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Traffic volume studies are conducted to determine the number, movements, and
classifications of roadway vehicles at a given location.
These data helps to identify critical flow time periods, determining the
influence of large vehicles or pedestrians on vehicular traffic flow.
The length of sampling period depends on the type of count being taken and the
intended use of recorded data.
Two methods are available for conducting traffic volume counts: (1) manual and
(2) automatic.
Manual counts are typically used to gather data for determination of vehicle
classification, turning movements, direction of travel, and vehicle occupancy.
Most applications of manual counts require small samples of data at any given
location.
Manual counts are rarely used when the effort and expense of automated equipment
are not justified.
Manual counts are necessary when automated equipment is not available.
Manual counts are typically used for period of less than a day.
Normal intervals for a manual count are 5, 10, or 15 minutes.
Traffic counts during a rush hour of Monday morning and Friday evening rush
hours shows exceptionally high volumes and is not normally used in analysis;
therefore, counts are usually conducted on Tuesday, Wednesday, or Thursday.
The automatic count method provides a means for gathering large amounts of
traffic data.
Automatic counts are usually taken in 1-hour interval for each 24-hour period.
The counts extend for a week, month, or year.
When the counts are recorded for each 24-hour time period, the peak flow period
can be identified.
Automatic counts are recorded using one of three methods: portable counters,
permanent counters, and videotape.
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