Roundabout

NCHRP Report 825, Section N, Roundabouts. That section is a simplification of HCM 6th Edition, Chapter 22. Single-lane and two-lane entries use the same steps with different capacity coefficients.

The method estimates circulating flow, entry capacity, volume-to-capacity, control delay, and level of service for each lane, then intersection delay. It assumes no pedestrians, no bypass lanes, and no more than two lanes on an entry or in the circle. U-turns are not a separate movement; add them to the left-turn volume if they need to be included.

cycleLength, lostTimePerPhase, and cycleLengthConfig are not used. opposingCirculatingLanes is required on each approach.