First, this type of utility questions are kind of bullying people's morals, rather than solving problems. For example, the solution to this problem is really: better transportation system.
Second, I'm never capable of such sharp utility assessment in real-life examples of such situations. Everything happens too fast. In the books, in the movies, in plays, operas and ballet, the story tellers tend to persuade the public of such moral choices of reality. In practice, it's more of a story-telling than reality. In reality, I will have to make a decision so quickly that I wouldn't even understand how it happened, and what happened. I may save both of us, or end up killed, or fail both of us, or remain paralyzed by the shock. Whatever I'd do, it would only plague me with guilt or unnecessary pride, if my culture teaches me that such types of assessments are relevant. They are not.