Traffic Stream Characteristics
,Flow
There are practically two ways of counting the num
vehicles on a road. One is flow or volume, which is d
as the number of vehicles that pass a point on a h
or a given lane or direction of a highway during a s
time interval.
The measurement is carried out by counting the num
vehicles, nt, passing a particular point in one lan
defined period t.
Then the flow q expressed in vehicles/hour is given by
,Variations of flow/Volume
The variation of volume with time, i.e. month
month, day to day, and hour to hour and within
hour is also as important as volume calculation.
Volume variations can also be observed fr
season to season.
Volume will be above average in a pleasant motor
month of summer, but will be more pronounced
rural than in urban area.
, Types of volume measurements
Since there is considerable variation in the volume of tr
several types of measurements of volume are comm
adopted which will average these variations into a s
volume count to be used in many design purposes.
Average Annual Daily Traffic (AADT): The averag
hour traffic volume at a given location over a full 365
year, i.e. the total number of vehicles passing the site
year divided by 365.
Average Annual Weekday Traffic (AAWT): The av
24-hour traffic volume occurring on weekdays over
year. It is computed by dividing the total weekday t
volume for the year by 260.
,Flow
There are practically two ways of counting the num
vehicles on a road. One is flow or volume, which is d
as the number of vehicles that pass a point on a h
or a given lane or direction of a highway during a s
time interval.
The measurement is carried out by counting the num
vehicles, nt, passing a particular point in one lan
defined period t.
Then the flow q expressed in vehicles/hour is given by
,Variations of flow/Volume
The variation of volume with time, i.e. month
month, day to day, and hour to hour and within
hour is also as important as volume calculation.
Volume variations can also be observed fr
season to season.
Volume will be above average in a pleasant motor
month of summer, but will be more pronounced
rural than in urban area.
, Types of volume measurements
Since there is considerable variation in the volume of tr
several types of measurements of volume are comm
adopted which will average these variations into a s
volume count to be used in many design purposes.
Average Annual Daily Traffic (AADT): The averag
hour traffic volume at a given location over a full 365
year, i.e. the total number of vehicles passing the site
year divided by 365.
Average Annual Weekday Traffic (AAWT): The av
24-hour traffic volume occurring on weekdays over
year. It is computed by dividing the total weekday t
volume for the year by 260.
