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The hourly traffic volume divided by the capacity of the segment. Thus, the volume/capacity ratio measure can be assumed to measure capacity sufficiency and delay is a measure of the quality of service.
:
The concepts of capacity and level of service are important for analysis of signalized
intersections. For signalized intersections, capacity and level of service are analyzed
differently because they are defined based on different criteria. The capacity condition for
an intersection is defined by a composite volume/capacity ratio for the critical lane groups
for the intersection. The capacity for the entire intersection is not explicitly defined. The level
of service is based on the average stopped delay per vehicle for the traffic movements in
the intersection, because delay is accepted as the best measure of quality of service to
users.
Composite of V/C Ratio
Thus, the volume/capacity ratio measure can be assumed to measure capacity sufficiency
and delay is a measure of the quality of service.
Capacity is analyzed for each lane group entering the intersection. The capacity for each
lane group is
Ci = Si (gi / C) (9-3)1
where
Ci = capacity for a lane group I, vph
Si = saturation flow rate for lane group I, vphg
g/C = effective green time over cycle time ratio