An Examination of the Roundabout

at Lumpkin Campground/A C Smith Road Intersection in Forsyth County Ga.

How NOT to build a Highway Roundabout! 

Revised 2/8/2012

By Joe Mehaffey

{  note:  This document can be downloaded or viewed directly from:  }

I have always been a fan of roundabouts at moderate and even heavy traffic road intersections.  I live on A C Smith Road and you can guess my interest when it was announced that we would have this improvement installed at an intersection nearby.  I have lived in the UK and have studied the design and guidance techniques in UK roundabouts during my time there. Some of the current roundabout design's most prominent design flaws are shown below in Figure 1.

Previously,  I have worked to develop community awareness that our new North Fulton Roundabout was not designed the way it should have been.  I submitted my comments and ideas to the Forsyth County Engineering department and they basically told me a) the roundabout design was fine,  b) It met all required design specifications and c) they were not going to make any changes.    Since I am NOT a Roundabout Engineer, but rather just a "Fan of Roundabouts" who knows a bad design when I see one,  there was no way for me to personally get to the crux of the matter.  I then decided to hire (at my own personal expense),  a very well known Roundabout Design Expert to read my comments/suggestions and also the rebuttal by Pond Engineers (the designers of the existing roundabout) and give me his design analysis.  After reading all these comments,  Mr Ritchie was to consider the existing roundabout topographical design and make whatever comments and recommendations he felt were appropriate and justified without input from me.  He has done this work.

Mr. Scott Ritchie PE is the President of Roundabouts and Traffic Engineering, Inc., and his headquarters is in Arizona.  See:  for details.  Mr. Ritchie has designed over 300 roundabouts and teaches roundabout design and acts as designer/consultant to various state,  county, and municipal departments and engineers throughout the USA. 
Mr. Ritchie's Resume can be found by CLICKING HERE.  For any engineers interested,  their upcoming Roundabout Design Seminars are described at  Mr Ritchie has linked a number of very interesting lectures and seminar talks within his Design Review discussion presented below.  Engineers will find these "How to Design Roundabouts" seminars and discussions very enlightening.  Just click on the links in the design review text as you come to them.

So what did Mr. Scott Ritchie say about the design of our roundabout?   He says that our roundabout design needs rework, and he goes into some of the design problems in modest detail.  I have to say that he did not like some of my proposed fixes, specifically, cutting back the center truck overrun area,  but then  I accept Mr. Ritchie's conclusions and Expert Opinion which  Design Review is found HERE.  I think Mr. Ritchie's comments are very appropriate to our situation.  One point I will emphasize here.  I agree fully with Mr. Ritchie's statement that (in essence) HAD THE CURRENT DESIGN BEEN SUBJECTED TO A PEER REVIEW BY ENGINEERS EXPERT IN ROUNDABOUT DESIGN, THEN THE PROBLEMS IN OUR ROUNDABOUT DESIGN WOULD HAVE BEEN CAUGHT AT AN EARLY DESIGN REVIEW. 

I find it extremely interesting that Pond Engineers themselves show us a good example of what OUR  roundabout SHOULD look like in the following photo! 

This image came from the Pond Transportation website.  It is the ONLY roundabout photo that I saw there.  It supposedly shows OUR North Forsyth Roundabout!  However, notice that this is our site BUT, it is apparently Pond's original very preliminary design without the addition of the sidewalks we actually have around the perimeter of the roundabout.  Note especially the wider spacing between the Jot-em-down entrance over to the Lumpkin Campground exit.  This roundabout design  generally looks good to me and likely had this been the design that was ACTUALLY BUILT,  but perhaps somewhat reduced in diameter,  we would not have the problems we do now!  How did the design change to the very much smaller roundabout get approved?  Who authorized it?  Why?  Does anyone have an answer?

Photo 1.

Figure 1 below.

Figure 1.  Current North Forsyth Roundabout Design Topo

Above is the Roundabout Design ACTUALLY BUILT at the North Forsyth site.  The diameter is about 87ft on the actual roundabout.  It should have been more than 120ft for this "coffee can" style roundabout on a 50mph highway.  The small diameter makes the design speed for the roundabout about 13mph which is far below standards for the 50mph highway on which the roundabout is placed.  The right turning angle exceeds 90 degrees for the westbound to northbound turn which makes this turn unusually slow which is a safety hazard.    The entrance islands do not properly direct traffic into the roundabout and this can be a safety hazard.  Cars can "barrel through" from the NE leg to the West leg without even slowing down which is a safety hazard!  Overall, this cramped design with unsymmetrical traffic guidance and control is not what we should have gotten for our money!

With this revision of my review information on the North Forsyth Roundabout,  I believe I have made my points which are:

1) The existing North Forsyth Roundabout is far from an  optimum design.  It is too tight and too small in diameter and the geometry is not optimized.
2) As presently implemented, there are a number of unresolved safety issues.   These include the fact that it is possible drive from the Jot-em-Down entrance westbound to the A C Smith Road Exit at 50mph! 
3) My most important point is that NEVER AGAIN should a roundabout be built in the county without a detailed PEER REVIEW by a ROUNDABOUT DESIGN EXPERT.  I note here that Pond Engineering list MANY capabilities on their capabilities list. ROUNDABOUTS are not even ON this list.   Complete dependence on engineers operating outside their area of expertise can result in problems as in this case.  In fact, anytime an expensive project operates without PEER REVIEW of designs,  the customer runs the risk of problems.  The Georgia DOT offers a FREE design review service though I am not certain as to the expertise on roundabouts available at GDOT as we do not have many roundabouts in Georgia as yet.  In any case, the GDOT was not called in to review the design of OUR North Forsyth Roundabout. 

Other References:  Click Links below...
Comparison of North Forsyth Roundabout against the USDOT Roundabout Guide
Pond Engineering's Rebuttal to my above comparison  Note that Pond a) did not directly address my questions and b) maintained that their design either MET or did not need to meet ANY of the referenced guidelines including putting a MINI URBAN roundabout on a RURAL 50mph highway.  Their answers were from the standpoint of their MINI URBAN ROUNDABOUT design which was NOT the size and design of roundabout suitable for our North Forsyth Intersection.  Most of us can recognize that a 50mph Rural Road is definitely NOT an URBAN setting!   Even if the design team were not REQUIRED to follow the referenced roundabout guidelines,  their actual roundabout design proves that ignoring the USDOT guide's many years of wisdom on roundabout design may not be wise.

YOU can help get the message to our Forsyth Engineering Manager and to your County Commissioner.  This, hopefully, will prevent this kind of major design error from happening in FUTURE Forsyth County Roundabout designs.  Tell them you do not like the county building this undersized roundabout when there is a GREAT example of a properly designed roundabout just a few miles away at Lumpkin Campground and Dawson Forest Road.  Ask what they can do to improve the existing one. 

Names and addresses of Forsyth County Government people involved who you can call or eMail and leave your message are as follows:

County Engineering Manager

Mr. John Cunard

770.781.2165 Phone

Our North Forsyth Commissioner

Mr. Richard Bell

Phone: 678.513.5884

Mr. Brian Tam


Phone: 678.513.5882

Mr. Pete Amos


Phone: 678.513.5881

Mr. Todd Levent


Phone: 678.513.5883

Mr. Jim Boff


Phone: 678.513.5885

Please note.  If you are reading this on a printed page, please go to for the webpage so you can view the many links listed in the text.