[wongarsu]

However PM is a fairly localized pollution that doesn't spread far. I don't think diesel trains that drive through the middle of nowhere are that bad. Near population centers it would be preferable to switch to electric locomotives.

[johnwalkr]

There's a handful of hybrid trains in Japan that are electric in urban areas and use a diesel generator in rural parts of the route.

A quick search didn't reveal any running North America but considering diesel locomotives have mostly used diesel generators and electric motors since the 70s, it's not a stretch to think about implementation there.