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Comment by jbay808 | Hacker News Reader

> The problem with automation is that in order to create a completely unattended system, the industry best practice is to install platform screen doors to ensure that nobody can ever enter the tracks.

What...? The problem with non-automated metros is the same! Either way, best practice is to have doors for safety. Several train stations in Tokyo have doors/gates, despite those lines having drivers. Meanwhile, Vancouver's automated metro has no gates protecting the tracks, but a generally good safety record nonetheless. The attendants are mainly there to deal with issues that gates wouldn't solve anyway: medical emergencies, confused passengers needing directions, drunk/violent passengers, etc.

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Vancouver's automated system without platform doors has been in place since 1985, and as you mentioned, has worked quite well.

The key benefit to not having doors is that you can use different train types and consists because the train doors don't have to line up with the platform doors. Platform doors also make future procurement of new trains potentially extremely expensive, because you're pretty much locked into buying a specific type of train.

Or...you could just replace the doors/gates, which is far cheaper, easier, and generally years faster.

The cost of replacing all of the doors in a single transit system would be equal to the cost of one or two trains worth of new cars. (They're very expensive.)

You can't mix/match then though. If you have a training running every 10 minutes and want to go to every 5 you may need to double the amount of trains you have. If there is nothing wrong with the existing trains (they are not wore out) it doesn't make sense to replace them all.

Also it means you need to shut down the entire line for a month or so while you replace the doors in all the stations. Shutting down one station is easier to pull off without losing riders. If tell everyone you are remodeling for a month and here are the buses, your customers will adjust for that month (getting to the station a little early...), but if you shut down the entire line the system doesn't work for most riders and they buy a car and quit riding.

Your comment doesn't make any sense. Doubling the amount of trains don't change the trains themselves, unless you meant doubling the cars per train, which is a much bigger change that would usually require the reconstruction of the stations to handle the doubled length of the trains. That's a multi-year process per station.

In contrast, if you just want to double the frequency of trains, you just need to double the number of running trains. Doors/gates have nothing to do with that.

If you want to double the number of running trains you need to have double the number of trains. The new trains need to have the doors in the same place as the doors on the tracks, you might not be able to buy the same door configuration on new trains anymore.

There are a couple of exceptions, but they are absurd and expensive so I doubt they apply. Maybe you bought too many trains in the first place and they are just sitting unused somewhere and you can use them. Or maybe you run the train, and then let it sit for a long time before turning it around and running again.

I see a middle ground here...

Stream CCTV footage from every platform to a control room. Have operators observe the arrival of every train, and have a big red emergency stop button for when people fall on the tracks.

In a big network, with say 300 stations with a train every 4 minutes in each direction on average, that works out to ~40 operators required to watch those cameras for 10 seconds during each train arrival.

Not-so-advanced image processing could be used to show only the train arrivals at the busiest platforms or where there was most recent movement on the track, bringing you down to 1 or 2 operators.

Thats a lot cheaper than both platform edge doors, and drivers in every train.

That's almost exactly what Vancouver does. Biggest difference is that instead of image processing on the video feed, there's sensors on the tracks at every platform.

Actually Vancouver had no gates at all. The ticketing was automatic and honor based.

Sort of honor based. You could be asked to show proof of payment and would get fined if you couldn't show you had paid.

This was about gates on the platform, not gates to get into the station. Those new station gates have been a complete boondoggle however. Translink spent $200 million [1] on a system which was supposed to save $2 million a year in fare evasion but people just jump through anyway. They try to put a bright spin on this saying revenue went up $30 million, but they don't talk about ridership level increases at the same time. Even if they saved $10 million a year, it would take 20 years to pay for the system, far longer than the useful life of the fare gates.

[1] https://vancouversun.com/news/local-news/translink-still-los...

And the gates are very badly designed! The single-door design can't handle the peak crowds that go through them, and their 'beep' that confirms fare payment is a long monotone whine which makes it impossible to tell if you've paid successfully or the person next to you has, since all the gates are just constantly emitting a high pitched squeak.

/rant

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