How to Stop Cars From Turning Around in Your Driveway
People making u-turns in my driveway
My home is on a fairly busy street and lately I've had people actually using my circular driveway to make u-turns.
It wouldn't be so bad... except to say my driveway goes around my house not in front of it.
Is there anything I can do... short of installing a fence... to keep these intruders out???
Well, maybe ...
1) A sign that says:
"Private drive, KEEP OUT"
2) A sprinkler system on a sensor (and timer) that comes on when a car enters the drive. The sprinkler would be "ahead" of the vehicle entering. That would stop them from going forward any further - to avoid getting wet.
3) A sign that says:
"Beware of Bad Dog. Enter at your own risk"
For some reason, this didn't get posted ...
My driveway use to be used a lot for that. Consider parking your car down there and walking to the house. Obviously, this may create 'logistic problems' for you but that's my idea.
I had one neighbor that did it all the time. I knew them and did tell them one time not to do it since I have to 'maintain' the driveway. NOT that I was looking for them to pay me because I really didn't want them to use it. Since they didn't stop, I blocked it. (They've since moved ...)
IF I had to, I could park my car in front of the house and my wife could do the same, whereas one of us would use the 'spot' in front of the driveway as a parking spot. Perhaps you could simply 'obstruct' your driveway entrance juuuuust enough to make people take a 2nd thought about using your driveway as a turn-about. Of course, if they 'hit' you, will you or ANYONE see them do it?
Maybe during the day, you could totally obstruct it. And at night, just forget about it. I wouldn't advise putting a 'nail strip' or anything across it because you would lose in a court case. You see, in laying the strip down, you're intentionally trying to 'cause harm' to someone unexpectedly. I don't know if you could, legally, get away with putting up a sign AND laying a tack strip! Who knows.
Ya have a tough situation. My best to ya and hope this helps.
How about this.... In big letters and official looking.
OFFICER TRAINING/UNOTHERIZED VEHICLES
IMPOUNDED/DRUG ENFORCMENT
OFFICER ON DUTY!!!
you know what I mean. Ge the message across that there is some kind of official thing going on here. Do not say that you are LAW officials, but mix the words so that they think if they use the drive, they might suffer a big fine or confiscation..... 
Hey, here's one more....
How about a sign that says:
"Sleeping Baby. Please don't drive through."
I'll bet you'd be surprised how many people will be more considerate then.
Place a "NO TRESPASSING" sign at your driveway entrance. Then block the driveway on the backside of the house so that once they are committed they are stuck there and have to back out, they won't chance getting stuck again. Also if you are home they are caught in the act you can warn them of the consequences of private property trespassing.
You may have found a solution to your problem by now, but I thought I'd give my input anyway.
I knew a lady who had a large chain across her driveway and she had what looked like a garage door opener that would drop the chain down - she would drive over it, and then the chain would pull back up again. I'm not sure where you could get a device like this because I saw this about 20 years ago - but they exist!!
I suppose you could put up a chain with a no trespassing sign that you unhooked each time you drove in...but that might be a hassle!
Sit on your stoop for a few days with a 12 ga shotgun and a case of beer. Works for me.
:-)
Or post signs and scatter tire jacks/stop sticks.
You can put up a sign that says no tesspassing and then get a tag number of everyone that does it or check to see if you would be held acountable if not i would lay down some tire spikes. 
I have used a product called Drivewayspikes.
No more idiots.
BV005519
11:56AM | 08/31/14
I found A simple device.
WWW.DRIVEWAYSPIKES.COM.
BV008271
08:54AM | 07/06/15
Simple. Put one of those "kids at play" signs (like this one: http://www.amazon.com/Step2-KidAlert-Pup-V-W-B-Playset/dp/B00QZ2PJAI/ref=sr_1_1?ie=UTF8&qid=1436187231&sr=8-1&keywords=kids+at+play) in the middle of driveway...
BV015596
05:52PM | 01/28/18
My uncle had this problem up in Prescott Arizona he put a big log in front of his driveway at night time. one night, boom, a car hit it.
How to Stop Cars From Turning Around in Your Driveway
Source: https://www.bobvila.com/posts/22261-people-making-u-turns-in-my-driveway