Arrival Turning Flows
Average Daily Traffic
Entry Width E
Number of Entry Lanes ne
Flare Length L'
Entry Angle Phi (Ф)
Entry Radius R
HCM does not use the entry radius R.
The geometric capacity model has a range for the entry radius of 6 ft (2 m) to infinity.
Entry Radii greater than about 65 ft (20 m) gives little increase in capacity. However reducing R below 65 ft (20 m) reduces capacity at an increasing rate as shown below.
In practice R ranges from about 33 ft (10 m) to about 132 ft (40 m).
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