Admittedly, that question isn't my favorite, as both options are relatively passive. How do you feel about the situations where a more active role is required? Would you push the man over the railing to save 5?

What if it's pushing a philanthropist onto the rails to save 5 serial killers?

I'm not entirely sure what's the goal of this exercise. I'd imagine that in real life, regardless of who's getting killed, most people would simply let things run their courses since inaction is generally less risky than action.

Then, if confronted, I'd guess most people would probably come up with a justification that was favorable to them (i.e. thay would get them out of trouble's way), not follow some strict ethic model.

I'm not very convinced that the assumption that people have a fixed moral system is correct. It doesn't make a whole lot of sense (evolutionarily speaking) to optimize for some abstract ideal consistency rather than fitting into a group. As far as living in a society goes, telling your social circle that you shun all forms of human killing is one thing, actually making a life-or-death decision when there are tricky caveats is completely different.

You feel this way, but many people will avoid switching the train.

The point of the experiments is to see if (statistically) more or fewer people are willing to switch the train based on the race of the people involved.

And that's why we call it utilitarianism.