I have a brick planter attached to my house between the driveway and entry stair, about 9.5’ long by 2.5’ wide by 1.5’ deep (at the deepest end, the area has a slight slope to it). The corner by the driveway is curved rather than square. Since this is San Francisco, the planter is only about 8’ in from the sidewalk (lots are small here). Closer to the sidewalk there is a basin cut out of the concrete with a 3-year old tree in it; the bricks around that basin also show signs of having been hit by cars from time to time, fortunately no damage to the tree.
This is a narrow street and people frequently use driveways to turn around. Our driveway seems to be a favorite due to its configuration (long description, probably not relevant). A couple of weeks ago, someone (unknown) rammed into my planter to the extent that the curved corner is broken completely free and is loose; there is also a top to bottom elongated crack further towards the stair that is not loose.
I suspect its beyond repair and will have to be rebuilt by a professional.
I am considering putting a concrete bollard near (but not too close to) the driveway, between the planter and the sidewalk, with the aim of protecting the planter and the tree from car damage. This is something I think I can do myself. This is what I have thought of so far:
Locate site for bollard.
Get 811 to survey for underground pipes and lines.
Rent small jackhammer to break through existing concrete.
Remove concrete, dig down maybe one foot.
Place concrete form tube(1) in the hole, make sure it’s plumb.
Pound maybe 5 rebars into the ground inside the form tube. Cut off at the top of the tube if necessary.
Mix concrete and fill tube, wait for it to cure.
Remove tube(2)
Apply additional concrete to the top to round it off.
(1) the smallest I can find is 8", I was hoping for something like 6" but I guess this will do.
(2) do these things just slide off, what prep to make sure that happens?
Don’t recall how the tube forms come off, but have you considered PVC pipe for the form and just leave it in place? Glue a cap on top and maybe paint it an attractive color?
Digging down only a foot probably isn’t going to cut it. And the rebar pounded down into the soil won’t add much.
I deal with vehicle bollards a lot. You generally have two approaches: significant mass or deep anchorage. In most cases, I would suggest installing steel pipe to a significant depth and filling it with concrete. Of course, you also anchor the pipe in concrete. Two or three pipes would be even better. You can even disguise them with a nice planter or two placed over them. (Use a cheap planter, as it will be totally destroyed.)
A thought - if you’re going to have a professional repair the other damage, why not get a quote to have them do the bollard at the same time? It might not cost much and you’ll get it all done at once.
In the meantime, you could do what Caltrans does. A trash can filled with water or sand (or both). Sorry that people are such assholes.
You can actually go to several sites that will provide details on what the US government says about stopping vehicles, but I’m going to stick with “a DIY guy wants to stop slow-moving passenger vehicles from driving into his yard” stuff.
You probably only need about 30" of bollard extending above-grade. That will hit most passenger vehicle bumpers. Remember, the bollard will be like a lever…when a vehicle strikes it, even at slow speed, there will be a lot of pressure on the portion that extends below-grade.
I’d cut a section of concrete (use a concrete saw or hire a concrete cutting service to get a nice, even rectangle) and use a post-hole digger to go down at least 4’. Deeper is better.
Use at least a 4" pipe, or as big as you feel you can handle. Put concrete in the hole (either pre-mixed or out of bag and add water) so you have at least 3-4" of concrete on all sides of the pipe. Insert pipe and prop up straight. Fill pipe with concrete and round off at top.
Backfill hole and refill concrete section you cut out. (I’m not going to bother explaining how to do joints, but make sure you leave space for backing rod, sealer, etc.) Prime and paint pipe. If you like, get a redwood planter or something and cut a hole in the bottom so you can slip it over the pipe.
TL;DR: Get at least 4’ in the ground. Filling the pipe with concrete will keep it from bending if it is struck. Be prepared to rent a tow truck if you ever want to take it out.
I’d aim for at least 2 feet into the ground. 36" is a good hieght. Taller means people will see it before hitting it. I’m a fan of steel pipe for them.
When we do commercial wells I usually put 4 bollards around them. Having a drill rig on site makes it really easy. Normally we use half a piece of steel well casing for each so it’s 6-7 feet below ground. Only direction they’ll ever move is straight up if we need them out for some reason.
Here’s one set of plans, with an article explaining how the design was reached. It’s to keep cars from hitting a furnace, so it’s probably a little overdesigned (3 ft above ground, three ft below ground, 18 inch square foundation, and 6 inch pipe filled with concrete).
I’d advise painting it bright yellow or the cars that hit it will claim that they couldn’t see it and that it was therefore a hazard. Reflective tape would also not be a bad idea.
I’ve seen 2 ft bollards with 1 ft deep foundations - - on their sides. When they’re hit they just go over.
Since you’re installing it in the sidewalk, the sidewalk will add support and you can use a shallower foundation.
Thanks for the diagram. The bollard will not be in the sidewalk, it will be on my property in an area that is mostly concrete about 3 inches thick, and about four feet in from the sidewalk. I don’t think anyone who hits it will have any legal claim against me, but I was planning on painting it some visible color. I’m also going to check with the city to see if there are any permit issues.
Why not consider steel bollard? It will be thinner and engineered for the purpose. Most of them require embedding rather than surface mount installation, but still likely simpler and more reliable to do than forming a concrete bollard.
I did not see “obtain a city permit” on your list of things to do. Do not assume you can build this, even within the footprint of the old planter, without approval. Rest assured the guy who crunches his car on your unpermitted bollard will check. And then you might be paying to a) repair a damaged car and b) remove an illegal bollard.
You know, I really like this idea. I’m going to give it serious consideration (like where I would find a rock, and how would I transport it, and things like that).
Rockeries are a thing. I know there was one in the Santa Cruz area, but I’m sure there are some much closer to you. Big old rock is great idea. Maybe 2 even. With luck, you can even get it delivered and placed.
I find it difficult to believe that buying and having delivered a very large landscaping feature in the vicinity of a public road can avoid the question of permitting just because the landscape feature happens to be a rock.
You’re having it installed. Depending on the strictness of the local permitting regime, I could imagine any substantial installation would call for the whole nine yards of paperwork and inspections.
Make sure you’re legally OK for stuff like setbacks from the road, too.
Get yourself a large photograph of an adorable little girl. Put it onto a sign, like the ones picketers carry around. Pound the sign into the ground next to the tree. Tie a bunch of mylar baloons to the sign (let most of the helium out). Surround the sign, the planter and the tree with stuffed animals and dollies. If the adorable moppet looks Catholic, include a few of those religious-looking candles in the [del]shrine[/del] display.