The electric barrier in Tranzit is a really useful little gizmo you can make to section off choke points very easily for short amounts of time. The components are easily found and the effort for reward really makes it worth it.
First of all, get to the power station, then head up the stairs after the door. In the upper level, you will find a crafting table, and three components scattered around. You need to find a sort of ‘broken table’, which will serve as the base of the zombie slaying trap. Lay it on the crafting table, then find a battery and a small broken TV and craft those onto the base.
Now that your trap is ready, all you need is a source of power for it. Put down a turbine where you want the piles of zombie carcasses to appear and attach the trap right next to it. The trap isn’t huge, but it deals massive damage and the zombies just walk into it. Furthermore, if you can manage to get all four of your team members armed with these you could potentially bring Armageddon to the undead horde.
For more help on Black Ops 2 Zombies Buildables, read our Buildable Items Parts Locations Guide.