A single-lane roundabout has a raised island, splitter islands, entry yield markings and moving circulating traffic. One tested entry stream accepts gaps while upstream circulating vehicles retain priority. Compare queue growth and accepted entries.
• 3D scene parts: Raised central island and truck apron; entry approach and splitter; yield line and priority marker; circulating vehicles and exits; entry performance recorder. • Controls: Upstream circulating arrivals (150–900 veh/h); Tested entry demand (150–900 veh/h); Circulating speed (4–10 m/s); Lane center radius (15–30 m); Required upstream gap (3–8 s); Yield to circulating traffic (0–1 0=fault, 1=obey). • Live readouts: Entry queue (vehicles); Accepted entries (vehicles); Mean departed wait (s); Next circulating arrival (s); Observed entry rate (veh/h); Unsafe accepted gaps (events); Vehicles circulating (vehicles). • Guided experiments: Busy circulating lane; Generous gaps; Ignore yield. • Four tabs (visual laboratory, curves and measurements, experiments, learn and assess), a model-verification run, a timestamped event log and a trial report.
Angular speed ω=v/r Upstream time gap=(2π−wrapped angle)/ω Entry requires upstream gap≥selected gap and downstream clearance≥2 s Deterministic arrival headway=3600/demand Observed entry rate=accepted entries×3600/elapsed time
One entry with an upstream circulating stream, not a full four-leg calibrated capacity model. Constant circular speed and representative approach/exit paths; no lane-changing, pedestrians, stochastic gap distributions or crash dynamics. Arrivals at an occupied spawn are suppressed and counted. Queue cap 120. Radius changes angular travel time; scene radius is normalized and physical radius is in readouts. Fault mode records unsafe gap acceptance. Try the preset experiments, then compare the live readouts with the equations.
Circulating traffic. Entering drivers yield to traffic already circulating.
Yes. Angular speed is linear speed divided by radius.
One entry with an upstream circulating stream, not a full four-leg calibrated capacity model. Constant circular speed and representative approach/exit paths; no lane-changing, pedestrians, stochastic gap distributions or crash dynamics. Arrivals at an occupied spawn are suppressed and counted. Queue cap 120. Radius changes angular travel time; scene radius is normalized and physical radius is in readouts. Fault mode records unsafe gap acceptance.