Points for zombies:
The isolation and dread caused by the entire world turning into flesh hungry monsters, including family and friends
The body horror of being bit and inevitably losing control of your mind and having your body decay (also you can perhaps hide your infection from the rest of the group?)
There are always more, they never stop. Basically turning human persistance hunting against ourselves
Also they just make a good excuse for an apocalypse, with humanoid things to shoot
Connect them together for efficiency, and maybe use both rails for stability and to reduce design conplexity. (you dont even need any additional infrastructure!) Also, have them arrive regularly, so that users don't need to bother with an app! Brilliant!
Seriously though, it's really amazing how people keep inventing trains but worse. I guess this idea makes some sense if there aren't enough riders for regular train service, but still...