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Turning radius for Truck & RV

Turning radius for Truck & RV

Turning radius for Truck & RV

We are finishing a driveway on the new property.  So I thought I would ask the "civil" forum for help.

The driveway goes straight back and then has a oval loop.  The loop is 100-125' high.  I found design info on Cul-de-Sac Designs.  Seems the 30' min radii so too small and the 40' radii with center island would work nicely.  I can actually go 50' on the inside.  Getting the 20' lanes down the sides and a wider, say 25', lane on the top is okay.

It is just the tree hugger in me that wants to keep the 40-50' inside radii.  I just don't know if it is enough for the future vehical designs.

The loop island looks so nice now and if I make the inside radii bigger I start taking down 12"+ dia trees that would be in the new back yard... that turns into a back "driveway".

RE: Turning radius for Truck & RV

You didn't ask a question.

There is a program available called Autoturn which contains numerous templates for many sizes and types of vehicles    ( including aircraft). The program is expensive but the plastic templates should be reasonably priced.  Do Google search on "autoturn".

Good luck

RE: Turning radius for Truck & RV

Your local DOT and or traffic engr. should be able to help. ASSHTO would want you to pay for this I think.

RE: Turning radius for Truck & RV

Is 27' inside radii large enough for a truck pulling RV?  The lead in/out lane can be 22' and the top of the oval is 36'.

RE: Turning radius for Truck & RV

Please ! go find a open area or parking lot and actually measure the minimum inside radius your vehicle combination is capable of.  No one on this forum can answer your questions with the information provided and without a scaled picture of what it is you're trying to do.

Good luck

RE: Turning radius for Truck & RV

Sorry to waste your time ...

I just don't have any way to measure some future vehicle.

RE: Turning radius for Truck & RV

Why not visit some RV parks in your area ?  Look around. Observe curve radii. Measure them.  Visit RV dealers and get specifications and brochures on RVs, including turining radii bot backwards and forwards.

RE: Turning radius for Truck & RV


AASHTO's "A Policy on Geometric Design of Highways and Streets" (known as "the green book") has a design vehicle called P/T which is a 19ft long passenger car with a 27 ft. camper trailer.  The turning template for this vehicle shows a 33 ft. min. outside wheel path. It appears one could have a center radius as small as 16 ft. (concentric with 33 ft. circle).

Wider paving does give more room to maneuver.  If one makes a inside radius larger than 16 ft., be sure to expand the outside radius (if one maintains 18 ft. min paving width, probably OK)

If one is envisioning a larger design vehicle, things change.  A tractor trailer (AASHTO WB-50) should be able to handle a circle with a 25' inside paving radius and 55' outside radius.

RE: Turning radius for Truck & RV

I took another glance at the green book.  If, you are considering a Motor Home, it adds another dimension.  It would require about a 42 ft. outside radius and approx. 25ft. inside.  A Motor Home with trailer wouldn't be too different from the tractor trailer - could perhaps tolerate 30' inside radius instead of 25'.

RE: Turning radius for Truck & RV

Thanks TerryScan!  That is great news.

The 33' (or 27') inside radius would work then.

I have 18-20' wide lanes at sides of oval and a 36' high lane at top.  So they would also work.

I am so glad I don't have to take down another 18 8-14" trees plus all the little stuff.

RE: Turning radius for Truck & RV

Thanks again TerryScan!

We have worked hard on this 700' driveway with loop.  I was hoping that we were getting it to where we could stop cutting down trees.  And start putting down the initial base layers.

RE: Turning radius for Truck & RV

Your welcome.  I would also consider the all the other advice already given, especially checking local RV dealers to get info on possible models you may purchase.

RE: Turning radius for Truck & RV


Some vehicles have different turning radii depending upon which direction they are turning, right or left.  It might be just due to the steering mechanism, or it might be designed in on purpose, depending upon the use of the vehicle.

Also, turning radii can change on a given vehicle when wheelbase changes.  So, a given model truck delivering concrete can change when used as a dumpster hauler, just to cite an example.

Check your variables, and design for the worst case.


RE: Turning radius for Truck & RV

Thanks!  I will keep in mind the variables.  We might have to test drive (in the driveway) before we buy.

We will know how a semi does when they come for the oaks, cherry, and walnut to mill up.  We have to get around and skid drag them to crane on semi.  They may also be able to give some advise; before we lay the limestone and slag.

I would not look forward to moving the stone if we have problems.  But moving a garage or house would be much worse; so will make sure to test drive before the first foundation is finalized.

RE: Turning radius for Truck & RV

I would once again thank everyone that posted to this.

We had a damaging storm come thru.  So, turn-around and driveway is natually wider.  Uprooted trees (7) and blow-down (cut 18-6"+).  We worked with two saws for four hours in three acres alone. Other 10 acres will just have to wait.

RE: Turning radius for Truck & RV

Depending upon the local regulations, the length of the driveway, width, its use (private or public, one owner, or shared by two or more homeowners), etc., might require a turning radius or a hammerhead turnaround large enough to accommodate a fire engine/ladder truck.  Check with your local regulating agencies before you design and build.

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