Mini-roundabouts - A Definitive Guide!

Delegates attending the seminar at Chichester
October 2005

I ran the seminars on mini-roundabouts since 1997, shortly after publication of Mini-roundabouts - Getting them right! This proved a practical way of getting the information over where issues can be debated freely.

These tended to be large events with sometimes over 40 delegates and lasted all day! In America several delegates flew in from neighbouring states to attend (1999).

Experience suggests that numbers should be limited to around twenty to allow for full participation by delegates. The seminars are aimed at key members of staff from highway authorities, consultancies, government bodies and institutions and are held at a suitable venue usually in-house.

At 66 I would not wish to run a full day event. It would now need to be much less formal and about 3 hours with a short break to make it more palatable for everyone. Things have changed a lot; when I started there was virtually no published information - today there is much and the ground can be covered more quickly.


  • To clarify the principles by which roundabouts operate:
    levels of giving way/yielding,
    amount of deflection.
  • To clarify which sites are suitable
  • and which are not!!
  • To clarify design rules
  • To reduce casualty numbers, severity and deaths
  • To save money by eliminating unnecessary features
  • To make the road environment friendly for all road users
  • To introduce roundabouts in forms which will work well throughout the world
Delegates will learn when to use a mini-roundabout, exactly how to design it, when to avoid using one, how it fits in with traffic calming, how to keep costs down, what accidents occur and why, what the likely capacity will be, and where designs are going in the future.

Workshop Agenda - 2 parts

Part 1 Outline of mini-roundabout usage
Important History Early results, how the offside priority rule completely changed roundabout operation; its effect on capacity, safety and land use. 
Site Selection What intersections are appropriate for retrofit with (mini-) roundabouts;
geometry, crash history, congestion and "knotted" traffic movements. 
Design Principles  Examine conflict points, deflection, approach layouts, location and size of central island, location and function of yield lines, 3-way mini-roundabouts, 4-way single, multiple (mini-) roundabouts. Use and design of splitter islands. 

Break for Coffee/Tea Informal discussion 

Part 2  Detailed design aspects
Detailed design Illustrations of a number of designs and how they are done in detail using intended vehicle paths and appropriate deflection.
Flows and Capacity Rule of thumb formula, imbalanced flows, when not to use a mini-rbt, tidal flows, multi-lane use approaches.
  (Mini-) roundabouts in Networks.
Notes: Each presentation will incorporate drawings, graphics, images and video to illustrate the principles of mini-roundabout operation.  Delegates will be free to ask questions during the proceedings rather than to wait until the end of a session; this has been found to enable focussed discussion on a particular topic as it arises.

          * * * * * 

Here are some comments about the earlier seminars:

Thank-you so much for your extremely interesting and well presented seminar that you gave for our members at the Exeter St. Thomas Cricket Club. Watching from the wings it was pleasing to see the members interacting with yourself and each other especially the section with their own designs. I know that the feedback from the questionnaires has been excellent and I'm sure that we may wish to have this presentation again in the future. May I take this opportunity of congratulating you on a well constructed seminar which managed to hold the attention of the staff attending throughout the entire day. Much of your advice and guidance was most interesting... ...many thanks for your excellent seminar. I do not think I can recall a similar presentation which has generated so much interaction and indeed during the following week discussions are still taking place in offices and corridors of this department on various issues raised during Friday.
Charlie Cross
Chairman IHIE South Western Branch
Sam MacNaughton
Head of Consultancy,
Roads and Transport,
The Highland Council, Scotland
Roger Drummond
Principal Engineer,
Shropshire CC

* * * * *


Please contact me for details concerning seminar prices; the price will be based on a fixed fee for up to 20 delegates plus expenses; however, experience has indicated that this formula may not always be appropriate.

For managers considering the problems of balancing limited training budgets, do remember that the savings in making the right scheme choices and detailed designs will pay for the event many times over!

Email me for more information.

Problem sites

We will still try to look at any  problem sites referred to us before the seminars if we have sufficient time to get there. We record stills and video of what is going on and these are played back appropriately during the session. The Engineer whose site we are inspecting should be prepared to present the site briefly at the seminar. He/she should provide overheads/CAD files of the site and any other information to be able to illustrate the difficulties that the site presents.

I often find that "your problem sites" illustrate key issues in the main seminar sessions so images of your sites often appear quite early on!

Previous Seminars (1997-)

Nov 1997

Norfolk CC

Feb 1998 Bedfordshire CC with Luton BC
Mar 1998 Mouchell (Hatfield)
Apr 1998 Wiltshire CC
May 1998 East Sussex CC Manchester (Rochdale)
June 1998 5 seminars in Scotland at: Edinburgh, Alloa, Forfar, Aberdeen & Glasgow
July 1998 Suffolk CC Thurrock, (inc West Essex) Doncaster & South Yorkshire
Sep 1998 Oxfordshire CC South Gloucestershire
Oct 1998 Lancashire CC Dumfries
Nov 1998 Bradford  Worcestershire CC with Hereford Gloucestershire CC
Dec 1998 Poole
Jan 1999 Kirklees (Huddersfield)  Cornwall (2 seminars) IHIE (south-west) at Exeter
Feb 1999 Highland Council (at Inverness)  Northumberland CC Cumbria
Mar 1999 Peter Brett Associates, Reading
Apr 1999 USA Maryland State, Baltimore
Vermont State, Burlington
Michigan State, Lansing
Mott MacDonald, Winchester
May 1999 West Sussex CC Southampton City Council
June 1999 Leicestershire CC (2 seminars)
July 1999 Cambridgeshire CC
Tour of Wales and NW England Newport, Cardiff, Carmarthen, Carnaerffon, Holywell, 
Halton & Shrewsbury (Shropshire CC)
Sept 1999 Seminar for IHIE, London
Oct 1999 West Midlands
Dec 2000

Parkman at Ealing

May 2001 Wiltshire CC (Traffic Calming)
Feb 2002

Cornwall CC (Traffic Calming x 2)

Mar 2002

Derbyshire CC (Mini-roundabouts & Traffic Calming)

June 2002

Northern Ireland 2 seminars (Mini-roundabouts)

Dec 2002

Isle of Man (Mini-roundabouts & Traffic Calming)

Feb 2003

Grand Cayman

Sept 2003

Hants CC (Mini-roundabouts)

Feb 2005

Dunfermline (Mini-roundabouts & Traffic Calming)
Oct 2005

W Sussex (Mini-roundabouts & Traffic Calming)

June 8 2006

 IHIE south-west at Yeovil (Mini-roundabouts)

Sept 19 2006

IHIE south-west at Yeovil (Traffic Calming)

Feb 15 2007

Seminar for IHIE LEEDS (mini-roundabouts)


Nov 2007 Road Safety on Four Continents - Bangkok
Feb 2008 Federal Road Safety Commission, Nigeria International Road Safety Conference, Abuja
May 2008 USA National Conference on roundabout design, Kansas
May 2011 USA National Conference on roundabout design, Carmel

The Future
Despite the considerable need, there has been little demand for the original seminar since Leeds 2007.
The publication of the government TDs and advice documents seem to have taken the place of my work in the UK.
Unfortunately those documents, as identified on this site, are seriously flawed. We are not seeing any improvements in the poor designs that have been scattered all over the UK with the result that mini-roundabouts are now viewed by a sceptical public in much the same way that modern roundabouts in America were perceived by their public. Worse, I continue to hear comments that our guidelines are not being used by others because they are perceived to be poor. (Perhaps I have done a good job here warning [the Americans] off from using our design rules and criteria!)

I remain available to help sort out any sites that have given problems and that has been the thrust of most of my work in the last few years. In time I hope to be able to add before and after images of them with comments on the design aspects that have caused the problems.

If you identify with this please contact me and I will do what I can to help. This may include a focussed presentation but is now unlikely to be a full training day of the type that I was doing until 2007.

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