Yes they do spawn within the tunnels. they have quite a high spawn rate too, so be prepared for a fight!

weird i wandered for a bit and dint see any zombies

引用自 Zack_Batcountry：

weird i wandered for a bit and dint see any zombies

Because the sections of subway and tunnels are really large buildings stacked together. some of the buildings will be empty of zombies at the start of a playthough. as you progress through the game more will spawn in I promise.