THIS exists in M-E?

[Volo]

"The dragon passed like an express train, turned a somersault, and burst over Bywater with a deafening explosion."

"Poor Bilbo couldn't bear it any longer. At may never return he began to feel a shriek coming up inside, and very soon it burst out like the whistle of an engine coming out of a tunnel."

So, what do we have here:

1. "express train like a dragon passing" (with bursts)
It's hard to make a slow caravan of wagons from this. Deffinitely refers to something fast. Though we shouldn't forget the "express"-part which means that the train is for passangers. So it can't be a mine cart either. And the "dragon"-part, doesn't it form the words "smoke" and "long", "big" and "wormish" in your mind?

2. "whistle of an engine coming out of a tunnel" (with bursts)
It is even harder to imagine this refering to anything but a steam engine of a train.

First I thought that this could refer to some invention of Saruman, as seen in the film (if I'm not confusing things), or a mine cart. Now it is pretty impossible to connect this with Saruman or mine carts.

Sorry, Legate, I can only think of something like the train in Harry Potter from the phrases above, and I very much doubt that anything like that would exist in M-e. Though this is an interesting subject!