1. CE 341 Transportation Planning
Data Management & Diagnosis

2. Transport Planning Database
Foundation of effective Transportation Planning
Objectives of Collecting data
Determine existing conditions
Calibration and application of travel forecast models
Evaluation of overall performance of systems operation
Gauging the degree to which planning goals and objectives are achieved
Two major types:
Quantifiable data used in technical analysis
Subjective information (political/decision making process)

3. Traffic Study Data Traffic studies consist of 3 primary activities:
Data Collection: Observing, gathering and recording data.
Data Reduction: Coding, data entry, and tabulation.
Data Analysis: Processing of data to understand the observed situation, diagnosis, and plan improvements.

4. Types of Traffic Data
Traffic data could be grouped into 4 broad categories:
Physical inventories: Street and highway inventories, control devices, parking spaces, roadway conditions.
Population characteristics: Describe various aspects of road users, their vehicles, route, and travel behavior.
Operational parameters: The measures that quantify the characteristics of traffic streams in motion:
volume studies - Speed studies
Travel time studies - Delay studies
4. Special Purpose data:
Accident data - Parking studies
Pedestrian studies - Goods movement &transit studies

5. Sampling Method in Data Collection
It is infeasible - practically and economically- to develop a database consisting of every single element of Target population.
Steps in planning and executing survey:
Establish survey objectives
Define target population
Identify the specific relevant data to collect
Specify the degree of precision required
Determine method to be used in obtaining survey results
Select the sampling procedures and sample size
Pretest the survey
Determine the procedure for analysis for analyzing and summarizing data

6. Types of Sampling Procedures
Simple random sampling: Select units out of population such that each population unit has an equal chance of being drawn.
Sequential sampling: Draw sample from every nth element in the population
Stratified random sampling: divides the population of N units into sub-populations (N1, N2, …, NL) units, according to differences in some defining characteristics. Random samples are then taken within each strata.
Cluster sampling: Grouping sampling units usually on a spatial or geographic basis. Clusters are then selected at random for sample

7. Determining Sample Size
Accuracy of estimates increases with the size of the sample
Degree of accuracy should be balanced against the cost of survey sampling
Determination of sample size involves two major steps:
Make assumption about the population distribution
Make decision about the acceptable limits of error

8. The Normal Distribution
Normal Distribution is defined by:
The Mean: μ
The Standard deviation: σ
Probability of occurrence is measured by the surface area under curve.

9. Confidence Level
Level of confidence (1-α): reflects the percentage of samples falling within the desired limit of error.

10. Sample Size
n = [ z1-α . σ]² d
Where:
n = sample size
d = tolerable margin of error of mean value
σ = standard deviation of population distribution
α = fraction of area under Normal curve representing event NOT within confidence level
z1-α = Standard normal statistics corresponding to the (1- α) confidence level

11. Data Collection Survey Techniques
Street Inventory
Household Travel Behavior
Automatic Traffic Count
Manual Classification Count
Turning Movement Count
Speed Survey
Origin-Destination Survey
a- Roadside interviews
b- Self-completion form
c- Vehicle plate number

12. Street /Highway Inventory
The inventory covers:
street name, classification
transit route & bus stops
abutting land uses and driveways
lighting
curb parking conditions
right-of-way utilization (lanes, sidewalk, pavement, medians)
traffic flow directions
traffic signs details
traffic signal details
traffic safety devices

13. Household Survey Very important in urban transportation planning
Provide timely data on socioeconomic characteristics and travel behavior
Three basic techniques:
personal interviews: Best way of getting info. personal interaction, high response rate, time consuming, expensive
telephone interviews
mail survey

14. HH survey Data Some of HH Records address no of persons>5years
genders
total trips made
motorized vs. non-motorized
persons employed
occupation
income
drivers status
no. of cars
Some Person Records
Age, gender
Occupation, industry, income
Trip made
Origins and destinations made
Purpose “from”
Purpose “to”
Starting time of each trip
Arrival time of every trip
Mode of travel
No. of persons in car
Kind of parking
Principal route of travel

15. Automatic Traffic Count ATC
Mechanically measure volumes
Some types:
Pressure tube (hose)
Magnetic (inductive)
Radar
Video image processing
Temporary
Permanent

16. Time
Volume %
1:00
179
1.1%
2:00
121
0.8%
3:00 83
0.5%
4:00 61
0.4%
5:00 80
6:00
127
7:00
674
4.2%
8:00
1203
7.5%
9:00
1131
7.1%
10:00
1007
6.3%
11:00
1077
6.7%
12:00
1001
6.2%
13:00
988
14:00
925
5.8%
15:00
1069
16:00
1028
6.4%
17:00
989
18:00
920
5.7%
19:00
876
5.5%
20:00
765
4.8%
21:00
630
3.9%
22:00
492
3.1%
23:00
362
2.3%
24:00
251
1.6%
Totals
16038
100.0%
Hourly Flow:
Traffic pattern Peak hour determination Average daily traffic ADT

17. Manual Classification Count MCC
Carried out for short period of time
Normally 15-mn interval
Classify traffic into vehicle classes: cars, taxi, vans, pickup, truck, trailer, bus, etc.
Counting techniques:
Five-bar gate on paper
Tally counter
Hand-held electronic machines

18. Turning Movement Count TMC
Manual count carried out with:
Five-bar gate on paper
Tally counter
Hand-held electronic machines

19. Turning Movement Count TMC
Carried out at junctions during peak periods
15-minute intervals
Record directional volumes
Sometimes classify the turning vehicles (especially left turns into light and heavy vehicles)
Very important for junction operation analysis

20. Speed Survey Three types:
Spot speed for individual vehicles using “radar gun”.
Vehicle in the traffic flow traveling a certain distance using in-vehicle measuring equipment
Speed of Journey

21. Time Vs. Space Mean Speed
Time Mean Speed
Is the average speed of vehicles passing a point over a specific time period.
V=Σt Vt/n
Where:
V = time mean speed
Vt = speed of individual vehicle
n = number of vehicles observed
Space Mean Speed
Is the average speed of vehicles traveling over a measured distance.
V=nL/Σi Ti
Where:
V = space mean speed
ti = travel time of the ith vehicle
n = number of vehicles observed

22. Origin-Destination Survey
Ask drivers the origin and destination of their trips.
Sample-based survey
Selection of unbiased sample
Define Traffic Analysis Zones TAZs, cordons, and screen lines

23. O-D Survey Techniques Roadside Interview:
drivers are stopped at the side of the road
Take safety measures during survey
Self-Completion Forms:
Usually performed via mail
Easier, but sample may not be representative.
License Plate Survey:
Record portion (or all) license plate number and time at some stations
Match license number to determine the origin, destination and path of the vehicle