Defense – Obstacles Part IV: More On Roads And Bridges

In the last entry we covered what man-improved obstacles were and some ways we could cut (severe) trails.  In this entry we’re going to examine another (and probably easier) way to block trails and bridges.   I’m also going to present some considerations you need to take into account when making the decision to place such obstacles.

The next type of obstacle I’m going to cover is an Abatis.  For our purpose an Abatis is an obstacle  that is formed by a group of trees cut down to interlock blocking a road, trail, or approach path for a vehicle.  As always this kind of obstacle won’t really slow down a threat on foot however it is pretty good at slowing down and temporarily halting vehicles.  Let’s take a look at a diagram that I’ve annotated from an Army manual:

As always the red arrow marked THREAT is the threat’s direction of travel down that road.  This kind of obstacle is created with the tip (treetops) facing the direction the threat is coming from.  The trees have been cut down in the order listed by the boxed numbers to make an interlocking obstacle that when pushed on by a vehicle tends to pile and tighten versus just being swept aside. Also notice the trees are cut down while being left attached to their stumps.  This further compounds the difficulty in clearing this kind of obstacle because trees still connected to their stumps aren’t easily moved.  In the picture it appears that the foliage has been cleared – that’s pretty much just for clarity.  Leave those branches and debris in place as they’ll help frustrate someone trying to clear the obstacle.  This kind of obstacle is a pain to deal with – it’s going to either take heavy equipment (like a dozer)  or guys with chainsaws and trucks to clear.  And it’s not going to be a fast operation unless the threat has considerable resources.  It’s also probably going to be noisy – possibly giving you some warning (but don’t count on that).  If it were me and I had elements on the approach for an assault on the homestead at this point rather than fight through the obstacle I’d dismount.  So the obstacle would have accomplished a basic goal of disrupting my mounted movement and reducing my speed in the assault.  Here’s a top down view of an Abatis cut along a straight trail:

By having those trees interlocking and the foliage still on them very few vehicles are going to easily bypass this.  And if they have a plow on one of their trucks when it starts shoving on those trees they’re going to roll and lockup in each other making it even more of a pain to try and clear.  yeah sure there’s some stuff out there that will climb this (rockcrawlers and tracks maybe) but even your average HMMWV isn’t going to get across this one easily.

One huge advantage of this obstacle is that it’s fairly easy to create.  Two guys that are good with chainsaws can probably lay this in within a half hour.  If they’re able to lay a tree on a dime (I ain’t that good but I’ve seen it done) then they can create an even more frustrating obstacle by interlocking the trees with the tops between the stumps on the opposite side of the trail.  This kind of obstacle is going to probably be more trouble than your average threat is willing to deal with especially if they showed up unprepared to deal with it.  The pic below illustrates a completely interlocking Abatis.  As stated notice the treetops (brown arrows) are down between the stumps (brown circles) of the trees on the opposite side of the road.

If those trees are still attached to their stumps then even a dozer is going to have some work ahead of it getting that clear.  Think about this – that’s only six trees.  If a group of dirtbags in a truck come up to this two miles from your homestead unless they are equipped with chainsaws (and fuel for them) and tackle or a dozer it’s going to be dismount time for them.

Of course the effectiveness of an Abatis is dependent on two things – it’s placement and complexity.  This is where we’re going to look at integrating obstacles.  Say we take that Abatis and place it in conjunction with a natural obstacle like a creek crossing the road with a dense tree line on either side.  By cutting that Abatis where the front edge of it is on a bridge we’ve created an obstacle that the threat is going to have to confront head on.  This is going to cost the threat even more time, effort, and resources to get through.

Look at your Area of Operations (AO)  and try to identify the possible natural obstacles that you can exploit using this kind of technique.  Bridges are a natural choice however ravines, cuts, and slopes also can lend to the effectiveness of an Abatis.

Exploiting that bridge is a simple choice however there’s even more that can be done.  This is where we enter obstacle complexity.  You don’t want to put a simple looking obstacle in the threats path.   Nope it’s always much better to give them something that looks like it’s going to take more effort than they are either able to or willing to deal with.  By taking the combined obstacle we’ve got (the Abatis and creek/bridge) we can further frustrate the threat by exploiting that bridge (a natural vehicular choke point) even further.  If you have the resources then you could possibly drop it into the creek however that is a likely permanent solution that may bite you in the backside later.   Another option is to block it with a vehicle hulk.  In the diagram below I’ve placed a pickup on the bridge directly in front of the Abatis – good and even better if the Abatis is actually tied into the truck on the bridge.  The best method to do this is drag it up there and park it crossways on the bridge so that it completely block the lanes.  At that point jack her up, pull the wheel and drop it on the axles.  Make sure you turn the wheels when you get it positioned so that if it shoved from the front it will steer itself into the obstacle sideways and not straighten itself out.  Would it be better to flip it on its side or roof?  That depends – the key point is you want as much of the vehicle that isn’t near smooth on the ground.  I’ve seen a single jeep pull a flipped truck off of a road.  Likewise if it’s on its side it may be drug easier.  Basic physics = the more ground contact the vehicle has the more resistance to movement.  I call this kind of obstacle a compounded obstacle.

Not only does the threat have to deal with that vehicle but there’s the Abatis immediately behind it which may be resting on it.  Which brings up another point – work your obstacles from the point of contact (where the threat is going to hit them) back towards your position when creating them.  Using this kind of obstacle the threat is going to need some serious resources to clear it if they want to keep going in vehicles.  I’m going to add one more pic here.  This is part of my obstacle plan for my AO.  The area it’s going into is a set of “twin bridges” on a blacktop road that leads out to my ranch – I’m the only folks down this particular road.  It’s not the only route to the ranch but is one that I don’t absolutely rely on.

Notice I’ve got two trucks blocking the bridges with an Abatis between them.  The first truck the threat encounters is going to have to be drug out of the way or forced into the creek.  In this case the guardrails are concrete pilings so it’s going to take some serious effort to do that.  Then there’s the issue of having to deal with that Abatis and the other truck after it.  I counted just under twenty trees that are going down when this gets dropped.  That’s a lot of timber to have to get out of the way.  The offroad terrain in this area is pretty soupy swamp and moccasin infested as well – even ATVs catch heck in it.  Now there’s one difference here.  Notice the red lined X’s?  That’s concertina (military razor) wire I’ve picked up at a Department of Defense Auction.  It’s going to get wound in all around (and under) those trucks and tied into the pilings and the Abatis itself.  Not only does that frustrate trying to get the truck and the Abatis out of the way but it does something else.  This is an example of a triple compounded obstacle using natural obstacles in conjunction with manmade and man-improved obstacles.  If the threat decides to dismount and proceed they’re going to have to get wet – twice.  And slog through some serious mud.  And after that it’s still two and a half kilometers to the homestead and some more surprise goodness.  Basically I want this far enough out that by the time they get there they ain’t going to be exactly fresh.  Like I’ve stated it won’t stop a dismounted threat but it will deter them and help wear their asses out.  Any chair in a fight.

Use your imagination when it comes to placing compounded obstacles.  These are some examples that hopefully will help you in the long run.  Now we’re going to get into the decision process part of this entry.  Before proceeding it’s been a while so I’m going to touch on the key truths of obstacles again.  These are:

  • Obstacles will not stop a threat.  They will delay it, but a determined threat is going to eventually breach an obstacle.
  • Obstacles that are covered by observation and fire are more effective at accomplishing their goals than unobserved ones.
  • Obstacles that are concealed typically frustrate the threat better than visible ones.
  • Placed correctly an obstacle can channel the threat into your field of fire.
  • Natural obstacles tend to be the most effective.  Man made the least.
  • It is much easier to halt or delay a vehicle than a person on foot with an obstacle.
  • Obstacles require periodic checking and maintenance to remain effective.
  • And finally the greatest truth of them all:  Any obstacle that’s going to delay a threat getting in is most likely going to delay YOU getting out.

Ask yourself some simple questions based on those truths before you decide to put these in.  Are you going to need to get across this is you have to shag out under pressure?  Will you be able to?  Is it going to slow you down so much that the threat can bear down on you while you’re in the middle of it?  Will it frustrate your shovel ready neighbors coming to your aid if you’re being hit?  Does someone else in the tribe need access across this area (it’s bad tribal juju to cut someone off from the rest of the tribe)  Before you drop a bridge think about possibly needing it later on.  In my case I’ve got other routes and this is a high speed avenue of approach for the threat so the advantages of blocking it are greater than any disadvantage.  But if things ever do get back to normal then there’s the possibility of clearing it and using that route again.  And if things get worse then I can increase the complexity even further by adding doings things like adding more wire, completely cutting the bridges, etc.  Bottom line:  Take those truths into account before you place any obstacle.  Would I place this kind of obstacle pre-SHTF?  Nope, I have a trigger point that determines when I’m going to do it.  That trigger point is a well trusted local LEO (and relative) that’s going to notify me when it gets bad enough the county LEOs quit coming in for shifts.  IMHO at that point without the rule of law the lawless will start their shit.

Posting is going to be light for the rest of this week – I’m taking a couple of days to go and see the new grandson so don’t expect another entry until probably late in the the weekend at the earliest.   Hang in there, read Mosby’s blog, and remember as CA sez: Tempis Fugit!

About Treaded

Semi-retired career and contract troop. I own and maintain my own small ranch out here in beautiful rural America.
This entry was posted in Defensive Measures, Hardening the Homestead, Security Planning, Terrain and AO Development. Bookmark the permalink.

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