[astrodust]

Insanity? That's dirt cheap. Think about how much mechanical complexity goes into each door, how it has multiple motors, servos, linear actuators and such. It has to be safe when closed, and it has to be safe when opened, it can't spontaneously shut in someone's face or pin them in the middle.

It needs multiple sensors that can handle being exposed to a lot of wear and tear. It needs to operate for years on end with, ideally, very little maintenance. It has to endure being buffeted by the forces of the train entering and leaving the station which exerts significant strain on any hinges or track mechanisms.

So you need a pair of these for each set of doors on the train, and if each car has three doors, and you have eight cars, that's 48 doors.

That leaves you with only $20,800 per door. You still need to build the walls themselves and you need to have this installed by the right technicians.

Do the math, don't bitch just because it sounds expensive.

[djrogers]

It occurs to one that elevator doors are every bit as complex as what you ecan scribe and have been doing their job for over half a century at a cost of far less than that.

But really, you don't even need a door - a simple gate like on a ride at Disneyland, or heck even the gates at the station entrance would do nicely.

[astrodust]

Not many elevators have 48 doors, and those that do cost a shit-ton more than a million dollars.

[refurb]

Sorry, but $20K per door is still ridiculous. This is not new technology, automatically operated doors are used in many different settings. It's pure gov't waste to pay that much. It would be wasteful if it was 1/4 that much.

[Symbiote]

As an example that most automatic doors don't have to deal with, but is essential for railways:

The door must detect a 1-2cm obstruction (e.g. fingers, child's wrist) and be sufficiently weak that a child can pull their hand/wrist free. The door must not prevent a train from departing if only a hem of a skirt/trousers/coat is trapped. They must be strong enough to prevent anyone falling from the train while it is in motion, and must not be able to be forced open between stations.

Otherwise, approximately one person per year will die.

How much would you charge, to make doors to this specification?

And, some time in the next five years, an accident will happen, somewhere in the world. Your next door will need to prevent that situation, too.

[This is the situation in "wealthier" Europe, where it's pretty difficult to die on a train. Other countries may vary.]

[GoToRO]

The first part just means they need to have rubber padding. Still expensive since the design it's a one time job and can be reused for trains, trams, buses etc.

[Symbiote]

It's not that simple. Something different is required depending how the doors close (pneumatic, electric) and the expected use (high / low speed, crowded or not).

If the padding is too squashy, a trapped hand won't be detected and the person could be dragged under the train. Too sensitive, and someone leaning a suitcase on the door prevents the train from leaving.

[Daishiman]

It's a lot, but it's objectively not ridiculous.

[astrodust]

You have no idea how much an elevator costs, do you?