Traffic Volume Counting Methods and Analysis in Civil Engineering

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Lecture. Rana Amir Yousif
Lecture. Sady Abd Tayeh
 
Civil Engineering
Al-Mustansiriyah University
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1.
24 – hour counts normally cover any 24 period.
2.
16 – hour counts  usually from 6 a.m. to 10 p.m.
3.
12 – hour counts  usually from 7 a.m. to 7 p.m.
4.
Peak period counts usually from 7 to 9 a.m. and 4 to 6 p.m.
5.
Weekend counts covering the period from noon (6 p.m.) on  Friday
to noon (or 6 a.m.) on Sunday for the weekends days.
 
Special events should be avoided in counting unless the purpose of  the
Special events should be avoided in counting unless the purpose of  the
counts is to obtain data concerning these unusual conditions.
counts is to obtain data concerning these unusual conditions.
a)
Special events ( holidays, sports, etc.).
Special events ( holidays, sports, etc.).
b)
Abnormal weather conditions.
Abnormal weather conditions.
c)
Temporary closure of streets affecting the volume pattern.
Temporary closure of streets affecting the volume pattern.
d)
Transit or trucking strikes.
Transit or trucking strikes.
 
 
The data collected from traffic volume counts may be presented
in one of several ways, depending on the 
type of count
type of count
conducted
conducted
 and 
primary use of data
primary use of data
.
 
Traffic Flow Maps:- 
Traffic Flow Maps:- 
show traffic volumes on individual routs.
The volume of traffic on each route is represented by width
of a bond, which is drawn in proportion to the traffic
volume it represents.
     When the flow is different on opposite  directions, it is
advisable to provide a separate band for each direction.
 
Intersection Summary Sheets: 
Intersection Summary Sheets: 
graphic representation of all
volume and directions of all traffic movements through the
intersection.
      These volume may be ADT  or PHV depending on the use
of data.
 
Time –Based Direction Charts: 
Time –Based Direction Charts: 
these charts show the hourly,
daily. Monthly or annual variation in traffic volume.
Each volume is percentage of the average volume.
 
Summary Table: 
Summary Table: 
which gives a summary of traffic volume
data such as PHV, VC, and ADT in tabular form.
 
The different vehicle classes have a wide range of static characteristics
such as length, width, etc. and dynamic characteristics such as speed,
acceleration, etc. it is rather difficult to estimate the traffic volume and
capacity of roadway under mixed traffic flow, unless the different
vehicles classes are converted to one common standard vehicle unit. It
is common to consider the passenger car unit (PCU)
PCU                                                 Pcu
PCU                                                 Pcu
1 Buss(≤24 passenger)                       1.25
1 Buss(>24 passenger)                        2-3
1 Truck                                                  2
1 motorcycle                                       0.33
1 Bicycle                                             0.25
1 Buss(≤24 passenger)                        1.25
Light good vehicle                            1-1.25
Heavy vehicle                                        3
 
 
 
 
Solution:
Solution:
No. Passenger cars                     
No. Passenger cars                     
= 8500* (50/100) = 
= 8500* (50/100) = 
4250
4250
No. of busses (25 passenger)     
No. of busses (25 passenger)     
= 8500* (05/100) = 
= 8500* (05/100) = 
425
425
No. heavy vehicle                       
No. heavy vehicle                       
= 8500* (42/100) = 
= 8500* (42/100) = 
4570
4570
No. of motorcycle                       
No. of motorcycle                       
= 8500* (03/100) = 
= 8500* (03/100) = 
255
255
Total equivalent passenger car =
Total equivalent passenger car =
 
 
4250*1+ 425*2.5+3570*3+255*0.33
4250*1+ 425*2.5+3570*3+255*0.33
Total equivalent passenger car =
Total equivalent passenger car =
4250+1062.5+10710+84.15
4250+1062.5+10710+84.15
                                                     = 
                                                     = 
16107
16107
 
 
 
 
Expansion factors, used to adjust periodic counts, are determined either
from continues count or from control count stations.
1.  Hourly expansion factor (HEF
1.  Hourly expansion factor (HEF
)=(total volume for 24 hr period)
)=(total volume for 24 hr period)
/
/
volume for particular hour
volume for particular hour
         These factors are used to expand counts of durations shorter than 24 hr
         These factors are used to expand counts of durations shorter than 24 hr
to 24 hr volume, by multiplying the hourly volume for each hour during
to 24 hr volume, by multiplying the hourly volume for each hour during
the count period by 
the count period by 
HEF
HEF
, for that hour.
, for that hour.
2.  Daily expansion factor (DEF
2.  Daily expansion factor (DEF
)=(average total volume for week)
)=(average total volume for week)
/
/
average
average
 
 
volume for particular day
volume for particular day
         These factors are used to determine weekly volumes from counts of
         These factors are used to determine weekly volumes from counts of
24 hr duration by multiplying the  24-hr volume by 
24 hr duration by multiplying the  24-hr volume by 
DEF
DEF
.
.
3.  Monthly expansion factor (MEF
3.  Monthly expansion factor (MEF
)=( AADT)
)=( AADT)
/ 
/ 
ADT
ADT
 
 
for particular
for particular
month
month
       The AADT for a given year may be obtained from ADT for a given
       The AADT for a given year may be obtained from ADT for a given
month  by multiplying the  volume by 
month  by multiplying the  volume by 
MEF
MEF
.
.
 
 
Estimate the 24 hr volume for Tuesday using factors in
Estimate the 24 hr volume for Tuesday using factors in
Table (1):
Table (1):
=(400*29+535*22.05+650*18.8+710*17.1+650*18.52)/5
=(400*29+535*22.05+650*18.8+710*17.1+650*18.52)/5
= 11959 vpd
= 11959 vpd
Adjust the 24 hr volume for Tuesday to an average for the
Adjust the 24 hr volume for Tuesday to an average for the
week using the factors given in Table (2):
week using the factors given in Table (2):
Total 7-day volume = (11559*7.727)/7
Total 7-day volume = (11559*7.727)/7
=13201 vpd
=13201 vpd
Since the data were collected in May , use the factor shown
Since the data were collected in May , use the factor shown
for May  in Table (3) to obtain 
for May  in Table (3) to obtain 
AADT
AADT
:
:
AADT= 1320*1.394 = 18402
AADT= 1320*1.394 = 18402
 
The design should include the expected future traffic for
period range (15-20) years.
F = (1+growth rate)^no. of years
F = (1+i)^n
Future = present * F
Future = present * (1+i)^n
Where:
N: analysis period ( design and construction life)
Present: current volume
i: growth factor rate (3-12)%Special functions include  in
decimal
 
Future = present * (1+growth rate)^no. of years
Future = 3000 * (1+0.08)^25
            = 20400 veh/day
DHV= 20400 * 0.12 * 0.55
         = 1346 veh/day
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Traffic volume counting in civil engineering involves various methods like traffic flow maps, intersection summary sheets, time-based direction charts, and summary tables. The collected data helps in analyzing peak periods, special events impact, and determining road capacity based on vehicle classes. Understanding different vehicle characteristics and converting them to Passenger Car Units (PCU) is crucial for accurate traffic volume estimation.


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  1. Third Stage Lecture 2 Lecture. Rana Amir Yousif Lecture. SadyAbd Tayeh Civil Engineering Al-Mustansiriyah University 2018-2019

  2. 24 hour counts normally cover any 24 period. 16 hour counts usually from 6 a.m. to 10 p.m. 12 hour counts usually from 7 a.m. to 7 p.m. Peak period counts usually from 7 to 9 a.m. and 4 to 6 p.m. Weekend counts covering the period from noon (6 p.m.) on Friday to noon (or 6 a.m.) on Sunday for the weekends days. 1. 2. 3. 4. 5. Special events should be avoided in counting unless the purpose of the counts is to obtain data concerning these unusual conditions. Special events ( holidays, sports, etc.). Abnormal weather conditions. Temporary closure of streets affecting the volume pattern. Transit or trucking strikes. a) b) c) d)

  3. The data collected from traffic volume counts may be presented in one of several ways, depending on the type of count conducted and primary use of data. Traffic Flow Maps:- show traffic volumes on individual routs. The volume of traffic on each route is represented by width of a bond, which is drawn in proportion to the traffic volume it represents. When the flow is different on opposite advisable to provide a separate band for each direction. directions, it is

  4. Intersection Summary Sheets: graphic representation of all volume and directions of all traffic movements through the intersection. These volume may be ADT or PHV depending on the use of data.

  5. Time Based Direction Charts: these charts show the hourly, daily. Monthly or annual variation in traffic volume. Each volume is percentage of the average volume.

  6. Summary Table: which gives a summary of traffic volume data such as PHV, VC, andADT in tabular form.

  7. The different vehicle classes have a wide range of static characteristics such as length, width, etc. and dynamic characteristics such as speed, acceleration, etc. it is rather difficult to estimate the traffic volume and capacity of roadway under mixed traffic flow, unless the different vehicles classes are converted to one common standard vehicle unit. It is common to consider the passenger car unit (PCU) PCU 1 Buss( 24 passenger) 1.25 1 Buss(>24 passenger) 1 Truck 1 motorcycle 1 Bicycle 1 Buss( 24 passenger) Light good vehicle 1-1.25 Heavy vehicle Pcu 2-3 2 0.33 0.25 1.25 3

  8. Solution: No. Passenger cars No. of busses (25 passenger) No. heavy vehicle No. of motorcycle Total equivalent passenger car = 4250*1+ 425*2.5+3570*3+255*0.33 Total equivalent passenger car = 4250+1062.5+10710+84.15 = 8500* (50/100) = 4250 = 8500* (05/100) = 425 = 8500* (42/100) = 4570 = 8500* (03/100) = 255 = 16107

  9. Expansion factors, used to adjust periodic counts, are determined either from continues count or from control count stations. 1. Hourly expansion factor (HEF)=(total volume for 24 hr period)/ volume for particular hour These factors are used to expand counts of durations shorter than 24 hr to 24 hr volume, by multiplying the hourly volume for each hour during the count period by HEF, for that hour. 2. Daily expansion factor (DEF)=(average total volume for week)/ average volume for particular day These factors are used to determine weekly volumes from counts of 24 hr duration by multiplying the 24-hr volume by DEF. 3. Monthly expansion factor (MEF)=( AADT)/ ADT for particular month The AADT for a given year may be obtained from ADT for a given month by multiplying the volume by MEF.

  10. Hour 6:00-7:00 a.m. 7:00-8:00 a.m. 8:00-9:00 a.m. 9:00-10:00 a.m. 10:00-11:00 a.m. 722 11:00-12:00 a.m. 667 12:00-1:00 p.m. 1:00-2:00 p.m. 2:00-3:00 p.m. 3:00-4:00 p.m. 4:00-5:00 p.m. 5:00-6:00 p.m. Total Daily Volume = 12350 Volume 294 426 560 657 HEF 42 29 22.05 18.8 17.1 18.52 18.71 16.71 14.84 14.77 12.85 13.85 Hour 6:00-7:00 p.m. 7:00-8:00 p.m. 8:00-9:00 p.m. 9:00-10:00 p.m. 10:00-11:00 p.m. 11:00-12:00 p.m. 12:00-1:00 a.m. 1:00-2:00 a.m. 2:00-3:00 a.m. 3:00-4:00 a.m. 4:00-5:00 a.m. 5:00-6:00 a.m. Volume 743 706 606 489 396 360 241 150 100 90 86 137 HEF 16.62 17.49 20.38 25.26 31.19 34.31 51.24 82.33 123.5 137.22 143.6 90 660 739 832 836 961 892

  11. Day of Week Sunday Monday Tuesday Wednesday Thursday Friday Saturday Total weekly volume= 75122 Volume 7895 10714 9722 11413 10714 13125 11539 DEF 9.515 7.012 7.727 6.582 7.012 5.724 6.510

  12. Month Jan. Feb. Mar. Apr. May June July .Aug Sept. Total yearly volume = 28450 Mean average daily volume = 2370 ADT 1350 1200 1450 1600 1700 2500 4100 4550 3750 MEF 1.756 1.975 1.635 1.481 1.394 0.948 0.578 0.521 0.632 Month Oct. Nov. Dec. ADT 2500 2000 1750 MEF 0.948 1.185 1.354

  13. Hour 7:00-8:00 a.m. Volume 400 535 650 710 650 8:00-9:00 a.m. 9:00-10:00 a.m. 10:00-11:00 a.m. 11:00-12:00 a.m.

  14. Estimate the 24 hr volume for Tuesday using factors in Table (1): =(400*29+535*22.05+650*18.8+710*17.1+650*18.52)/5 = 11959 vpd Adjust the 24 hr volume for Tuesday to an average for the week using the factors given in Table (2): Total 7-day volume = (11559*7.727)/7 =13201 vpd Since the data were collected in May , use the factor shown for May in Table (3) to obtainAADT: AADT= 1320*1.394 = 18402

  15. The design should include the expected future traffic for period range (15-20) years. F = (1+growth rate)^no. of years F = (1+i)^n Future = present * F Future = present * (1+i)^n Where: N: analysis period ( design and construction life) Present: current volume i: growth factor rate (3-12)%Special functions include decimal in

  16. Future = present * (1+growth rate)^no. of years Future = 3000 * (1+0.08)^25 = 20400 veh/day DHV= 20400 * 0.12 * 0.55 = 1346 veh/day

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