Arrival Turning Flows
Average Daily Traffic
Entry Width E
Flare Length L'
Entry Radius R
Entry Angle Phi (Ф)
Number of Entry Lanes ne
The HCM capacity model includes ne.
The number of entering streams must be accommodated by the downstream circulating lanes between the central island and the splitter island of the next leg.
The exception is when there are exclusive right turn lanes. In such cases the number of entry lanes excluding the exclusive right turn lanes must not be greater than the number of receiving downstream circulating lanes.
The range is 1 to 4.
The entry lane width is E / ne. The minimum single lane width should not be less than 14 ft (4.25 m) but needs to be wider for trucks. The minimum multilane width is 10 ft (3.0 m).
With narrow multi lanes, trucks straddle the lanes. With very narrow lanes it is obvious that trucks will straddle. With wide lanes, trucks can stay in lane. However, care must be taken to avoid situations where lane widths are such that it looks as though trucks will stay in lane when in fact they will sometimes unexpectedly straddle and clip cars.
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