Have tou checked on Highway Capacity Manual 2010, CHAPTER 21, roundabouts?

The chapter has about 40 pages of methodologies and examples of calculation

it may be useful

Sorry!

Highway Capacity Manual 2010, VOLUME 3, CHAPTER 21, roundabouts

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Deffinitelly check the HCM 2010 (or older), but be carefull about the type od circular traffic discussed.  Generally, the place to be checked is the entry to the roundabout from a street.  A different case is for a classical, that is collision point free, roundabout, - there the entrance is smooth and you have to check the interweaving of cars.

I agree with Jeremi Rychlewski. And we must consider that, as any manual, the excellent HCM shows only examples that then then we adapt to the reality.

I think Synchro 7 can analyze the traffic behavior  around the roundabout with visual animation. Also, it can estimate the capacity and LOS for roundabout .

Synchro 7 could be useful for the assessment of roundabouts but it's necessary take into account that the model is based on the Australian roundabout design, where there are not lane changes in the circle.

Another option is aaSIDRA to evaluate a roundabout as an isolated intersection. This model is based on gap acceptance theory and reports HCM 2000 level of service (using delay), lane by lane.

Vissim allows to observe a more real behavior at roundabouts, but calibration process requires significant time and critical gap data per lane. Once the model is calibrated, it's possible to determine the average delay per approach and then use the HCM 2010 level of service criteria for multi-lane roundabouts in order to determine such level of service (per approach, not for the whole roundabout).

I hope this can help you.

Lenin B.

Dear Dr.khalid

Good question and very useful information from all researchers.

Best regards