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Comment by elfchief | Hacker News Reader

Yeah, this is really weird to me. They're talking about installing sensors on particular tracks and the like, after saying that it's GPS-based, but... why? Stick a GPS on the engine, load a database of maximum speeds, get instant safety. What'm I missing?

(Yeah, you have to integrate with the engines themselves, but that seems like not a 6-year project, and especially not once it's been designed and tested. It probably also won't account for "stop, there's something else on the tracks", but just speed-checking seems like it would be a massive reduction of risk with very little complexity...)

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Allowed speed is not as simple as just where you are; it also depends on the trackside signals and how the track in front of you is lined and/or occupied. For example, if you are 1 mile from an interlocking you might be able to proceed at track speed because you will be going straight through it (clear signal) or you might need to slow down to, I.e., 20 mph as you are going to go through a switch to another track (approach diverging signal). One of the main complexities of PTC is getting all that signaling data onto the locomotive, combined with the route and rules, so that it can actually make the right decision. (Keep in mind that on the US's relatively slow freight railroads "cab signals"; I.e. seeing signal indications in the cab of the locomotive, is relatively uncommon. Signals are generally trackside only and are also often 50+ years old. They work fine, but they're not exactly networked in any modern sense. Updating all this trackside equipment is one of the primary costs of implementing PTC.)

Even an app on the driver’s phone that alerts when they’re exceeding the speed limit would have prevented many of the recent crashes because the drivers weren’t incapacitated - just distracted or confused. Many recent cars also know when you’re driving over the speed limit and display an alert. Not billions of $

An AP Press reprint: http://www.dailyfreeman.com/general-news/20171219/engineer-i...

> Engineer in fatal Amtrak derailment might have been distracted by trainee in locomotive

> Investigators are looking into whether the Amtrak engineer whose speeding train plunged off an overpass, killing at least three people, was distracted by the presence of an employee-in-training next to him in the locomotive, a federal official said Tuesday.

> The official, who was not authorized to discuss the matter publicly and spoke on condition of anonymity, said investigators want to know whether the engineer lost “situational awareness” because of the second person in the cab.

Just distracted or confused is a real possibility that is being looked into.

In which case a standard attention system would have worked. The ancient ATS that just stops the train when not cleared.

There is a publicly visible website referenced in some of these articles that showed the trains speed moments before the crash. I believe they also have speed limit information. I wonder if it's possible to write a simple service that consumes this data, compares live train speeds to speed limits and sends an email to Amtrak. Could it be done in the time it takes to ride the train from Seattle to Portland? Quite possibly.

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