4 ms·

I still don't understand why the signal system takes so long to upgrade. Can't they install most of the new system while the old one is still working on the sa

I still don't understand why the signal system takes so long to upgrade. Can't they install most of the new system while the old one is still working on the same tracks? And isn't digital signalling available from contractors that have already done the work in other cities?

lr4444lr 9y ago
No downtime. The system runs 24/7/365.
- CoolGuySteve 9y ago
  I'd believe you if my local R line wasn't shut down every weekend for the next year.
  - lr4444lr 9y ago
    Precisely my point: no regularly scheduled downtime to do these things results in major outages when the situation gets too bad to ignore. Same with the impending L-train shutdown.
- strictnein 9y ago
  Is it impossible for them to schedule downtime?
  - smelendez 9y ago
    They do. They do some work on nights and weekends, and some lines have shut down and will shut down for periods of months. The L train (Manhattan to Brooklyn) is scheduled to shut down for over a year to do residual repairs from Hurricane Sandy's flooding. But it's a major pain. The system is at capacity many hours of the day, as are surface roads, and some points in the city are only near one line, so there's no easy way to get people where they need to go when their train can't run.
- nine_k 9y ago
  But parts of the systems do shut down time to time, by rerouting trains, or by just canceling them and providing shuttle buses. It's perfectly possible to get 8-12 hours long uninterrupted work windows for significant stretches of the railway. The work has to be incremental, of course.
  - jcranmer 9y ago
    Incrementally redoing the signal system is difficult, particularly because the system has lots of branches and reverse branches--which means you have to basically have it enableable on the entire system before you can enable it, rather than doing lines at a time.
    - nine_k 9y ago
      Difficult, of course. But not impossible, and not specifically because trains cannot be stopped for doing work. Most of the tunnels have 4 lines, so half the line can be worked on while the line still operates; this is being done all the time.
    - betterunix2 9y ago
      Except that the MTA is doing it on sections of lines at a time. It is actually not hard, because the equipment does not have to be aware of things beyond whatever sections of track it controls (otherwise, any upgrade would require national coordination, since most rail systems, including the NYC subway, are connected to the national rail network).
- js8 9y ago
  That's interesting. In Prague, subway (which is IMHO superior to NY subway in some ways) is closed every day from midnight till 5 am (roughly, I think it is extended by an hour during weekends). Instead, we have night trams and buses, so the downtime is not a big deal. Maybe a change of culture would be helpful?
  - smelendez 9y ago
    That's what most US cities do, too. Chicago has some all-night rail service, but it's mostly just buses, for instance. But in NYC, an advisory group suggested that recently, and people hated the idea. The problem is traffic can be heavy even after hours, especially on the weekends, so buses would be a lot slower. Lots of people rely on the subway at all hours of the night.
    - phil21 9y ago
      > Chicago has some all-night rail service, but it's mostly just buses, for instance. Anyone that can tends to avoid (e.g. prefers to live off the red/blue line) the lines that do not operate 24x7. Not providing universal service means you lose peak time ridership as well, as witnessed by ridership numbers on those lines.
NikolaeVarius 9y ago
NYC signal systems is extremely complex and old. 24/7 nature makes it hard to do proper maintenance. Old signal system requires nonstop maintenance to keep it running, and it needs to keep running while new system is installed which is extremely expensive. Tons of politics involved too. https://www.theatlantic.com/technology/archive/2015/11/why-dont-we-know-where-all-the-trains-are/415152/ https://www.theatlantic.com/technology/archive/2015/11/why-d...
- betterunix2 9y ago
  It is not all that expensive to operate the old system while the new system is installed. They throw a burlap sack over the new signals until they are ready to activate them, and otherwise the old system just remains in use and costs exactly what it would cost without the new system being installed. The old system has become somewhat more expensive because replacement parts are not needed anywhere else. Originally it was all standard railroad equipment and the same interlocking machines were used on other regional railroads (including freight lines). Since the MTA is among the last users of those machines, they have to fabricate some of the parts or special order others. That said, the old system is pretty reliable and does not require "constant maintenance" beyond what a railroad generally requires. Its shortcomings are mostly in its inability to run trains more closely together, its inability to identify which train is in which block, and its inflexibility with regard to track directions. Otherwise the maintenance is mostly replacing light bulbs and vacuum tubes, and rarely having to replace mechanical parts. In theory the lightbulbs and vacuum tubes could be replaced with solid state components, but in practice there would be no point -- you might as well just replace all of it with solid state equipment, which the MTA is (slowly) accomplishing.
chimeracoder 9y ago
> I still don't understand why the signal system takes so long to upgrade. Can't they install most of the new system while the old one is still working on the same tracks? They could, technically, but the TWU won't let them. The TWU has used signal upgrades as a perpetual carrot for decades - anytime people talk about improvements, they say "well, we need to do X first, so we can upgrade to the most modern signal technology in Y years." If they upgraded the signals, they'd lose this leverage, so instead it remains eternally Y years away.
- betterunix2 9y ago
  I call BS. The TWU has no say over signal upgrades and the MTA has not even hired union members to install the new signal system. The more likely answer is that the MTA has hired shady contractors who did incompetent work for years.
  - chimeracoder 9y ago
    > The TWU has no say over signal upgrades The TWU has immense leverage over the projects that get prioritized. In fact, of the six suggestions that the article lists for fixing the subway, the TWU has actively fought against five of them. > and the MTA has not even hired union members to install the new signal system. This is an issue that's been going on for decades. Talking about what's happening in 2017 with the new signal network misses the entire point of why this project wasn't completed back in the 90s.
    - betterunix2 9y ago
      You seem to think the TWU has power that it really does not have. The MTA has been consolidating the subway system's towers since the 1970s, closing a number of the electromechanical towers and replacing them with transistorized (and now computerized) equipment. In the 90s and 00s they had a grand plan to create a single control center for the whole system, but they hired incompetent contractors who failed to deliver, so now they are back to the old approach of building new towers to replace multiple old towers. At no point has the TWU stopped them. All the TWU can do is stop the MTA from eliminating jobs, they cannot stop the MTA's plans to install new equipment.
crocal 9y ago
Overlaying signalling systems is a complex issue for 2 reasons. First, you have limited track and train access because the train is running at capacity. Second, you can actually create unsafe situations by combining two systems that are actually safe by themselves.
niftich 9y ago
Generally, all 'train control' systems take a long time to roll out. Despite often seeming like one product you 'install' from one vendor, it's really more of a 'solution' that requires a bunch of things you deploy together, and parts of it are delivered by subcontractors. For the relatively simple system that the NYC began using -- Siemens Trainguard MT, used in some other cities, and also on PATH -- you need trackside beacons, lots of wiring (and a good amount of wireless), in-car computing units in the IT closet, in-cab signalling, on-car sensors, in-car wiring, etc [1], a bunch of IT integration and troubleshooting; not to mention "soft deliverables" like conductor training, maintenance training, dispatcher training, safety and bureaucratic approvals, and lots of testing. Even if you assume that all parties are competent and are acting in good faith, this still takes time. In a recent thread about the Amtrak Cascades derailment [2], a conversation about (positive) train control ensued, and some people who worked on such implementations also talked about why these projects tend to be complex. [1] http://www.mobility.siemens.com/mobility/global/SiteCollectionDocuments/en/rail-solutions/rail-automation/train-control-systems/trainguard-mt-en.pdf http://www.mobility.siemens.com/mobility/global/SiteCollecti... [2] https://news.ycombinator.com/item?id=15968720 https://news.ycombinator.com/item?id=15968720

lr4444lr 9y ago

No downtime. The system runs 24/7/365.

CoolGuySteve 9y ago
I'd believe you if my local R line wasn't shut down every weekend for the next year.
- lr4444lr 9y ago
  Precisely my point: no regularly scheduled downtime to do these things results in major outages when the situation gets too bad to ignore. Same with the impending L-train shutdown.
strictnein 9y ago
Is it impossible for them to schedule downtime?
- smelendez 9y ago
  They do. They do some work on nights and weekends, and some lines have shut down and will shut down for periods of months. The L train (Manhattan to Brooklyn) is scheduled to shut down for over a year to do residual repairs from Hurricane Sandy's flooding. But it's a major pain. The system is at capacity many hours of the day, as are surface roads, and some points in the city are only near one line, so there's no easy way to get people where they need to go when their train can't run.
nine_k 9y ago
But parts of the systems do shut down time to time, by rerouting trains, or by just canceling them and providing shuttle buses. It's perfectly possible to get 8-12 hours long uninterrupted work windows for significant stretches of the railway. The work has to be incremental, of course.
- jcranmer 9y ago
  Incrementally redoing the signal system is difficult, particularly because the system has lots of branches and reverse branches--which means you have to basically have it enableable on the entire system before you can enable it, rather than doing lines at a time.
  - nine_k 9y ago
    Difficult, of course. But not impossible, and not specifically because trains cannot be stopped for doing work. Most of the tunnels have 4 lines, so half the line can be worked on while the line still operates; this is being done all the time.
  - betterunix2 9y ago
    Except that the MTA is doing it on sections of lines at a time. It is actually not hard, because the equipment does not have to be aware of things beyond whatever sections of track it controls (otherwise, any upgrade would require national coordination, since most rail systems, including the NYC subway, are connected to the national rail network).
js8 9y ago
That's interesting. In Prague, subway (which is IMHO superior to NY subway in some ways) is closed every day from midnight till 5 am (roughly, I think it is extended by an hour during weekends). Instead, we have night trams and buses, so the downtime is not a big deal. Maybe a change of culture would be helpful?
- smelendez 9y ago
  That's what most US cities do, too. Chicago has some all-night rail service, but it's mostly just buses, for instance. But in NYC, an advisory group suggested that recently, and people hated the idea. The problem is traffic can be heavy even after hours, especially on the weekends, so buses would be a lot slower. Lots of people rely on the subway at all hours of the night.
  - phil21 9y ago
    > Chicago has some all-night rail service, but it's mostly just buses, for instance. Anyone that can tends to avoid (e.g. prefers to live off the red/blue line) the lines that do not operate 24x7. Not providing universal service means you lose peak time ridership as well, as witnessed by ridership numbers on those lines.

NikolaeVarius 9y ago

NYC signal systems is extremely complex and old. 24/7 nature makes it hard to do proper maintenance. Old signal system requires nonstop maintenance to keep it running, and it needs to keep running while new system is installed which is extremely expensive. Tons of politics involved too. https://www.theatlantic.com/technology/archive/2015/11/why-dont-we-know-where-all-the-trains-are/415152/ https://www.theatlantic.com/technology/archive/2015/11/why-d...

betterunix2 9y ago
It is not all that expensive to operate the old system while the new system is installed. They throw a burlap sack over the new signals until they are ready to activate them, and otherwise the old system just remains in use and costs exactly what it would cost without the new system being installed. The old system has become somewhat more expensive because replacement parts are not needed anywhere else. Originally it was all standard railroad equipment and the same interlocking machines were used on other regional railroads (including freight lines). Since the MTA is among the last users of those machines, they have to fabricate some of the parts or special order others. That said, the old system is pretty reliable and does not require "constant maintenance" beyond what a railroad generally requires. Its shortcomings are mostly in its inability to run trains more closely together, its inability to identify which train is in which block, and its inflexibility with regard to track directions. Otherwise the maintenance is mostly replacing light bulbs and vacuum tubes, and rarely having to replace mechanical parts. In theory the lightbulbs and vacuum tubes could be replaced with solid state components, but in practice there would be no point -- you might as well just replace all of it with solid state equipment, which the MTA is (slowly) accomplishing.

chimeracoder 9y ago

> I still don't understand why the signal system takes so long to upgrade. Can't they install most of the new system while the old one is still working on the same tracks? They could, technically, but the TWU won't let them. The TWU has used signal upgrades as a perpetual carrot for decades - anytime people talk about improvements, they say "well, we need to do X first, so we can upgrade to the most modern signal technology in Y years." If they upgraded the signals, they'd lose this leverage, so instead it remains eternally Y years away.

betterunix2 9y ago
I call BS. The TWU has no say over signal upgrades and the MTA has not even hired union members to install the new signal system. The more likely answer is that the MTA has hired shady contractors who did incompetent work for years.
- chimeracoder 9y ago
  > The TWU has no say over signal upgrades The TWU has immense leverage over the projects that get prioritized. In fact, of the six suggestions that the article lists for fixing the subway, the TWU has actively fought against five of them. > and the MTA has not even hired union members to install the new signal system. This is an issue that's been going on for decades. Talking about what's happening in 2017 with the new signal network misses the entire point of why this project wasn't completed back in the 90s.
  - betterunix2 9y ago
    You seem to think the TWU has power that it really does not have. The MTA has been consolidating the subway system's towers since the 1970s, closing a number of the electromechanical towers and replacing them with transistorized (and now computerized) equipment. In the 90s and 00s they had a grand plan to create a single control center for the whole system, but they hired incompetent contractors who failed to deliver, so now they are back to the old approach of building new towers to replace multiple old towers. At no point has the TWU stopped them. All the TWU can do is stop the MTA from eliminating jobs, they cannot stop the MTA's plans to install new equipment.

crocal 9y ago

Overlaying signalling systems is a complex issue for 2 reasons. First, you have limited track and train access because the train is running at capacity. Second, you can actually create unsafe situations by combining two systems that are actually safe by themselves.

niftich 9y ago

Generally, all 'train control' systems take a long time to roll out. Despite often seeming like one product you 'install' from one vendor, it's really more of a 'solution' that requires a bunch of things you deploy together, and parts of it are delivered by subcontractors. For the relatively simple system that the NYC began using -- Siemens Trainguard MT, used in some other cities, and also on PATH -- you need trackside beacons, lots of wiring (and a good amount of wireless), in-car computing units in the IT closet, in-cab signalling, on-car sensors, in-car wiring, etc [1], a bunch of IT integration and troubleshooting; not to mention "soft deliverables" like conductor training, maintenance training, dispatcher training, safety and bureaucratic approvals, and lots of testing. Even if you assume that all parties are competent and are acting in good faith, this still takes time. In a recent thread about the Amtrak Cascades derailment [2], a conversation about (positive) train control ensued, and some people who worked on such implementations also talked about why these projects tend to be complex. [1] http://www.mobility.siemens.com/mobility/global/SiteCollectionDocuments/en/rail-solutions/rail-automation/train-control-systems/trainguard-mt-en.pdf http://www.mobility.siemens.com/mobility/global/SiteCollecti... [2] https://news.ycombinator.com/item?id=15968720 https://news.ycombinator.com/item?id=15968720