Mar 12 2011

Opinion: Inappropriate Roundabouts on Moraga Avenue

Letter to the City Administrator on Proposed Roundabouts for Blair Park/Moraga Canyon

Re: Conventional Roundabouts and Mini-Roundabouts

Dear Mr. Grote,

At the February 24th Planning Commission meeting for the Moraga Canyon Sports Field Project, PRFO Architect Clarence Mamuyac and traffic Engineer Michael Moule misrepresented their new “traffic calming” design solutions for Moraga Avenue-as a “Conventional Roundabout”.   All dialogue & PRFO slide show photos were only of “large” Conventional Roundabouts. Architect Mamuyac, Traffic Engineer Moule and the Public Works Senior Staff report misled and failed to disclose to the Planning Commission Members and the public that the new PRFO elements were specifically for: “Mini-Roundabout” treatments at Red Rock Road (85′ dia) and Maxwelton Road (51′ dia).  Not Conventional Roundabouts-as was depicted in the glossy slide show!
The Federal Highway Administration (FHWA), Cal-DOT, United Kingdom, Canada-all make clear distinctions in classification, size, design, scope and proper locations for both a Conventional Roundabout (over 90′ dia) or a Mini-Roundabout (under 90′ dia).  They are not one and the same.

FHWA and traffic engineer manuals state that Mini-Roundabouts:

  1. Are most effective in low-speed & low vehicle volume environments/neighborhoods.
  2. Where there is a low volume of truck traffic. Moraga Avenue is a truck route.
  3. Should not be installed on major arterials with daily traffic over 10,000 vehicles.  Moraga Avenue daily vehicle count is 11,800-13,000.
  4. Do not install on long grades, hills or gradients over 2-3%. Moraga Avenue gradient is 7%.
  5. To justify a roundabout, side road (Red Rock, Maxwelton,parking lots) flow entry traffic should be a minimum of 500 cars per day or 10-15% of the primary arterial road volume.  (1180 to 1770 side road flow vehicles (day) to justify roundabouts on Moraga Avenue.)
  6. Installing a roundabout simply due to a “development” is highly discouraged.
  7. Required entry speed into a Mini-Roundabout is 15-20 mph. Moraga avg. speed is 35mph.

PRFO traffic mitigation requires a 24/7 50% reduction in vehicle speed on Moraga Avenue.

I believe the City of Piedmont and PRFO are proposing to install two “unsafe” Mini-Roundabout design elements that contradict FHWA & traffic industry guidelines.  I am concerned that the city taxpayers will be exposed to massive legal liability due to this dangerous design.  I believe that the City/PRFO needs additional independent traffic engineering analysis done, plus an updated traffic impact addendum to the FEIR Report.

Mr. Grote, I request that your staff report to the City Council Members for the City Council meeting on March 21 reflect and echo my concerns about this new Mini-Roundabout design.

Thank you,
Neil Teixeira
Piedmont resident

(This letter expresses the personal opinions of the author. All statements made are the opinion of the writer and not necessarily those of the Piedmont Civic Association.)



One Response to “Opinion: Inappropriate Roundabouts on Moraga Avenue”

  1. Thank you, Mr. Teixeira, for your research and effort clarifying that roundabouts will not work. As a 30-year Piedmont resident, I had my doubts that roundabouts were an option on a main traffic artery. You have confirmed that they are not.

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