How would zombies stop a train?

I'm writing a brief short story for an anthology, and the protagonist is on a train to London when the story begins. Half-way through, the brakes come on and the train grinds to a halt. What would have made the driver hit the brakes? This is 20 Minutes into the Future, so I'm considering an AI-controlled locomotive rather than a human driver.

This is a world that has adapted to the zombie threat, by the way, and things like railways and motorways are considered relatively safe from attack.

Just to clarify, these are 28 Days Later/Dead Set type "frenzied runner" zombies, not shamblers.

edited 30th Jul '11 5:15:02 PM by pagad

Anything will clog up if you throw enough mass at it, even well-shielded trains. Actually, all they have to do is get the train off the track- not easy, but certainly far from impossible.

Either that, or the train AI has a function to keep it from running over actual people. How that gets exploited is up to you.

edited 30th Jul '11 5:18:01 PM by deathjavu

If an Ai is running the train with no humans around, it's going to have safeguards built in to have it able to recognize not only humans (things the train could damage) but various things that it would damage the train to hit. A car (or other vehicle) stopped on the tracks, a irregularities in the rails, things that could cause the train to derail or otherwise be damaged if it hits them.

Right-Wing Militia Fanatic / Zombie Advocate / Animal Wrongs / other Political Stereotype of your choice group? Perhaps there is someone or something on the train they want. If society has continued on a relatively large scale and in a relatively civilized manner, there are still bound to be dicks and idiots willing to do such a stupid thing...

edited 30th Jul '11 6:11:44 PM by USAF713

I have a very tight word limit, so I can't go into too much detail. I'm considering leaving it ambiguous, but might hint at what caused the train to stop rather than overtly show it.

Anyway, the idea is that the major transport networks have been fortified with fencing and regular patrols, so successful attacks against them are considered unlikely.

Well, no technology is immune from simple mechanical breakdowns, not even in the future. If that doesn't seem like too much of an overt Deus ex Machina (pun intended, as I don't think that's an entirely appropriate use of the term), you could go with that.

Unless it has to be a deliberate effort, in which case some kind of sabotage by a lone nutter isn't out of the question.

edited 30th Jul '11 6:54:40 PM by deathjavu

If I were designing a software system for a train, I would fail-close (stop the train and give out a red status) for any problems that come up. Especially for trains, this would mean that anything that gives red status on a track:

• there's objects on the track
• the tracks are out
• unable to obtain status of the tracks
• the system or AI shuts down

And so on (and probably others, since I'd never worked on railroads before I might be missing something).

So for zombies to stop it, they merely need to clog up the track causing a red status and the train would stop rather than risk derailment. Now, if the world is zombie infested, I would also program the train to back off away from the problem zone. As well, since a stopped train is dangerous in a zombie infested area, I might also tie the system with local authorities to immediately inform them of a stopped vehicle, just in case they need to perform a rescue operation.

edited 30th Jul '11 7:03:52 PM by breadloaf

Yeah, about that, even if the train stops, how are the zombies going to do anything? If anyone in this setting is competent, that train is armored and, hopefully, armed, as well as sealed from the outside as best as possible. Zombies that aren't supermutated (like Left 4 Dead) shouldn't have a chance to get in, and even then...

edited 30th Jul '11 7:28:53 PM by USAF713

People act like idiots in emergency situations. It's entirely possible that one of them flips out and opens the door for some foolish reason. Panic, or clausterphobia, etc. Esp. considering fortified trains wouldn't have as much in the way of windows.

a whole bunch of bodies makes a helluva barrier. Oh, and trains are claustrophobia-inducing tiny. Maybe someone decided to play hot potato with the virus.

And why isn't there an auto-seal on the door, again? Assuming that this isn't one of those viruses that can turn you without physical contact (airborne is no fun and no fair), the doors should automatically lock and be unable to be opened except by the armed guards, who should be trained to know when to open them and when not to, and who should be able to defend themselves from force. They should also be the only ones able to open the doors.

Come on now, is it really that hard? We could do this today, if we wanted. 20 Minutes into the Future, they should have auto-turrets, too, or at dead least some kind of weaponry on the outside of the train that they can use. Shit, if they wanted, they could just electrify the outside and fry the shit out of the zombies. Headshot-necessary or not, they won't be walking if they're fried.

My thoughts would be to have the tracks blocked by another train, where someone with the virus got on board, turned, and infected the rest of the passengers. The second train can then stop, zombies can pour out of the first train and surround it. Simple.