1) The document summarizes UK research on roundabouts, focusing on the implementation and validation of the priority rule for circulating traffic. 2) Extensive research in the 1960s-1980s involving over 500,000 vehicles and 1427 accidents established the priority rule and developed relationships between traffic capacity and roundabout design. 3) This empirical methodology is now used internationally by governments, universities, and transportation organizations to guide roundabout engineering, design, and analysis.

1. UK Roundabout Research Presented by Mike HuttTransportation Division

2. UK Roundabout Research Agenda Why the Priority Rule? 1 Implementation of the Priority Rule 2 Ensuring robust results 3 Research into capacity relationships 4 International validation 5

4. No set rules for driver behaviour

5. “Locked” Roundabouts Common

7. Signal Control trialled at Roundabouts

9. Implementation of the Priority Rule What illustrates priority most obviously?

10. Implementation of the Priority Rule Frank C. Blackmore’s research faced strong opposition, the key to the success of the Priority Rule was the use of white painted road markings across the entry to which the rule applied

12. 11,000 minutes of capacity operation

13. 500,000 vehicles observed

14. 1427 injury accidents studied

15. 431 junction years of accident data

16. Over 5 years of accident data at each site

17. Research duration 10 – 12 years

18. Equivalent current cost of approximately $20 million (US)

19. Research Into Capacity Relationships Rod M. Kimber’s research into the traffic capacity relationships at roundabouts had the specific aim of producing reliable results for use by a Traffic Engineer

20. Research Into Capacity Relationships Numerous researched equations were used to build the now world renowned International Empirical Methodology

22. Universities to teach Roundabout Engineering

23. Multi-national organisations for accurate results