traffic volume-study-presentation-final

Ahsanullah University of Science And Technology Department of Civil Engineering

Course No: CE 452Course Name: Transportation Engineering Lab-II4th Year 2nd semester (Section: B)

APresentation

oNTraffic Volume Study

Presented By: Group-03

Group members:

1. Tasrufa Tahsin (11.01.03.074)2. Md. Salim Mia (11.01.03.075)3. Faruk Patowary (11.01.03.079)4. Rumana Samad (11.01.03.082)5. Aqib Jishan (11.01.03.112)6. Raqib Al Mahmood (11.01.03.115)7. Mizanur Rahman Sharif (09.01.03.002)8. Farhan Shihab (10.01.03.085)

Traffic Volume Study

What is traffic volume Study?

Traffic Volume Study: The term traffic volume study is also known as traffic flow survey or simply the traffic survey. It is defined as the procedure to determine mainly volume of traffic moving on the roads at a particular section during a particular time. Volume is basically number of vehicles or persons passing a point during a specified time period which is usually one hour but may be less than that. It means during a period of time, it may be fifteen minutes, it may be half an hour, it may be even sixty minutes or one hour and how many vehicles or persons are passing a point during that particular time period is known as volume. Traffic volume study is used for traffic planning of a particular road or area. Traffic stream composition of a particular road can be known from traffic volume study.

Objectives of traffic volume study

General

Objectives

Geometric Design Of

The Roadway

Dynamic

Traffic Management And Control

Traffic Planning

Improvement

Of The Level Of Service Of The

Roadway

Scope of traffic volume study

To Check The Existing Level Of Service Of The Road

Magnitudes, Classification, Proportion And Directional

Distribution Of Vehicular Flow

Study Of The Flow Fluctuation Of Different Approaches

Traffic Design, Planning And Control Measures

Scope

Some important definitions related to traffic volume study

Average Daily Traffic (ADT): Average daily traffic or ADT, and sometimes also mean daily traffic, is the average number of vehicles two-way passing a specific point in a 24-hour period, normally measured throughout a year. ADT is not as highly referred to as the engineering standard of AADT which is the standard measurement for vehicle traffic load on a section of road, and the basis for most decisions regarding transport planning, or to the environmental hazards of pollution related to road transport.

Annual Average Daily Traffic (AADT): Annual average daily traffic, abbreviated AADT, is a measure used primarily in transportation planning and transportation engineering. Traditionally, it is the total volume of vehicle traffic of a highway or road for a year divided by 365 days. AADT is a useful and simple measurement of how busy the road is. Newer advances from traffic data providers are now providing AADT by side of the road, by day of week and by time of day.

Passenger Car Equivalent (PCE): Passenger Car Equivalent (PCE), is a metric used in Transportation Engineering to assess traffic flow rate on a highway. A Passenger Car Equivalent is essentially the impact that a mode of transport has on traffic variables (such as headway, speed, density) compared to a single car. Highway capacity is measured in PCE/hour daily. Passenger Car Equivalent is also sometimes used interchangeably with Passenger car unit (PCU).


Directional Distribution (DD): The directional distribution is simply the distribution or split of total traffic volume in two opposite directions in particular time period. It is commonly expressed in terms of percentage of total traffic in the heavier direction of travel.

Average Weekly Traffic (AWT): It is the average of 24-hour traffic volume which is occurring on weekdays for some period less than one year. Annual Average Weekly Traffic (AAWT): AAWT is the average 24-hr traffic volume occurring on weekdays over a full 365-day year.

Design Hourly Volume: It is the economic hourly flow of future year, which is used for designing geometric features of roadway. It is chosen in such a way that during the design period it should not be exceeded too often or too much.

Rate of Flow: Rate of flow is used to express an equivalent hourly rate for vehicles passing a point along a roadway or for traffic during an interval less than 1-hr (usually 15min).

Saturation flow: The maximum hourly rate of an approach at a signalized junction.


Service flow rate: The maximum hourly rate of traffic flow of a roadway section during a given period under prevailing roadway condition.

Forced flow: When lane changing opportunity decreases with increasing traffic volume and drivers are forced to follow slow leaders.

Free flow: When drivers face no restriction in driving and can maintain their desired speeds.

Peak flow: Flow at peak periods.

Off-peak flow: Flow at off-peak/lean periods.

Stable/ Steady flow: When demands are well below the roadway capacity and the average rate of flow remains almost constant with time.

Unstable flow: When demand is at or near or exceeds the roadway capacity and the average rate of flow fluctuates largely with time.

Contra flow: For repair works; an arrangement on a large road by which traffic going in both directions uses only one side of the road. For bus priority; a special arrangement on one-way street by which only bus is allowed to go in opposite direction.

Tidal flow: When traffic flows in both direction exhibit unbalanced characteristics at peak periods viz. morning rush at in-bound lanes due to commuter traffic and in the evening the same is true for the out-bound lanes.

Traffic Volume count

Traffic volume counts are basic to all phases of highway development and operation. No other single reference tells an engineer as much about a road as the number of vehicles which use it.

Traffic counts are the major source of traffic data. Traffic counts are very specific in that they only apply to one location and to the time period for which they have been obtained. Some of the major types of traffic counts in general use by engineers are annual counts, peak hour counts, turning movement counts and classification counts.

Methods of traffic volume count

1. Manual observation2. Automatic recording

Manual observation

Counting is done by trained personnel Used when the effort and expense of automated equipment are not justified Used to gather data for determination of vehicle classification, turning movements,

direction of travel, pedestrian movements, or vehicle occupancy Usually used for counting period less than a day

Manual Count Recording Methods

Manual counts are recorded by using one of the following three methods: 1. Tally Sheets2. Mechanical Counting Boards3. Electronic Counting Boards

Tally Sheets:Recording data onto tally sheets is the simplest means of conducting manual counts. The data can be recorded with a tick mark on a pre-prepared field form. A watch or stopwatch is necessary to measure the desired count interval

Mechanical Counting Boards:Mechanical count boards consist of counters mounted on a board that record each direction of travel. Common counts include pedestrian, bicycle, vehicle classification, and traffic volume counts. Typical counters are push button devices with three to five registers. Each button represents a different stratification of type of vehicle or pedestrian being counted.

Electronic Counting Boards:Electronic counting boards are battery-operated, hand-held devices used in collecting traffic count data. They are similar to mechanical counting boards, but with some important differences. Electronic counting boards are lighter, more compact, and easier to handle. They have an internal clock that automatically separates the data by time interval. Special functions include automatic data reduction and summary. The data can also be downloaded to a computer, which saves time.

Automatic recording

Counting is done by sophisticated electronic devices and detectors

Used for gathering large amount of traffic data

Used when the effort and expense of automated equipment are justified

Counting is usually done in 1 hour intervals for each 24 hours period Counting may be done continuously for a

week, month or a year

Automatic Count Recording Method

Automatic counts are recorded using one of the following three methods: 1. Portable Counters 2. Permanent Counters3. Videotape.

Portable Counters:Portable counting is a form of manual observation. Portable counters serve the same purpose as manual counts but with automatic counting equipment. The period of data collection using this method is usually longer than when using manual counts. The portable counter method is mainly used for24-hour counts. Pneumatic road tubes are used to conduct this method of automatic counts.

Permanent Counters:Permanent counters are used when long-term counts are to be conducted. The counts could be performed every day for a year or more. The data collected may be used to monitor and evaluate traffic volumes and trends over a long period of time. Permanent counters are not a cost-effective option in most situation. Few jurisdictions have access to this equipment.

Videotape:Observers can record count data by videotaping traffic. Traffic volumes can be counted by viewing videotapes recorded with a camera at a collection site. A digital clock in the video image can prove useful in noting time intervals. Videotaping is not a cost-effective option in most situations. Few small jurisdictions have access to this equipment

commonly used detectors in automatic counting

Pneumatic TubesThese are tubes placed on the top of road surfaces at locations where traffic counting is required. As vehicles pass over the tube, the resulting compression sends a burst of air to an air switch, which can be installed in any type of traffic counting devices. Air switches can provide accurate axle counts even when compressions occur more than 30 m from the traffic counter.

Inductive LoopsInductive loop detector consists of embedded turned wire from which it gets its name. It includes an oscillator, and a cable, which allows signals to pass from the loop to the traffic counting device. The counting device is activated by the change in the magnetic field when a vehicle passes over the loop. Inductive loops are cheap, almost maintenance-free and are currently the most widely used equipment for vehicle counting and detection.

commonly used detectors in automatic counting

Weigh-in-Motion SensorA variety of traffic sensors and loops are used world-wide to count, weigh and classify vehicles while in motion, and these are collectively known as Weigh in Motion (WIM) sensor systems. Whereas sensor pads can be used on their own traffic speed and axle weighing equipment, they are trigged by “leading” inductive loops placed before them on the roadbed.

Radar DetectorsRadar detectors actively emits radio-active signals at frequencies ranging from the ultra-high frequencies (UHF) of 100 MHz to 100 GHz and can register vehicular presence and speed depending upon signals returned upon reflection from the vehicle.

Types of volume count

1. Cordon Counts:When information is required on vehicle accumulation within an area, such as the central business district (CBD) of a city, particularly during a specific time, a cordon count is undertaken. The area for which the data are required is cordoned off by an imaginary closed loop; the area enclosed within this loop is defined as the cordon area.

2. Screen Line Counts:In screen line counts, the study area is divided into large sections by running imaginary lines, known as screen lines, across it. In some cases, natural and man-made barriers, such as rivers or railway tracks, are used as screen lines. Traffic counts are then taken at each point where a road crosses the screen line. It is usual for the screen lines to be designed or chosen such that they are not crossed more than once by the same street.


3. Cordon and Screen Line Counts:

Both Cordon and Screen Line counting methods are done simultaneously

4. Intersection Counts:Intersection counts are taken to determined vehicle classification through movements and turning movements at intersections. These data are used mainly in determining phase lengths and cycle times for signalized intersections, in the design of channelization at intersections, and in the general design of improvements to intersections.


5. Pedestrian Volume Counts:Volume counts of pedestrians are made at locations such as subway stations, mid-blocks, and crosswalks. The counts are usually taken at these locations when the evaluation of existing or proposed pedestrian facilities is to be undertaken. Such facilities may include pedestrian overpass or underpasses.

6. Periodic Volume Counts:In order to obtain certain traffic volume data, such as AADT, it is necessary to obtain data continuously. However, it is not feasible to collect continuous data on all roads because of the cost involved. To make reasonable estimates of annual traffic volume characteristics on an area-wide basis, different types of periodic counts, with count durations ranging from 15 min to continuous, are conducted; the data from these different periodic counts are used to determine values that are the used to estimate annual traffic characteristics.The periodic counts usually conducted are continuous, control, or coverage counts.

Key steps of Manual and Automatic Count

Perform Necessary Office Preparations

Select Proper Observer Location

Label Data Sheets And Record Observations

Perform Necessary Office Preparations

Deploy And Calibrate Data Collection Equipment

Check Data And Retrieve Equipment

Manual Method Automatic Method

Traffic volume study location

Panthapath to Russel Square Link Road

Method of Counting : Manual

Equipment Used for Counting Stopwatch Handmade Data Sheets Pencil Clipboard Hand Tally Counter

Number of Enumerator There were 8 enumerators in the group. Individual was appointed to count one or more than one classified vehicles.

Collected Data

Date : 30 January, 2014

Day : Thursday Time: 11:00-11:30 am

Counting Period: 30 min

Group No : 3

Direction: Panthapath to Russell Square

Location : Russell Square Intersection

Weather Condition: Mild and sunny

Vehicle Classification Observed Vehicle No

Bus 3

CNG 112

Car 240

Jeep, Microbus, Ambulance 145

Motorcycle (MC) 145

NMV 350

Utility 20

Truck 3

Total = 1018

Traffic Stream Composition(Panthapath to Russel Square link Road)

Number of Different Vehicles Percentage of Different Vehicles

Service flow rate(Panthapath to russel square link road)

Service Flow Rate = 1545.5 PCU/hr ≈ 1546 PCU/hr

Level of service (LOS)Group: 03

Level Of Service (LOS) Service Flow Rate (PCU/Hr)

A 600

B 700

C 900

D 1200

E 1400

F >1400

Service flow rate of different groups

ADT and AADT (East to West) Provided Values:

HEF (9:00-10:00 am) = 18.80HEF (10:00-11:00 am) = 17.11HEF (11:00-12:00 pm) = 18.52DEF (Thursday) = 7.012MEF (January) = 1.756

Estimated 24-hr volume for Thursday using HEF = (1346*18.80+1405*17.11+1546*18.52)/3 = 25992.09 PCU/24-hr ≈ 25992 PCU/24-hr Adjust the 24-hr volume for Tuesday to an average volume for the week using the daily expansion factors. Total Weekly Volume = 25992*7.012 = 182255.9 PCU/week ≈ 182256 PCU/week Average 24-hr volume or Average Daily Traffic, ADT (East to West) = 182256/7 = 26036.57 PCU/24-hr ≈ 26037 PCU/24-hr Annual Average Daily Traffic, AADT (East to West) = 26037*1.756 = 45720.97 PCU/day ≈ 45721 PCU/day

ADT and AADT (West to east)

Estimated 24-hr volume for Thursday using HEF = (1822*18.80+1672*17.11+1682*18.52)/3 = 31337.39 PCU/24-hr ≈ 31337 PCU/24-hr Adjust the 24-hr volume for Tuesday to an average volume for the week using the daily expansion factors. Total Weekly Volume = 31337*7.012 = 219735.04 PCU/week ≈ 219735 PCU/week Average 24-hr volume or Average Daily Traffic, ADT (West to East) = 219735/7 = 31390.71 PCU/24-hr ≈ 31391 PCU/24-hr Annual Average Daily Traffic, AADT (West to East) = 31391*1.756 = 55122.59 PCU/day ≈ 55123 PCU/day

Directional distribution

From the π-Diagram it is seen that 54.64% vehicles of total traffic volume go from West to East while 45.36% vehicles go from East to West. It signifies that in a day more vehicles travel from Dhanmondi residential area to Panthapath and Sonargaon commercial area than from opposite direction. Directional distribution also varies during morning and evening due to commuter traffic.

Direction Time PCU/hr Avg.

PCU/hr

Directional

Distribution

E to W

9:00-9:30 am 1346

1432.33

45.36%10:30-11:00

am

1405

11:00-11:30

am

1546

W to E

9:00-9:30 am 1822

1725.33

54.64%10:30-11:00

am

1672

11:00-11:30

am

1682

Flow fluctuation On a given roadway, the volume of traffic fluctuates widely with the time. Such variations during a day, week or year tend to be cyclical and to some extent predictable. The nature of the pattern of variation depends on the type of road facility. Urban arterial flow is, for example, characterized by pronounced peaks during the early morning and late afternoon hours, due primarily to commuter traffic. Rural roads tend to experience less pronounced daily peaks, but they may accommodate heaviest traffic flow on weekends and holidays because of recreational travel. Flow fluctuation curve of a road represents the variation of flow throughout a day. 24-hr traffic volume data is required to develop a flow fluctuation curve.

Flow fluctuation analysis

Time East to West(Flow Rate, PCU/hr)

West to East(Flow Rate,

PCU/hr)

East to West(ADT)

West to East(ADT)

East to West( % of ADT )

West to East( % of ADT )

9:00-10:00 am 1346 1822 26037

31391

5.17% 5.80%

10:30-11:00 am 1405 1672 5.40% 5.33%

11:00-12:00 pm 1546 1682 5.94% 5.36%

Flow fluctuation curve(Panthapath to Russel Square link road)

4.60%

4.80%

5.00%

5.20%

5.40%

5.60%

5.80%

6.00%

6.20%

% Of ADT VS TIME

East to West West to East

9:00-10:00 AM 10:00=11:00 AM 11:00-12:00 PM

% o

f AD

T

From the % Of ADT VS TIME flow fluctuation curve it is seen that during time period 9:00-10:00 am, percentage of ADT passing from West to East is greater than East to West and gradually decreases with time. On the other hand, percentage of ADT from East to West is minimum at this period and increases with time. During 10:00-11:00 am, the percentage of ADT from both East to West and West to East is more or less same.

9 : 0 0 - 1 0 : 0 0 A M 1 0 : 0 0 - 1 1 : 0 0 A M 1 1 : 0 0 - 1 2 : 0 0 A M0

200

400

600

800

1000

1200

1400

1600

1800

2000

Flow Rate Vs TimeEast to West West to East

Time

Flow

Rat

e (P

CU/H

r)

Flow fluctuation curve(Panthapath to Russel Square link road)

In the FLOW RATE VS TIME flow fluctuation graph, we see that the service flow rate from West to East is always greater than the service flow rate from East to West. It signifies that volume of vehicles travelling from Russel Square to Pathapath direction is always remains greater than the opposite direction. It is also seen from the graph that in both direction a peak is observed during the period 9:00-10:00 am. This morning peak occurs due to commuter traffic travelling from nearby residential areas.

Recommendations

Non Motorized Vehicles (NMV) Shouldn’t Be Allowed In This Road

Road Side Parking Should Be Banned or Toll May Be Collected To Discourage Parking

Recommendations

Amount Of Public Transport Should Be Increased

Road Side Non-motor Activities Should be Prohibited

Recommendations

Scattered And Haphazard Pedestrian Crossing Should Be Discouraged And Prohibited

Foot Over Bridges Should Be Constructed At Important Points For Pedestrian Crossings

Recommendations

Optimum traffic signal system should be introduced During rush hours or tidal flow, lanes may be rearranged Number of lanes should be based on directional distribution Signal timing should also be set from directional distribution Entry of NMV should be restricted during peaks obtained from flow fluctuation curve Right of way may also be restricted to avoid congestion

Limitations

Limited and unskilled enumerators. Time and Resources are Limited Insolent Surveyors Manual method of counting, which is unreliable and irreversible Short-term (30 minute) data collection CCTV footage or Camera recording is not available Expansion factors used for the calculation of ADT were developed

for a rural primary road. Proper enforcement of traffic regulation is not obtained For Flow Fluctuation Curve weekly 24 hours is needed. But due to

time and manpower constraint it was not possible.