Fence reinforcement to stop a vehicle

I have a fairly standard 6 ft privacy fence. Pressure treated 4X4s subk in concrete every 8 ft with 1x6 cedar planks hung on 2x4s attached between posts with metal brackets. Obviously not something that would stop any kind of vehicle.
For the parts that run along a road I would like to add some simple and cost effective and preferably attractive reinforcement to the fence to repel a car or truck from crashing through...either by accident or on purpose.

I am thinking of running a 1/2 inch steel cable the full length of the fence and attaching it to each post through a heavy eyelet or such. If this is ran at about 24 inches off the ground it seems this might work reasonably well. I will need to reinforce the posts at the ends that hold the tension and a couple more in the middle.

Anyone try this and have any suggestions on how to make this most effective while keeping it decent looking and reasonably priced?
What is inside the fence? To make it look attractive a line of RR ties would give a good border, just drill through and drive rebar through holes and into ground. when the vehicle hits them it should stop or at least drastically slow it to avoid hitting house. The cable you mentioned would only be as strong as the posts it is attached to.
i find my self thinking of these things often. The cable is a decent idea, the two end attachment points would have to be pretty strong and heavy, but I could see this leading to a domino effect with your post if the car was going fast enough. I wouldnt connect it to the posts, but have it tight between the two end points which would be concrete and be very heavy, should be underground a few feet too. Rocks stop vehicles well, and they look nice in a bed with bark around them, stagger big rocks around the fence every few feet. Can you do anything on the other side of your fence? A steep and deep ditch will stop all vehicles unless they have tracks. When you do reinforce it post some pics
"Gravity blocks" in a raised bed with dirt in-fill and some landscaping/food plants. It depends on whether your extra space is inside or outside the fence, whether it gets sun, if you have the ability to make major changes to the slop of the yard etc.

A moat doesn't necessarily have to be filled with water. A nice sharp drop will stop most vehicles, especially of there were a backstop. Look at the way federal building all have big heavy concrete planters outside the entrance now. Those are not for decoration. You could probably build a form and cast them yourself on site pretty cheaply.

Mark W.

Come down to south of Wilsonville on I 5 and take a good look at how the state put up the vehicle barrier in the meridian. Granted theirs is OVER kill designed to stop a truck or 80mph pickup. But it would give you a good idea what yours would need to stop a drunk in a SUV.

A row of railroad ties along the inside of your fence would add a lot of resistance to a car passing through. A lot would depend on the grade of your yard along the fence.
I used to live in a semi-rural house on a curve in the road. People used to smack my mailbox post down fairly regularly. I always thought it tempting to replace it with a half-buried railroad tie. Probably a good thing I didn't.

OTOH, I've been driving past a home on the way to work for <cough> years that sits on a curve in the road. Watched the tree in the guy's yard collect scars over the years until it finally died. Guy replaced it with a section of sewer pipe (?) turned up. Section is about 5-ft long (tall) by about 6-ft in diameter. Concrete. Filled it with dirt and planted a new tree in it. I imagine it'd stop most anything short of a locomotive. Does cost a fraction of his yard, but keeps the uninvited out of his bedroom.

Google 'decorative bollards'.
You will probably find a ton of options for bollards that could go outside or inside the fence, or even replace it if you wish.
I like the decorative rock idea. I think they look great and intimidating at the same time. But a good bollard would be handy. You can get the style that locks to a sleeve/anchor that is imbedded in the ground. That way if you ever have the need to get a vehicle or equipment into your yard you can always easily unlock and lift the bollards out of the ground. And they can be had in countless styles/finishes.
Those are all great ideas.... I am particularly fond of the tank barriers and dragons teeth etc. HAHAAA! Getting some rock would work but I am looking for something inexpensive. I love the simplicity of a ditch but outside the fence there is not much distance to the road and a ditch inside would eat up too much yard space. My wife thinks I am paranoid as it is so anything too expensive or elaborate will be squashed.

We have decided on simply 3 steel pipes filled with and buried in concrete with at least one.... maybe two..... runs of 1/2 inch SS cable running the length of the fence. I just got a great price on some used cable on Craigslist.
A couple different options. Since you are in the OC I, you could either be rural or suburb.

I used to live in rural OC and we always had a problem with people running over our mailbox. Finally I took an old coil spring from a 1 ton truck and welded a 2" hollow tubing to it and mounted the mailbox on that. Then I welded a 1ft piece of the tubing to the bottom and then sunk that in concrete in the ground. Needless to say it worked perfectly and the next time the mailbox got ran over that bar and spring just bent over then slammed back up underneath the truck. Killing the oil pan and transmission. The truck was about 100 yards down the road the next morning. The police enjoyed that one.

Another house I had was out on barnards rd between canby and molalla. I took some concrete and made a form for some barriers kind of like this concrete divider obj free
Then I planted some arborvitae in front of it, then it was hidden from the road so the "curb appeal" was still good but then protected my house from some drunk, or dumb sh!t driving too fast on that road. Luckily that one never saw any action.
A friend of mine used to live where the mailbox took a REAL beating on a regular basis. Baseball bats to the box while driving for distance was a favorite Saturday night after the HS Football or Basket ball games.

SO...after replacing the box, post or both for the umpteenth time...we got SERIOUS.

Started with a 24" earth auger on the tractor and bored a 6 foot deep hole in the edge of the yard, right where the mailbox needed to be. We then talked the railroad out of a 10-footish section of 120# mainline rail and found an 8"x10"x9ft 1/2 wall steel rectangular tube and a section of 1" steel plate about the size of the largest package box the USPS stocked as well as the next largest one that fit comfortably IN the first one...then we ordered up a batch truck.

Poured the 24" dia hole full of concrete, used the tractor bucket to settle the rail in the center, then the tube outside it...which was filled with concrete also (about now the concrete guys were taking Polaroids of the process) and the prepared steel plate - holes drilled to accept 5/16 bolts that matched the reinforced bottom rail of the USPS box- set on top and zipped up with the welder. then we took the largest box and laid it on its back and put a few feet of concrete in it, sunk the smaller box in the middle and used a few 2x2s to keep it there and filled the rest of the space between the boxes with MORE concrete. The concrete guys now have taken about 35 polaroids.. After the mix in the mail box was set up, we used the tractor again to set it on the plate and bolt it on. Put on new numbers, painted the tube to look like wood to the casual observer and went in to have a few WELL deserved beers.

Fast forward a few weeks to the next home game.

At about 11:40PM my buddy hears a lot of drunken giggling out by the road...we were on the patio watching the coals burn down to ash and the beers empty...then the squealing of tires and an aluminum sounding WHACK-SMACK-tinkle-tinkle and a cry of suprise and a howl of pain and the sound of a vehicle leaving rapidly. We were just getting the last of the beans and steaks down when we THEN hear the sound of more serious sounding voices and the rumble of a heavy engine. That was followed by the revving of same engine and tires spinning in gravel. Then a RESOUNDING crashing crunching noise...and the sound of a radiator venting and things breaking. Then another vehicle speeding away.

When we took the tractor down to investigate we found an F-250 well wrapped around the post with the mailbox in the middle of the hood, still attached to the post. The paint was scraped and messed with and the box door was a bit bent..but it didnt move.

We called the sheriff, who took lots of photos and had the truck towed. Later found out that the kid with the aluminum bat had broken both wrists and the bat smacked back on the side of the mini-van and bent the slider door as well as breaking both the door window AND the back glass. So another kid went and got his Dad's F-250 4x4 with the heavy bumper and wanted to push the box over or break the post off. He was in a heap of trouble..as was the mini-van driver.

That one has lasted about 20 years now, with the one occasion replacement of the box due to M-500s put inside of it. We welded up a new shell out of 3/8 plate, sunk a smaller box in it and went back to work.
Come down to south of Wilsonville on I 5 and take a good look at how the state put up the vehicle barrier in the meridian. Granted theirs is OVER kill designed to stop a truck or 80mph pickup. But it would give you a good idea what yours would need to stop a drunk in a SUV.

A row of railroad ties along the inside of your fence would add a lot of resistance to a car passing through. A lot would depend on the grade of your yard along the fence.
this is along the lines of what i was thinking when the op brought up cable.

i'd try to find some 4 or 5 inch steel I-beam.. dig and pour deep footings, and run some quality high-tension cable through them. pour anchor footings at the ends and install tensioners. this way you could run the cable behind the fence, through the existing posts... those PT/cedar posts, even combined via cable, wouldn't be strong enough to stop a mid-sized sedan doing anything more than 20mph.

this would be expensive and labor intensive, but less so on both counts than anything else i've seen suggested so far out of those that would actually work.


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