The player will have to use a tram to traverse certain sections of the level.
The abandoned railway tunnels are labyrinthine, and difficult to traverse on foot due to the hazard posed by the electrified rail. In the first section of the rail system, Gordon finds himself alone with hoards of Xenian aliens; a lone HECU Marine attempts to keep dozens of headcrabs at bay, and Gordon needn't confront him.
After Gordon has activated and traversed a tram lift, he finds that the upper level has been occupied by the HECU. Gordon spends the remainder of the chapter engaged in fast firefights in the cramped tunnels, dodging their rockets, and avoiding the traps they've set, occasionally fighting the odd Xenian alien that teleports into the tunnels.
