To calculate Peak Hour Factor, ADT and AADT of any selected road section.

OBJECT: TO CALCULATE PEAK HOUR FACTOR, ADT AND AADT OF ANY SELECTED ROAD SECTION.

PERFORMANCE OBJECTIVE:

By the end of this experiment, students will be able to,

1. Studies carried out at regular intervals to road system performance and trends
   
2. Studies to analyze specific road problems
   

THEORY:

• TRAFFIC VOLUME – The number of vehicles that pass a point during a specified time period (year, day, hour, or less than a hour).
  
• DEMAND VOLUME – The numbers of vehicles that want to, are expected to, or would pass.
  
• CAPACITY – the maximum number of vehicles that can or could pass.
  

Annual Traffic Volumes: The number of vehicles that pass a point in a year

Daily Traffic Volumes: The number of vehicles that pass a point in a day (veh/day, vph) at any day.

Average Daily Traffic (ADT) – The number of vehicles that pass a point in “n” days divided by “n” numbers of days.

Annual Average Daily Traffic (AADT) = ADT x Peak Hour factor

= Total Annual Traffic / 365

Peak Hour Factor: Factor adjusting the Traffic Flow Rate peaking within an hour.

PHF =

Thepeak hour factor(PHF) is the hourly volume during the maximum-volumehourof the day divided by thepeak15-minute flow rate within thepeak hour; a measure of traffic demand fluctuations within thepeak hour.

Thepeak hour factor(PHF) is found by dividing thepeak hourvolume by four times thepeak15 minute volume. The actual (design) flow rate can be calculated by dividing thepeak hourvolume by the PHF, 464/0.86 = 540 pcu/hr, or by multiplying thepeak15 minute volume by four, 4 * 135 = 540 pcu/hr. Since shorter the count, greater is the accuracy of count. Hence to compensate short-interval peaks in traffic volume we use this factor.
PHF = hourly volume divided by 4 x volume in the peak 15 minutes

APPARATUS

1. Data collection sheet
   
2. Safety vests
   
3. Clipboard
   
4. Stopwatch
   
5. Click Counter
   

PROCEDURE

1. Group the students.

2. Get familiar with the roadway approach configuration.

3. Assign each group an intersection.

4. To do this, you obtain a click-counter and position yourself at the intersection. For each fifteen-minute interval, you record the numbers of right-turns, left-turns, straight-through trucks, and straight-through passenger cars.

5. Have students determine:

a) Percentage of vehicles traveling in each direction

b) Percentage of vehicles for each movement (Left, Thru, or Right turn)

6. Draw a figure of each roadway approach configuration.

7. Prepare chart.

Identify the study area.

• For this exercise, select a common intersection
  
• It should be no larger than one observer can handle.
  
  
  

Sketch the Intersection, and determine the Best Position for data collection.

• Two hours of data will be collected at 15-minute intervals.
  
• This collection and analysis techniques.
  
• The actual duration of a Intersection study will vary depending upon the objectives of the study.
  
• Should a Toll Officer wish to know whether Intersection eases Traffic.
  
• A more comprehensive evaluation of the Intersection activity wants a more length study period, possibly covering the entire busy day.
  
• This emphasizes the need for the traffic engineer to define the purpose of the study early in the effort.
  
• This is repeated until the full study time expires.
  

Check the data before leaving the field.

As always, data should be reviewed prior to leaving the field and any discrepancies resolved.

PHF = = ___________

AADT = Total Annual Traffic / 365 = __________

ADT = Vehicular Count/ Days =_____________

Intersection count:

At intersections, vehicles either moves straight (Thru) turn right or left. Intersection count is used for timing traffic signals, designing channelization, planning turning prohibitions, computing proposed alternatives.