https://en.m.wikipedia.org/wiki/Single-line_working https://en.m.wikipedia.org/wiki/Single-line_working

chimeracoder 9y ago
> I don’t think you understood what parent meant by “single track”: https://en.m.wikipedia.org/wiki/Single-line_working https://en.m.wikipedia.org/wiki/Single-line_working I understand what they meant; I'm explaining that even when running trains on dedicated tracks (e.g. the local line is shut down for maintenance, but the express line still runs), it causes delays that many find unbearable. Running trains in both directions on a single track would degrade service even further. At that point, it may very well just be better to shut the entire line down temporarily, which is what they generally do.
- betterunix2 9y ago
  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. For comparison, the entire PATH system supports changing the track direction, and single-tracking is relatively common during weekends. Of course, the PATH is much smaller and has a different history behind it, not to mention totally different legal requirements (it is a "railroad" rather than a heavy rail system).
  - chimeracoder 9y ago
    > 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.