| LOS |
|
|
A
V/C ratio >.59
0-10 seconds |
Indicates a relatively free
flow of traffic, with little or no limitation on vehicle movement or
speed. |
|
B
V/C ratio .60 - .69
10-20 seconds |
Describes a steady flow of
traffic, with only slight delays in vehicle movement and speed. All queues
clear in a single signal cycle. |
|
C
V/C ratio .70 - .79
20-35 seconds |
Denotes a reasonably steady,
high-volume flow of traffic, with some limitation on movement and speed,
and occasional backups on critical approaches. |
|
D
V/C ratio .80 - .89
35-55 seconds |
Designates
the level where traffic nears an unstable flow. Intersections still
function, but short queues develop and cars may have to wait through one
cycle during short peaks. |
|
E
V/C ratio .90 - .99
55-80 seconds |
Represents traffic
characterized by slow
movement and frequent (although momentary) stoppages. This type of
congestion is considered severe, but is not uncommon at peak traffic
hours, with frequent stopping, long-standing queues, and blocked
intersections. |
|
F
V/C ratio 1.00+
>80 seconds |
Describes unsatisfactory
stop-and-go traffic (Marin freeway today)
characterized by “traffic jams” and stoppages of long duration.
Vehicles at signalized intersections usually have to wait through one or
more signal changes, and “upstream” intersections may be blocked by
the long queues. |
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