What would be a minimum turning radius for a tractor pulling a trailer, such as a big-load-of-hay trailer? I’m designing my barn and site plan and a lot of people have recommended having a nice turnaround area for ease of deliveries, service trucks, etc.
We have about an 80ft space in front of the barn, which allows us to turn the semi tractor and a 53ft trailer. Makes for a good Long-Lining area too!
Much will depend on the type of tractor, where the wheels are under it, and skill of driver.
Get a good SOLID base that will HOLD up that tractor because they are HEAVY on every wheel. So dirt base needs to be layered, and deep, to take the weight.
Also have a driveway constructed so it can ALSO take weight, TONNAGE, without turning to mush when driven on in EVERY season, wet or dry.
This same WONDERFUL turnaround and driveway, will need to be up to the weight of Fire Trucks, fully loaded. I understand that can be 100,000 pounds or more. So the WIDE, solid, STRAIGHT driveway is actually an investment in hay delivery ease, protection of the barn with Emergency vehicles being able to get in there.
Good driveways are not cheap, take some upkeep, but WONDERFUL being able to use them in all seasons, for any size truck, never getting bogged down.
If you need a pavement that is designed to support a tractor-trailer (or even a fire engine) but want grass also use these type of pavestone (or similar product)
http://www.pavestone.com/conlock-ii-6-open-cell/
We have used this product for overruns on airport runways that have had aircraft run onto them without damage
While not recommended for preserving pristine footing, my hay guy has delivered full loads of 150 small square bales (~ 50#/bale) by pulling the loaded wagon w/ his 1/2 ton truck through my indoor - so his radius is within the 60’ width.
I’ve also allowed a neighbor to store fully-loaded haywagons in the indoor & he pulls those loads with a tractor.
Both come in through the rear sliding door to the indoor - 12’WX16’H
While not recommended for preserving pristine footing, my hay guy has delivered full loads of 150 small square bales (~ 50#/bale) by pulling the loaded wagon w/his 1/2 ton truck through my indoor - so his radius is within the 60’ width.
I’ve also allowed a neighbor to store fully-loaded haywagons in the indoor & he pulls those loads with a tractor.
Both come in through the rear sliding door to the indoor - 12’WX16’H
[QUOTE=clanter;7570133]
If you need a pavement that is designed to support a tractor-trailer (or even a fire engine) but want grass also use these type of pavestone (or similar product)
http://www.pavestone.com/conlock-ii-6-open-cell/
We have used this product for overruns on airport runways that have had aircraft run onto them without damage
http://www.pavestone.com/grasstone-ii/[/QUOTE]
These look awesome! I wonder about getting a quote… I want this on our future farm. I suppose you can graze over it, no worries about slipping or a foot doing into a hole?
This looks like a good reference http://onlinemanuals.txdot.gov/txdotmanuals/rdw/minimum_designs_truck_bus_turns.htm
[QUOTE=2DogsFarm;7570137]
While not recommended for preserving pristine footing, my hay guy has delivered full loads of 150 small square bales (~ 50#/bale) by pulling the loaded wagon w/his 1/2 ton truck through my indoor - so his radius is within the 60’ width.
I’ve also allowed a neighbor to store fully-loaded haywagons in the indoor & he pulls those loads with a tractor.
Both come in through the rear sliding door to the indoor - 12’WX16’H[/QUOTE]
A half ton and a hay wagon is not really a great comparison to a tractor trailer. 
OP, I get tractor trailers through my farm all the time. Most appreciated is a shallow loop. The “top” of my half-circle drive is maybe 100’ from the entry points. I grabbed a screenshot: https://scontent-b-lga.xx.fbcdn.net/hphotos-frc3/t1.0-9/10302634_10154149632245215_639772391031255587_n.jpg
Essentially, they just have to take a slightly curved path off the road, then pull right back on. There’s enough room to get two of them side by side there, or allow us full access to one side with the front end loader to get pallets off.
There is unfortunately enough of a grade that the big air-ride horse trailers cannot get in without bottoming out, so we have to load on the road, but any normal trailer is fine.
That’s the ideal, as far as ease of entry and exit goes.
If you want them to be able to back the trailer in somewhere, make sure that they can pretty much get the rig straightened out before backing in. They do not respond quite as well to minute adjustments, the way a horse trailer does, so you want to make it as straightforward as possible. 
In the picture above, we occasionally (for whatever crazy reason) get a driver trying to come “down”. It’s always a pain to get them back out, because even just that slight wiggle between the buildings takes forever to back someone through.
This may be more than you need but it’s informative:
http://onlinemanuals.txdot.gov/txdotmanuals/rdw/minimum_designs_truck_bus_turns.htm
G.
[QUOTE=PeteyPie;7569680]
What would be a minimum turning radius for a tractor pulling a trailer, such as a big-load-of-hay trailer? I’m designing my barn and site plan and a lot of people have recommended having a nice turnaround area for ease of deliveries, service trucks, etc.[/QUOTE]
In engineering we always tie in a circle with a 100’ diameter to handle the standard trailers (48’). Their turning radius is about 42’ but we play it safe and use a slightly larger area. We do have a program where we pick the size of the truck and run a simulation to make sure a tractor trailer can fit. But I’d go with a 100’ circle. 
[QUOTE=GoForAGallop;7570312]
A half ton and a hay wagon is not really a great comparison to a tractor trailer. [/QUOTE]
My Bad?
I read the original question as a tractor hauling a haywagon, not a semi-type tractor trailer.
Depending on the bales, I can haul a ton and half of hay in my 2H horse trailer. I think they were talking about a BIG load of hay.
Also big, our very own Tamara http://www.productionacres.com/hay%20005.jpg.
I remember, after I had given up my horse, that my dad allowed one of his employees to park a small semi load of gorgeous Oregon alfalfa on the turnaround in our driveway. (big turnaround) That pile of hay was the size of a small two story house - and I was pretty irked at Dad as the whole time I’d had the horse we were dragging home bales two and three at a time in the family wagon, and here we’d had the room for a full load the whole time.
If you don’t have room for a turn around, at least make sure your roads are wide enough with gentle turns and enough overhead clearance (tree branches no lower than 13’6"). Semi drivers are typically very, very good at backing up, and can often just back into the unloading area.
Our farm tagged grain-hauling semi usually weighs 80,000lbs (but we’ve had it at 125,000 once or twice due to inexperienced grain cart drivers). Your roads and turn around area need to support that amount of weight. And don’t just assume because it is paved that it can handle a semi - I’ve seen lots of paved driveways get destroyed by the weight of a loaded truck + trailer. They cave in, crack, and then just fall apart over time - the semi doesn’t get stuck, but your road falls apart.
These answers are so helpful! Thank you, everyone! This is exactly the info I needed.
I’m going to leave most of the driveway, actually, all of the drive which will be accessible to a big truck, unpaved and just have the house’s parking pad and short driveway paved. The property has a lot of granite bedrock and decomposed granite, so it should be fine for supporting the truck. Of course, that presents problems in other areas but that’s another thread…
I am putting a turnaround in front of the house and also a driveway circling the hay storage shed, so I needed to know the turning radius so that I position the shed far enough from the pasture fence to be able to easily circle the shed after unloading. That Roadway Design Manual (thanks ReSomething and Guilherme) was especially helpful because it indicates inside and outside turning radii.
I have to admit, when I was envisioning a BIG load of hay, I wasn’t thinking of a double load like The Jenners example, but the design manual has specs for those too. I figure that even if I never order that much hay, it’s easy to design for it ahead of time, just in case.
Now I need to make sure that the ups and downs are properly designed to avoid bottoming out. I have elevation changes along the proposed driveway so I’m going to have to think about that – thanks for that thought, GoForAGallop.
moving to dc:
…tree branches no lower than 13’6"…
…Semi drivers are typically very, very good at backing up, and can often just back into the unloading area.
No trees are along the proposed driveway, although I will be planting some and will take that into account.
I might use that idea (of backing up) to limit myself to one main turnaround in front of the house with the idea of backing in to the hay shed area.
