Sufficiency Rating:

The bridge sufficiency is a method of evaluating highway bridge data by calculating four separate factors to obtain a numeric value which is indicative of bridge sufficiency to remain in service. The result of this method is a percentage in which 100 percent would represent an entirely sufficient bridge and zero percent would represent an entirely insufficient or deficient bridge.Sufficiency Rating is essentially an overall rating of a bridge’s fitness for the duty that it performs based on factors derived from over 20 NBI data fields, including fields that describe its Structural Evaluation, Functional Obsolescence, and its essentiality to the public. A low Sufficiency Rating may be due to structural defects, narrow lanes, low vertical clearance, or any of many possible issues.

Structural Evaluation:

Structural Evaluation is an appraisal rating that in plain English describes an overall rating of the condition of the bridge structure.This is the summary of the separately rated conditions of the structural components of the bridge. This is the truest measure in the National Bridge Inventory of the structural fitness of a bridge.

This tool would allow survivors to sort data for bridges in their immediate area and chose the most ideal bridge for a long-term stronghold… provided that they plan this out before the electrical grid goes down. The bridge stronghold may not be the ideal solution I thought it once was, but I if you chose your bridge carefully, it doesn’t have to be the rusted deathtrap my coworker makes it out to be.

I’ve been chewing on an idea for a stronghold concept for a bit. The basic theory is that a bridge would be an easily defensible position in the event of a hypothetical zombie apocalypse. While the idea is not without its disadvantages, I think it has a number of significant advantages that I haven’t seen previously addressed in any zombie lore.

1.       Easy to find – While obviously not the most abundant structure, a bridge would be easy to locate in a world without cell phones and GPS. Bridges are over water, and most people are familiar with the major rivers in their respective areas. So find a river, follow it downstream and you are quite likely to come across a bridge.

2.       Strategic value to others – If you are of the mindset that other survivors can contribute to your groups safety and overall survival plan, then a bridge is going to be a natural place to meet other survivors. Positioning yourself on river crossings will increase the chances that travelers will come by you, giving you the chance to increase the numbers of your group. If you feel that other survivors either cannot be trusted, or cannot offer any help to your group, this position gives you an opportunity to ambush them or charge them a toll, supplies in exchange for passage.

3.       Easily defensible – Whether you are defending yourself from other survivors or from zombies hordes, this position is quite different from most traditional strongholds. Elevated above a body of water, you have only two points of access. Major bridges must by definition be located along major highways, which are likely to have a number of abandoned cars. These cars can be repositioned, ideally they still have keys and little gas, or pushed into position to form multiple rows of barriers. Vehicles parked very tightly to each other, blockading the entire width of the bridge will force attackers to have to climb over them, slowing them down and providing additional time for defenders to pick them off, especially with headshots, as attackers peek over the barriers. When the attackers overtake the barrier, they face another, as defenders fall back and continue picking them off.

4.       Safe evacuation route – In the event that all the rows of barricades are overtaken by zombies, or at least it becomes clear that takeover is imminent, the survivors can always escape to the water below via makeshift rope ladders. Ideally the survivors would be able to find and anchor one or several boats nearby, that could provide safe locations to wait out the zombie horde. If the horde does not disperse to levels which can be overthrown, then survivors can always use the boats to seek safe harbor down river.

5.       Renewable supplies – If the bridge is located over freshwater, then survivors can boil water for drinking, and presumably any body of water of significant size would have some sort of fish that can be caught for fresh food.

Now I recognize that most large bridges are located near large population centers which would be a bad place to hole up during the initial outbreak, this is not meant to be a strategy for the weeks of the initial outbreak. This is meant to help survivors regroup and weather a longer term outbreak event.