3.2.8 Validation

Validate existing volumes by checking against field observations, historical traffic counts, traffic volumes from adjacent projects, adjacent land use, and the capacities defined in the HCM. and show the capacities of basic freeway segments, multilane highway segments, and ramps based on the HCM 7th Edition. If there are discrepancies between data points, validate with additional data sources.
Table 3-1: HCM’s Basic Freeway Segment and Multi-Lane Highway Segment Capacities
Free Flow Speed
(mi/h)
Capacity (pc/h/In)
Basic Freeway Segment
Multi-Lane Highway Segment
75
2,400
N/A
70
2,400
2,300
65
2,350
2,300
60
2,300
2,200
55
2,250
2,100
50
N/A
2,000
45
N/A
1,900
Table 3-2: HCM’s Ramp Capacities
Ramp Free Flow Speed
(mi/h)
Capacity (pc/h)
Single-Lane Ramps
Two-Lane Ramps
>50
2,200
4,400
>40-50
2,100
4,200
>30-40
2,000
4,000
>=20-30
1,900
3,800
<20
1,800
3,600