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Comment by stuaxo | Hacker News Reader

Why would it take 50 years to install signalling across the system ?

This doesn't sound right at all.

The problems with NYC subway signaling have been very extensively covered in previous reporting that you might find interesting:

https://www.nytimes.com/2017/05/01/nyregion/new-york-subway-... http://www.nydailynews.com/new-york/nyc-subway-relies-decade...

"Even something as basic as a cable is an antique.

Workers popped open a junction box to show a 70-year-old cloth-covered cable, due for the scrap heap next year, connected to newer rubber-covered wires."

Basically, the system is so old that an incremental retrofit is very complicated to achieve without full shutdown. Remember the overall NYC subway system is the only train system that actually operates 24-7 so maintenance scheduling is also much more involved.

> actually operates 24-7

Good one. They routinely shut down lines and stations for hours/days at a time. The L got shut down between Bedford & 8th Ave for the entirety of Memorial Day weekend. Even when lines are running perfectly, at night they only run once every 30-60 minutes. To riders the changes feel arbitrary and are impossible to predict. I've been stuck dozens of times in random places because I tried to use the wrong line at the wrong time. The only real way to know there's a problem ahead is to have the privilege of riding that line on a regular basis and reading the signs they post. If you look around almost every station will have posters denoting some change that's ongoing or coming up.

Actually, in much of the system there is a great deal of redundancy so one track can be shut down for maintenance using weekends and 10 PM to 5 AM. For example there are often parallel local and express tracks (6 local, 4,5, express or 1 local and 2, 3 express or C local and A express).

Also entire train lines frequently run in parallel a few blocks from each other.

See: http://web.mta.info/maps/submap.html

I'm not saying I haven't been caught inadvertently as well, but FWIW they actually do a pretty good job of posting all this information on their website.

And in fact Google Maps does a decent job of scraping it as well. You just need to remember that when Google Maps wants you to go to Jay St. Metrotech instead of High St it might not just be because it thinks it's 300m closer.

Then it should close at night. Pretty much every city with a subway system worth bragging about does.

It always seemed strange to me that Philly is the only city I've been to that fully replaces the subway at night with buses.

Part of what makes the subway system worth bragging about is that it runs at night.

I am proud of that as a New Yorker, but I would much rather replace it with buses at night if that would make it actually work during the day.

Why? Surface buses can run quickly at night when there is light traffic, and the air quality is far better at surface level than in the subway.

Even though trains are scheduled through the night, they shut lines down pretty frequently during overnight and weekend hours and replace them with bus service.

>Then it should close at night.

No, it shouldn't, and I take it by this statement you don't live in NYC. I do, and have lived in Tokyo and other cities with excellent mass transit. While Tokyo's system is much, much better, it's pretty fantastic that I know I can always get a train home no matter what time it is, no matter where in the city I am, much faster than any ground vehicle would take me.

Everywhere else just runs replacement buses at night and it's fine. Yeah ok it's a little slower, but it means you're not running a huge train for five people.

Many larger cities in Europe run the metro continually from Friday until Sunday night.

This is a decent compromise.

There are way more than five people per train at any time of the day or night. Besides all the people with night and early-morning jobs, there's also the fact that bars are open until 4 AM. They call New York "The City That Never Sleeps" for a reason.

What city in the US has a subway system worth bragging about? Philly's subway has 3% of the ridership of NYC's. It's not even in the same ballpark.

> NYC subway system is the only train system that actually operates 24-7

Chicago's subway is 24/7, too.

This is only true for the red and blue lines though. And since they only have one track for each direction they must interrupt the service to do maintenance.

It depends on where in the system the maintenance is needed. On the Blue Line they just have the trains share a single track for a while while work is being done on the second track. On the red line, they do the same thing outside of downtown. If the work is being done downtown, the Red Line trains can use the Pink/Green/Orange/Brown/Purple tracks and go elevated instead of underground.

Only the Blue and Red Lines are 24 hours IIRC

You are correct. But that doesn't negate the point.

It's not right, and the explanations about the age of the systems are mostly excuses. There is a good article somewhere, maybe the Atlantic, where the reporter was able to get some MTA managers to admit they were essentially holding fixes to the visible problem (no arrival time signaling) hostage as a means to gather public support and funding for less visible overhaul of the infrastructure, by bundling the two together.

Hard to prove this is the case, but it smells right to me. Modern signaling system that did nothing but give arrival times to the public would not have to make use of any infrastructure at all -- it could run completely independently -- and could be done for a tiny fraction of the billions of dollars that the MTA is spending on the slow work they say is currently necessary to get it.

First they have to make new rolling stock, as the new system only works on post-2000s trains.

Second, MTA estimate about 16 miles of track could be upgraded per year. They have 665 miles of revenue track (850 including non-revenue), so it would take 41.56 years just to convert the revenue track. The Regional Plan Association wants MTA to convert 21 miles of track per year, leading to 31.66 years to cover all the revenue track.

Add the time to create new rolling stock, any additional time for any additional track in the next 30+ years, and extra time in case they go over the original estimation. Easily between 35 and 50 years just to convert the revenue-generating track.

https://en.wikipedia.org/wiki/Signaling_of_the_New_York_City...

> "as the new system only works on post-2000s trains."

Actually, it isn't even all post-2000s trains. The CBTC [2] train controls aren't even on all of the post-2000s trains. In fact besides the 'L' train which has already been converted, only the 7 line has all of its cars as CBTC [1].

This is really bad news, because ideally, the very, very crowded 4,5,6 lines mentioned in the NYT article should be the lines to have the signals computerized, but the 4, 5 trains are relatively "new" having been put in service in 1999-2003 or so. Some of the trains in service are > 50 years old.

[1] https://en.wikipedia.org/wiki/New_York_City_Subway_rolling_s...

[2] https://en.wikipedia.org/wiki/Communications-based_train_con...

1) Much of the system is very old, some of it dating back to the 30s. Replacing those parts is very complicated, it's not a 1:1 process. The improvement comes because new signals work under different assumptions. The current signals are basically automated versions of people standing with flags. Partially interfacing the old with the new is very complicated.

2) Downtime basically shuts down the city. Even nights and weekends interruption in service causes major disruptions. The surface streets are at maximum capacity, there is no way to get that many people in and out of downtown and midtown without the subway.

Why would it take 50 years to install signalling across the system ?

Caltrain is on year 5 of their "3 year" project to modernize their signaling system... and that's a relatively simple 75 mile system with 30 stations and it's almost all above-ground.

the only right way to answer that question involves a 10000 word history of the politics of the MTA, the finances of NY state and NY city, bankruptcies, budget shortfalls, political corruption and misdirection, very messy labor union politics, and the complexities of running a giant subway system 24/7 in a region that suffers significant damage every year from hurricanes and ice storms.

> Why would it take 50 years to install signalling across the system ?

Because currently, the residents would riot over the taxes/fees cost of redundancies required to enable faster maintenance and upgrade projects of a 24x7x365 operating system, where the pain of maintenance is constantly deferred until it turns into a looming, critical safety-liability issue. Back when the population density was lower and the pace of life slower, and less economic dependencies upon this infrastructure, the disruptions were affordable and more palatable, but now there are likely powerful stakeholders pressuring the Port Authority from taking as many outages as they'd like these days, comparatively. When I used to live in NYC, the Port Authority took a lot of abuse from a lot of different quarters for every line shutdown for planned maintenance. Increases in fares to fund future expansion/maintenance was met with a lot of resistance. They were like sysadmins for NYC.

This is the real reason for all of these problems. It's political. The fares don't come close to covering the operating and capital cost of the system. It's not user-pays, it requires constant government subsidies (as an implementation detail, the required government subsidies form a convenient way for the state and city to hold each other hostage, but that's another story).

Any talk of use pays is met with outrage about how low income people out in the boroughs couldn't afford it, so the whole system continues to operate as a horribly inefficient welfare system for poor people to get to underpaid jobs in the city, instead of a transit system. It would help a lot to double (triple?) the fares overnight, and give the poor people out in the boroughs a free metrocard - at least that way you're capturing the value provided to the rich people and tourists all the way through manhattan and brooklyn.

475 stations, 840 miles of track, the signals have to be 'hot patched' as the system still needs to keep running 24/7/365.

50 years might be an over estimate, but projects like these tend to slip their deadlines.

[Edit] peterwwillis's answer is much more thorough than mine https://news.ycombinator.com/item?id=14948951

Just implement speed restrictions (say 5 M.P.H.) in block sections that are being upgraded. Sure it's annoying to have your train slow down, but if you're going that slow you don't really need signals, to begin with.

We're underground. Is there space for the maintenance staff to stand whilst a train passes? Probably not everywhere.

If trains normally average, say, 30mph, and 12 times per hour in one direction, a 0.5mile restriction adds 5 minutes to the journey time. Now we can only run 11 trains per hour -- which messes up the whole schedule.

The periods where there isn't a train passing will be quite small. Is there time to get any necessary equipment onto the track, start the work, then clear the equipment away before the next train is approaching?

What happens if the staff make an error, and break the existing system? It might not be possible for trains to move, in which case we now need to evacuate hundreds of passengers along the tunnel.

Work within metro tunnels while trains are running is, therefore, very unusual.

Ozrtm

Unions.

Care to elaborate?

They're not typesafe, and that slows down refactoring.

The solution, of course, is to rewrite the subway in Rust.

As much as I think unions are an absurd way to deal with income inequality by doing everything terribly and expensively, this is a really unsatisfying answer when it comes to explaining why the US is so bad at infra construction. Freaking Germany and France are hardly famous union-busters, and somehow they manage to be infinitely more efficient than us at public works projects. There's clearly something more complicated going on than "Unions."

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