What is the meaning of trains in a dream?

During the last 4 nights I had 3 dreams involving trains.

The first dream started on a railway station, when suddenly a train came rushing by at about 300 mph, just barely missing me.
In the second dream I was slowly being crushed to death between a train and a wall.
In the third dream I had just killed 60 people with a friend of mine, and after that we got on a train back home.

I have read other threads on this website about people who also suddenly have a lot of dreams featuring trains. But none of those threads mention what this means.
So I was wondering, is there any meaning to suddenly having a lot of dreams featuring trains?

In my opinion:

There is not, as many people think, an encyclopedia of dream symbols. A train in one person's dream may mean one thing for that person, it may mean something else for someone else. Even for the same person, a train might mean one thing in one dream, then mean something else in another dream.

To decode the symbolism, you must have have 2 things. First, you need good enough recall to have all the dream facts so you aren't overlooking any clues. Second, you need to have a good understanding of yourself - your ambitions, fears, challenges, successes etc...