Late by several pages, but, to whoever it was that asked about the train-wrecking statutes and capital punishment, it is indeed on the law books in PA, as a capital offense, but the last person to be convicted and executed for it here was way back in the 1920's/30's (He broke the tracks to derail a passenger train hoping to rob the mail car/injured passengers in the confusion, instead, he derailed a freight and killed the locomotive's fireman.)
Why does it warrant execution? Again, speculation was correct.
Train accidents are messy, carry a potentially high death toll, and due to the hazardous cargo sometimes carried, a great chance of causing a cascading series of disasters, or, as the law words it "risking catastrophe". But it's mostly because the law was written in a time when the railroads were the primary (and in some cases only) form of intercity and interstate commerce and travel, even as recently as right before WW2, your average person didn't always own a car and if they did, there were no such things as highways or affordable coast-to-coast air travel. Most people still took the train, so tampering with the rails was not only a risk to personal life and limb, but a risk to the economy and society in general. It would be analogous to the similarly tough modern federal laws against carjacking and air piracy. Engaging in them is seen as an attack on the country's ability to conduct free trade and the citizen's right to free travel. (And why horse theft was a capital offense in the 19th Century, it was more than running off with your property, it was destroying your livelihood)
Now, since the railroad's scope and place in society has changed greatly since then, the odds of someone breaking that law are less, but it still remains on the books because in practice, laws tend to fall out of disuse and be forgotten about but not removed, as others have noted.
It's very unlikely Len would have been charged under it though, even if he had been successful in derailing a train with fatalities. There's more than enough current law that covers his actions without having to resort to an ages-old statute that would call for a penalty the Commonwealth of PA hasn't used since the late 1990's. In fact, being charged under a law that's laid unused like that for nearly 80 years is grounds for an appeal under the 5th Amendment's "Cruel and Unusual" punishment clause, if there's more modern/common ways to classify the same crime. (To use horse theft again, NOBODY is going to get the chair for stealing a horse these days, even if some western state still has it on the books, they'll get charged with regular old theft and that will be that)
Not that Len couldn't be, or that he wouldn't be successful in an appeal, but, it's just overall unlikely, the train wrecking statute is mostly a living fossil of a different time.