So, I was thinking about quick and easy defence mechanisms that could impede an impending zombie assault. Barricading yourself in a house or secure building is obviously good way of keeping yourself safe, but how long can you stay holed up in the safety of your home/base/fortress?
For the majority of survivors, leaving the safety of home to scavenge for food/water/supplies will be fundamental for survival. It's fair to assume that not everything you may require for long term survival will simply be a case of smash and grab. So how do you hold down a large area - lets say an entire building, in an area where the zombie populace density is relatively high?
In this scenario, the zombie's are the
archetypal zombie, in that; they have very low intelligence levels, don't cover ground particularly quickly, and they have generally poor mobility and dexterity. It's important because you will want to exploit these weaknesses when building your defence.
There will be a tendency to want barricade yourself in the building but this has its issues. Firstly, Zombie's are considerably more dangerous in a close quarters scenario, especially in numbers. If any point of your barricade fails, you're in an extremely dangerous position, you're trapped in an enclosed space, and you're potentially surrounded making an escape effort extremely difficult.
It would be better to take the fight out in the open where you have room to manoeuvre and take advantage of the fact you are much faster and agile than your attackers. It takes a significant amount of zombies to encircle a fit human in a completely open space, but running away from them won't stop them from entering the building you are trying to secure.
As is often said, attack is the best form of defence, and in this case, it is. however holding down a large building can be a very tough task for just a few people especially as you may have a large number of zombies to kill. If you have a ranged automatic weapon with lots of ammo, this shouldn't be too hard. What if you don't have that, or in fact don't have a gun at all? If your weaponry consists of melee weapons and a few petrol bombs, then your approach needs to be different. You need to focus on getting the zombies in groups, as they present the biggest threat, but also the best opportunity to take down as many as possible in the shortest time frame. These are were your petrol bombs come in, using them sparingly to get the large groups of zombies. The melee weapons are used to take down the idle zombie's as using them against groups of zombie's leaves you vulnerable to encirclement.
An emphasis needs to be placed on slowing the zombies assault down, the quicker the zombies can traverse the distance between your visual horizon and the building you're defending, the more dangerous they are, particularly in an urban environment where long sight-lines are obscured by buildings. Since you don't have time to erect a fence as your perimeter defence, you need quick and simple deployable obstacles which impede and can allow you to channel the attacking zombies, into a position that makes them vulnerable. These can also be used to help shape an escape route for you when the time is right.
If you are at a shopping mall, you could try using shopping trolleys as quick and easy movable barriers, while not ideal, they are relatively quick and easy to move into place between two people, where else are you going to find what is effectively a long moving wall? If there are no trolleys to hand, or you want a more comprehensive line of defence, then a great yet simple solution is a trip-wire, not the ones that are attached to explosive devices, but a simple length of long and relatively strong wire.
A knee high trip wire presents an incoming zombie with a few problems. Firstly it has to decide if if it wants to go over it, or round it. If it chooses to go round it, it delays its approach to the building. During this time you may have the opportunity to attack it from the the other side of the wire, this puts a barrier between you and the attacking zombie making a safe disposal of the attacker easier. If you have wires fully encircling your perimeter then this works primarily as a delay tactic. You could also leave a small manageable opening in your perimeter, to bait the zombies into the easy option, ensuring its an area which gives you the advantage.
If the zombie chooses to go over the trip wire the zombie will be in an extremely vulnerable position for a significant length of time. Since Zombies are not the most dexterous of creatures, a trip wire presents a pretty significant obstacle. If they choose to go under it, they would have to crawl or lie down to go under it, this is obviously a great opportunity to take out the immobile attacker quickly and safely with an axe or the like. Attempting to go over it will in most cases result in the zombie tripping and falling, or getting caught on the wire, in either of these scenarios, the zombie is in a vulnerable position.
If its possible, it may be an idea to have multiple trip wires on the same plane, to prevent the crawling under option, whilst having even higher wiring to make getting past a long a difficult exercise for a zombie. The trip wire option may not be possible in all scenarios as a good rigid pole or the likes is required to attach the wire too. In an urban setting this shouldn't be a problem with all manor of street lights and sign poles available. For grassy areas, your own poles could possible be stuck into the ground, with the advantage of you having more freedom to position your wire, however poles that have been pushed into the ground may fail if a heavy zombie falls on the wire. Improvisation will be required to make a successful perimeter. Another reason why the trip wire is good, is because it is very easy to find, and providing it is strong an can be tied easily, you can span a large area with it very quickly and easily.
Even then, the more lines of defence the better, when a line of defence fails, the ability to fall back to an extra line of defence, gives you a bit of time to re-group and do whatever else may be necessary in this short space of time. The final line of defence is of course the building itself, which should be fully barricaded. The role of the buildings defence is simply to buy you enough time to escape, if the zombies reach the building its time to escape, no matter whether you got what you came for or not. If the escape isn't immediate the building will soon be surrounded making the escape extremely dangerous. At this point the vans/trucks need to have been fully loaded already and ready to go. This needs to be a secure area, if the building itself has a garage then it is much safer to have them loaded up in there. If you've made a fully encircling perimeter defence, then obviously the vehicles need to be outside it in order to escape. As long as there are no people inside or stood by the vehicles, then there is no reason for the zombies to gravitate towards the vehicles when there are much greater distractions such as people.
Simple tactics such as these could allow you to hold down a large and vulnerable area against a large number attacking zombies, with just a few people, for hours. It would be vital to the longer scavenging exercises where simply running in and out aren't possible. I have plenty more ideas but i think I have rambled on enough for the one post.
Besides, I've been told that AK-47's the assault rifle you want. This zombie survival guide book even touched on that. 
