Arrival Turning Flows
Average Daily Traffic
Exit Road Width Vx and Lanes nvx
Exit Width Ex and Exit Lanes nex
The exit width excludes gutter pans.
The range is 15 ft (4.6 m) to 54 ft (16.5 m).
Neither the HCM model nor the geometric model use Ex for capacity estimation. However, the geometric model uses it for checks and comparisons with other parameters.
Range = 1 - 4
nex should match the number of exit streams from the circulating lanes. If the exit tapers, the minimum exit taper should be 1:15.
Neither the HCM model nor the geometric model use nex for capacity estimation. However, it is used for checks and comparisons with other parameters.
Lane widths are Ex / nex and these should be a minimum of about 16.5 ft for a single lane exit and about 13 ft for a multilane exit. They should be more generous than entry lane widths and take account of the sharpness of the exit radius with wider lanes with smaller radii.
Ex and nex must accommodate traffic streams from exclusive right turn lanes and semi bypass lanes.
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