Perhaps not technically a railroad, but not an adventure I'd ever use.
Starts out with three "optional" encounters - all fights - and notes on how to add a fourth optional connected enemy (who's a dangerous human intended to be a recurring threat throughout and after this adventure, yet not given any name or hint of personality - just combat stats).
Then another fight. Then two more fights, and an optional fight. Then... fights? And more fights!
There's no map, because no map is necessary, because it's a railroad. There's no scope for players to make an informed choice that has an effect on the outcome, except for how they fight the things they're foreordained to fight. During the adventure the players never have a choice, it's just assumed they're always pressing "onward".
There are quantum ogres lurking - if the players lack a certain useful item, for instance, the DM is encouraged to add some to the loot they got earlier, rather than expecting them to problem solve or to not achieve some part of the story that the author has dreamed up. There are things left up to the GM: the players get however much treasure the DM thinks they should but not more than 200gp each. There are unexplained mechanical effects - if the characters hang around too long, they get scared, but there's no game-world justification for why they're getting scared, nothing that would make sense to a character.
The creatures could be useful, and the magic items at least have some individuality, but that's 9 out of 44 very wordy pages.