Roundabout Designer

For each leg enter the entry demand v_e and the conflicting circulating flow v_c. The app finds each leg's entry capacity, v/c ratio, control delay, LOS and 95th-percentile queue, plus the overall intersection delay & LOS — with a plan-view diagram and a curated geometry reference.

⭐ Free to analyze · Balance … EP

① Lane configuration & legs

Entry × circulating lane configuration Number of legs (approaches)

HCM 2010 capacity model c = A·e^(−B·v_c). The 2×2 case sums a right- and left-lane capacity. Pick 3 or 4 approach legs.

② Per-leg traffic

For each leg enter the entry demand v_e and the conflicting circulating flow v_c (both veh/h).

v_e — entry (veh/h)

v_c — circulating (veh/h)

v_e — entry (veh/h)

v_c — circulating (veh/h)

v_e — entry (veh/h)

v_c — circulating (veh/h)

v_e — entry (veh/h)

v_c — circulating (veh/h)

③ Geometry reference

Roundabout category (for the geometry table)

Shows indicative geometric dimensions (ICD, circulatory & entry width, entry radius). These are reference ranges — always check the governing roundabout design guide.

🔄 Roundabout performance

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HCM 2010 roundabout analysis

Overall control delay

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Overall LOS

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Worst-leg v/c

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Lane configuration

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Number of legs

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Analysis period T

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Per-leg results

Leg	v_e	v_c	Cap c (veh/h)	v/c	Delay d (s)	LOS	Q95 (veh)

⚠️ Indicative geometry per NCHRP 672 / FHWA / DPWH — verify against the governing roundabout design guide.

Geometry reference — —

Parameter	Indicative value

Roundabout Designer

① Lane configuration & legs

② Per-leg traffic

③ Geometry reference

🔄 Roundabout performance

Per-leg results

Geometry reference — —

Worked solution