4 ms·

This has, of course, been suggested about 37 billion times (judging from the blogs/forums I read...). It's not a bad idea in the abstract, but it's also not a

This has, of course, been suggested about 37 billion times (judging from the blogs/forums I read...). It's not a bad idea in the abstract, but it's also not a trivial and cheap project. The author's example of Japan leaves out the little fact that although it's used on some new lines, and is being retrofitted on some old ones, the vast majority of Japanese rail/subway lines do not use platform barriers, and it will certainly be many decades, if ever, before a significant number do. Besides the obvious construction costs, to make platform barriers work you need very consistent door positioning, which is maybe not so hard for new systems, but is a much bigger problem for old systems like the NYC subway (with multiple types of running stock, etc). NYC has the additional problem that it has much higher (up to an order of magnitude in some cases) construction costs for public works projects than most other countries. On the positive, platform doors are not an "all or nothing" proposition ... they can be added line-by-line, or station-by-station, as soon as necessary conditions are in place. Certainly it's not a bad idea to study for the future, but it's also certainly not a simple project to undertake, and even if started soon, it would be a long time before enough any significant portion of the system is protected.

mithaler 14y ago
I happen to live on the 7 train, so I know a fair bit about the difficulties of installing it there. The 7 train is still controlled entirely manually, with the old block-based signalling mechanism that can only be aware of the location of a train in very vague terms. It's currently having CBTC (Communications-Based Train Control)[0] installed, which will give dispatchers much higher resolution information about the location of every train, and go a very long way towards automating the entire system. CBTC installation is scheduled to be completed in 2016, and it's the reason why there are currently so many service disruptions afflicting it during weekends (it actually just began a series of 13 consecutive weekends during which it will not go into Manhattan). If I recall correctly from the posters, the total budget of the project is about $750 million. If and when the line is fully automated someday, it will become possible to create a reliable barrier mechanism (like what currently exists on the very small automated portions of the NYC subway, which is really just the JFK AirTrain). Until then, human operators can't reliably get the train cars to stop in the same place. [0] http://en.wikipedia.org/wiki/Communications-based_train_control http://en.wikipedia.org/wiki/Communications-based_train_cont...
- snogglethorpe 14y ago
  > If and when the line is fully automated someday... Until then, human operators can't reliably get the train cars to stop in the same place. Note that it certainly is possible to consistently do very accurate stops with only unassisted human operators; Japanese rail operators have done this as a matter of course, AFAIK using simple visual alignment aids, for as long as I can remember. [Traditionally it's done because people are lined up at the door locations (marked on the platforms), not for platform barriers.] It's more a matter of operating culture and training than technology. [Of course changing the latter may be easier in NYC!]

mithaler 14y ago

I happen to live on the 7 train, so I know a fair bit about the difficulties of installing it there. The 7 train is still controlled entirely manually, with the old block-based signalling mechanism that can only be aware of the location of a train in very vague terms. It's currently having CBTC (Communications-Based Train Control)[0] installed, which will give dispatchers much higher resolution information about the location of every train, and go a very long way towards automating the entire system. CBTC installation is scheduled to be completed in 2016, and it's the reason why there are currently so many service disruptions afflicting it during weekends (it actually just began a series of 13 consecutive weekends during which it will not go into Manhattan). If I recall correctly from the posters, the total budget of the project is about $750 million. If and when the line is fully automated someday, it will become possible to create a reliable barrier mechanism (like what currently exists on the very small automated portions of the NYC subway, which is really just the JFK AirTrain). Until then, human operators can't reliably get the train cars to stop in the same place. [0] http://en.wikipedia.org/wiki/Communications-based_train_control http://en.wikipedia.org/wiki/Communications-based_train_cont...

snogglethorpe 14y ago
> If and when the line is fully automated someday... Until then, human operators can't reliably get the train cars to stop in the same place. Note that it certainly is possible to consistently do very accurate stops with only unassisted human operators; Japanese rail operators have done this as a matter of course, AFAIK using simple visual alignment aids, for as long as I can remember. [Traditionally it's done because people are lined up at the door locations (marked on the platforms), not for platform barriers.] It's more a matter of operating culture and training than technology. [Of course changing the latter may be easier in NYC!]