You might think this argument is settled, that clearly, any advantages in ease of movement or concealment afforded by the dark subterranean underbelly of whatever city being overrun with infected zombie monsters you’re in are negated by the close environment and the ever present danger of surprise attack or entrapment in sections of tunnels or hallway. You’d be wrong.
What follows is a point by point argument for utilization of the man-made subterranean spaces existing so frequently, at such a large scale, under most cities. I also offer, first, a few caveats, or, items upon which the functionality of this argument is contingent. They are not many, nor would they be difficult to find, so I believe the integrity of the thesis remains sound.
A) Shotguns and buckshot ammunition. Called ‘trench sweepers’ during World War I, a shotgun with a barrel no more than 20 inches is probably necessary. This combination of weapon and ammunition affords the best chance of hitting a moving target, particularly in enclosed, sub-surface areas of immediate range and during surprise attacks by stray infected.
B) A wide area, portable spotlight, preferably with a rechargeable, hand-cranked battery setup. Illumination is central, perhaps most important, to using underground transit in a city while the zombie apocalypse is raging. Wide area illuminating devices will prove invaluable in the small, claustrophobic, dark, and shadow rich territory beneath the city streets. Definitely an essential.
Why Tunnels are the Way to Go
1. Direct access to communications infrastructure. Locating and communicating with the remnants of humanity will not only help you stay sane in the sunlight devoid reaches of the undercity, but it could actually help rebuild civilization if you are able to organize and aggregate with fellow survivors.
2. Freedom of movement. Vast, multi-leveled, and offering almost universal access to surface locations, the man made world beneath most cities provides an unequaled range of options for movement.
3. Defensive advantages. The confined spaces and passageways beneath street level are highly favorable to a defensive posture. Attacks by infected will be constrained by the dimensions of the environment while also concentrating the undead into tight groups that can be easily decimated with group fire. The predictable, static nature of the underground world also lends ease to planning defensive regimes. Routes can be plotted, traps, ambushes, fields of fire, video, seismic, and acoustic surveillance can be set up, all while permitting a high degree of escape planning.
4. Less zombies. As mentioned in contingencies, the nature of the sub-surface environment and the statistical relationship between surface and sub-surface concentrations of infected ensure that far fewer zombies will make it into the tunnels. Saturation and size of the zombie population will of course rise successively as one moves through layers toward the surface, but, the chances of surface to sub-surface replacement is far less after eliminating a zombie than surface to surface rates of replacement. Visual, auditory, and seismic isolation beneath the surface ensures that any activity, whether killing zombies or making a noisy escape, will attract far less attention than it would above ground.
Sure, trains carrying passengers will likely halt all over the city beneath the streets, its passengers either eaten or now a member of the staggering undead army, and a few may even wander deeper into the underground warren of civilizational sediment, but areas of high concentration can be easily avoided.
5. Sidesteps environmental pressures found above ground. Deep in the bowels of any urban setting temperatures are more stable, precipitation does not fall, and a range of other factors, including air pressure, humidity, and windspeed will remain far more constant. Environmental predictability is important as it reduces the possibility of climatological developments forcing action that may or may not be planned or articulated to its greatest extent.
A Couple Problems
– After humanity disappears into the maw of a violent, chaotic zombie apocalypse the pumps and water management regimes which control groundwater beneath many cities will all fail. As most major cities are located immediately adjacent to significant bodies of water, this means that underground flooding is highly likely. If you take refuge beneath the city streets keep this in mind, continually monitor water levels, and plan an escape.
– Airborne pollutants. Again, once civilization collapses, a distinct possibility exists that serious pollutants will begin escaping their control structures. These types of heavy gases or liquids may concentrate underground so if possible include some form of air filtration while you eek out an existence beneath the city streets, whether that be a device worn on the body or a larger system emplaced in your makeshift home.