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Comment by amelius | Hacker News Reader

My gut feeling says a lot of fatalities could have been prevented with a physical barrier between both tracks. Shouldn't this be mandatory with high speed trains?

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I think the physics of the situation don't make a barrier feasible: a derailed train going >100 mph is going to transfer a lot of energy to any kind of barrier it impacts, which in turn might exacerbate the situation (by spreading debris).

I think these kinds of accidents are largely mitigated by rail defect monitoring. I know rails in the US are equipped with defect detectors for passing trains; I'm surprised that a similar system doesn't exist for the rails themselves. Or more likely, one does exist and the outcome of this tragedy will be a lesson about operational failures.

In principle only, if a barrier could keep a train on its side of the barrier, scraping along the barrier for a long distance instead of smashing headfirst into it, the energy could be dissipated over a long period of time, preventing fatalities. But what kind of barrier can withstand a train?

This collision happened precisely because of unfortunate circumstance that break in the rail and derailment happened just before the switch leading to the opposite track. Without the "help" of the switch, carriages of the first train likely wouldn't have invaded the second track.

The tracks are less than 3m from each other, a derailed car doesn’t need to get very far to be a risk to incoming traffic.

if they are already doing a poor job maintaining their tracks, what gives you such confidence that they would maintain the barrier properly?

the more you build the more maintenance costs rise.

I’d rather they spent the money ensuring no trains ever left their tracks rather than halving the destruction if they do.

There was a switchover which made the derailed cars of the first train move into the track of the second one, you can't have a wall there anyway.

Pure economics. In Minneapolis the railroad demanded a crash wall to separate the light rail trains from their trains. It runs 1 mile and somehow cost nearly $100 million. This is a 5x increase from the original estimate but still $20 million for a 1 mile wall is a heck of a lot of money

The 20-ton bogie was flung 300m. What do you expect the weight of a whole car to do to such a wall?

You happened to have an opposing train at exactly the point where the train derailed.

That's simply really, really rare bad luck.

Practically anything you can think of is going to be a more effective use of safety resources than trying to contain a derailing high-speed train.

Thank about the change in airflow. The train would use more energy because of having to push air that is trapped by the barrier

Also the issues other comments described, including that any fault in the barrier means a new safety hazard

More practical but still probably unnecessary is having the planned “passes” be where the tracks are separated by some distance.

But that requires the trains mostly always being on schedule.

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