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Old 06-04-2013, 05:22 PM   #1
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Question What is a average turn radius that would fit most small to medium trailers?

now i know this i impossible questions in a lot of ways.
but i am planning out a circular driveway and pondering what my turn radius is?
and since my driveway will probably outlive my particular set up, i was hoping to design it for a safe average without wasting a lot of space. we can assume that nothing else will be parked there while pulling the twinkie thru.

I also have been looking to figure out what the turn radius of the UPS truck and that is a surprisingly hard to find stat? any thoughts?
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Old 06-04-2013, 06:07 PM   #2
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I think the width of the drive would be more important than the radius because a longer trailer will swing to the inside farther than your 18', if that's what you're designing for.

In most cases, unless you are towing with something like a Smart Car, the trailer will follow the tow vehicle, and in any case, the longest rig will turn around on a standard city culdesac. (SP?) Street with a circle at the end of it.
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Old 06-04-2013, 06:40 PM   #3
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yeah in my town at last cup-de-sacs are 70' dia and that would be a huge driveway!!

i know i can can turn in waaay less than that at low speed, but figure the right thing is to make it as big as i can without wasting space. The drive in will certainly be around 20ft wide as i plan on having parking on one side rather than on the circle for most things.
For right now i dont think im going to a center island in the circle, it is going to double as a play field for my kids. so width and cutting corners should not be the issue.
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Old 06-05-2013, 05:20 AM   #4
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According to the National Park Service's "Park Road Standard" (http://www.wfl.fhwa.dot.gov/resource...k-road-std.pdf) page 17, the outside front wheel of the typical tow vehicle will trace a radius of 24 feet (48-foot circle), with the outside corner of the tow vehicle's front overhang tracing a radius of 25.8 feet. While turning, the trailer's rear inside wheel will trace a parabola, that at its closest approach to the center of your radius will only be about 5.5 feet.

You might want to download the document and take a look. I've used this document as a guide when designing paved roads— as part of my job— at some of the CoE New Orleans District's navigation locks.

Based on this guidance, you'd want the drive to be about 25 feet in outside radius, and the inside at about 5 feet radius, if you wanted to make sure all wheels were always on the pavement as you turn 180 degrees. But allow a few feet of open area on the outside of the curve to make sure your overhangs also have clearance.

Actual turning radius may vary depending on the exact geometry of your tow vehicle/trailer combo, but for planning purposes this should be reasonable close.
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Old 06-05-2013, 06:52 AM   #5
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Wow that is wonderfully helpful!

I also found another document that said one of the main truck company needed a 55ft diameter for its 30ft trucks that seem similar to the large ups trucks.

So I'm working on putting in a 56ft (56 because it happens to be surrounded by a hexagon and I need the sides to be in a certain multiple.)

So it looks like this should be a very safe turn radio us without too much waste.

I'm off to go read that document!
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Old 06-05-2013, 07:51 AM   #6
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what your forgetting...

And you will only forget it once. When you do those incredible tight turns (forward and backward) the aft corner of your tow vehicle becomes lethal. A pickup is probably the worst dent squisher of all, however, any rear bumper or fender will smash the front of your Airstream in a tight turn.
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Old 06-05-2013, 07:52 AM   #7
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Quote:
Originally Posted by Protagonist View Post
According to the National Park Service's "Park Road Standard" (http://www.wfl.fhwa.dot.gov/resource...k-road-std.pdf) page 17, the outside front wheel of the typical tow vehicle will trace a radius of 24 feet (48-foot circle), with the outside corner of the tow vehicle's front overhang tracing a radius of 25.8 feet. While turning, the trailer's rear inside wheel will trace a parabola, that at its closest approach to the center of your radius will only be about 5.5 feet.

You might want to download the document and take a look. I've used this document as a guide when designing paved roads— as part of my job— at some of the CoE New Orleans District's navigation locks.

Based on this guidance, you'd want the drive to be about 25 feet in outside radius, and the inside at about 5 feet radius, if you wanted to make sure all wheels were always on the pavement as you turn 180 degrees. But allow a few feet of open area on the outside of the curve to make sure your overhangs also have clearance.

Actual turning radius may vary depending on the exact geometry of your tow vehicle/trailer combo, but for planning purposes this should be reasonable close.
Now where else you gonna find the depth of knowledge and answers like this but on the AIRFORUMS! THANK YOU AIRFORUMS (and Protagonist!)
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Old 06-05-2013, 08:18 AM   #8
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Seriously! I have been looking for turn radius info for days, this is the first time I have seen info for anything in between a regular car and a 18 wheeler. And that's a pretty big gap!
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