CE 341 Transportation PlanningCE 341 Transportation Planning

Data Management & DiagnosisData Management & Diagnosis

Transport Planning DatabaseTransport Planning Database

Foundation of effective Transportation PlanningFoundation of effective Transportation PlanningObjectives of Collecting data Objectives of Collecting data

- Determine existing conditionsDetermine existing conditions- Calibration and application of travel forecast modelsCalibration and application of travel forecast models- Evaluation of overall performance of systems operationEvaluation of overall performance of systems operation- Gauging the degree to which planning goals and Gauging the degree to which planning goals and

objectives are achievedobjectives are achieved Two major types: Two major types:

- Quantifiable data used in technical analysisQuantifiable data used in technical analysis- Subjective information (political/decision making Subjective information (political/decision making

process)process)

Traffic Study Data Traffic Study Data

Traffic studies consist of 3 primary Traffic studies consist of 3 primary activities:activities:

1.1. Data Collection:Data Collection: Observing, gathering Observing, gathering and recording data.and recording data.

2.2. Data Reduction:Data Reduction: Coding, data entry, Coding, data entry, and tabulation.and tabulation.

3.3. Data Analysis:Data Analysis: Processing of data to Processing of data to understand the observed situation, understand the observed situation, diagnosis, and plan improvements. diagnosis, and plan improvements.

Types of Traffic DataTypes of Traffic DataTraffic data could be grouped into 4 broad categories:Traffic data could be grouped into 4 broad categories:

1.1. Physical inventories:Physical inventories: Street and highway inventories, Street and highway inventories, control devices, parking spaces, roadway conditions.control devices, parking spaces, roadway conditions.

2.2. Population characteristics:Population characteristics: Describe various Describe various aspects of road users, their vehicles, route, and travel aspects of road users, their vehicles, route, and travel behavior.behavior.

3.3. Operational parameters:Operational parameters: The measures that quantify The measures that quantify the characteristics of traffic streams in motion: the characteristics of traffic streams in motion:

- volume studiesvolume studies - Speed studies- Speed studies- Travel time studiesTravel time studies - Delay studies- Delay studies

4. 4. Special Purpose data:Special Purpose data:- Accident dataAccident data - Parking studies- Parking studies- Pedestrian studiesPedestrian studies - Goods movement &transit studies- Goods movement &transit studies

Sampling Method in Data CollectionSampling Method in Data Collection

It is infeasible - practically and economically- to It is infeasible - practically and economically- to develop a database consisting of every single develop a database consisting of every single element of Target population.element of Target population.Steps in planning and executing survey:Steps in planning and executing survey:

Establish survey objectivesEstablish survey objectives Define target populationDefine target population Identify the specific relevant data to collectIdentify the specific relevant data to collect Specify the degree of precision requiredSpecify the degree of precision required Determine method to be used in obtaining survey resultsDetermine method to be used in obtaining survey results Select the sampling procedures and sample sizeSelect the sampling procedures and sample size Pretest the surveyPretest the survey Determine the procedure for analysis for analyzing and Determine the procedure for analysis for analyzing and

summarizing datasummarizing data

Types of Sampling ProceduresTypes of Sampling Procedures

Simple random sampling:Simple random sampling: Select units out of Select units out of population such that each population unit has an equal population such that each population unit has an equal chance of being drawn.chance of being drawn.

Sequential sampling:Sequential sampling: Draw sample from every Draw sample from every nnth th element in the populationelement in the populationStratified random sampling:Stratified random sampling: divides the population of divides the population of N units into sub-populations (NN units into sub-populations (N11, N, N22, …, N, …, NLL) units, ) units, according to differences in some defining characteristics. according to differences in some defining characteristics. Random samples are then taken within each strata.Random samples are then taken within each strata.Cluster sampling:Cluster sampling: Grouping sampling units usually on a Grouping sampling units usually on a spatial or geographic basis. Clusters are then selected at spatial or geographic basis. Clusters are then selected at random for samplerandom for sample

Determining Sample SizeDetermining Sample Size

Accuracy of estimates increases with the size Accuracy of estimates increases with the size of the sampleof the sampleDegree of accuracy should be balanced Degree of accuracy should be balanced against the cost of survey samplingagainst the cost of survey samplingDetermination of sample size involves two Determination of sample size involves two major steps:major steps:

1.1. Make assumption about the population Make assumption about the population distributiondistribution

2.2. Make decision about the acceptable limits of Make decision about the acceptable limits of error error

The Normal DistributionThe Normal Distribution

Normal Distribution is defined by:Normal Distribution is defined by:

1.1. The Mean: The Mean: μμ

2.2. The Standard deviation: The Standard deviation: σσProbability of occurrence is measured by the Probability of occurrence is measured by the surface area under curve.surface area under curve.

Confidence LevelConfidence Level

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

Sample SizeSample Size

n = n = [[ zz1-1-αα . . σσ]]²²

ddWhere: Where: n = sample sizen = sample sized = tolerable margin of error of mean valued = tolerable margin of error of mean valueσσ = standard deviation of population distribution = standard deviation of population distributionαα = fraction of area under Normal curve representing event = fraction of area under Normal curve representing event

NOT within confidence levelNOT within confidence level

zz1-1-αα == Standard normal statistics corresponding to the Standard normal statistics corresponding to the (1- (1- αα) confidence level) confidence level

Data Collection Survey TechniquesData Collection Survey Techniques

1.1. Street InventoryStreet Inventory2.2. Household Travel BehaviorHousehold Travel Behavior3.3. Automatic Traffic CountAutomatic Traffic Count4.4. Manual Classification CountManual Classification Count5.5. Turning Movement CountTurning Movement Count6.6. Speed SurveySpeed Survey7.7. Origin-Destination SurveyOrigin-Destination Surveya- Roadside interviewsa- Roadside interviewsb- Self-completion formb- Self-completion formc- Vehicle plate numberc- Vehicle plate number

Street /Highway InventoryStreet /Highway InventoryThe inventory covers:The inventory covers:

street name, classificationstreet name, classification transit route & bus stopstransit route & bus stops abutting land uses and abutting land uses and

drivewaysdriveways lightinglighting curb parking conditionscurb parking conditions right-of-way utilization (lanes, right-of-way utilization (lanes,

sidewalk, pavement, sidewalk, pavement, medians)medians)

traffic flow directionstraffic flow directions traffic signs detailstraffic signs details traffic signal detailstraffic signal details traffic safety devices traffic safety devices

Household SurveyHousehold Survey

Very important in urban transportation planningVery important in urban transportation planning

Provide timely data on socioeconomic Provide timely data on socioeconomic characteristics and travel behaviorcharacteristics and travel behavior

Three basic techniques: Three basic techniques:

1.1. personal interviews:personal interviews: Best way of getting info. Best way of getting info. personal interaction, high response rate, time personal interaction, high response rate, time consuming, expensiveconsuming, expensive

2.2. telephone interviewstelephone interviews

3.3. mail surveymail survey

HH survey DataHH survey Data

Some of HH RecordsSome of HH Records

addressaddress no of persons>5yearsno of persons>5years gendersgenders total trips madetotal trips made motorized vs. non-motorized vs. non-

motorizedmotorized persons employedpersons employed occupation occupation incomeincome drivers statusdrivers status no. of carsno. of cars

Some Person RecordsSome Person Records

Age, genderAge, gender Occupation, industry, incomeOccupation, industry, income Trip madeTrip made Origins and destinations madeOrigins and destinations made Purpose “from”Purpose “from” Purpose “to”Purpose “to” Starting time of each tripStarting time of each trip Arrival time of every tripArrival time of every trip Mode of travelMode of travel No. of persons in carNo. of persons in car Kind of parkingKind of parking Principal route of travelPrincipal route of travel

Automatic Traffic Count ATCAutomatic Traffic Count ATC

Mechanically Mechanically measure volumesmeasure volumes

Some types:Some types:

Pressure tube (hose)Pressure tube (hose)

Magnetic (inductive)Magnetic (inductive)

RadarRadar

Video image Video image processing processing

TemporaryTemporary

PermanentPermanent

Hourly Flow:Hourly Flow:•Traffic pattern Traffic pattern Peak hour determinationPeak hour determinationAverage daily traffic ADTAverage daily traffic ADT

TimeVolum

e %1:00 179 1.1%2:00 121 0.8%3:00 83 0.5%4:00 61 0.4%5:00 80 0.5%6:00 127 0.8%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 6.2%14:00 925 5.8%15:00 1069 6.7%16:00 1028 6.4%17:00 989 6.2%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%

0.0%1.0%2.0%3.0%4.0%5.0%6.0%7.0%8.0%

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3:00

4:00

5:00

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Hour of Day

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aily

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Manual Classification Count MCCManual Classification Count MCC

Carried out for short Carried out for short period of timeperiod of timeNormally 15-mn Normally 15-mn intervalintervalClassify traffic into Classify traffic into vehicle classes: cars, vehicle classes: cars, taxi, vans, pickup, taxi, vans, pickup, truck, trailer, bus, etc.truck, trailer, bus, etc.Counting techniques:Counting techniques:

1.1. Five-bar gate on Five-bar gate on paperpaper

2.2. Tally counterTally counter3.3. Hand-held electronic Hand-held electronic

machinesmachines

CLASSIFICATION COUNTMar Mekhayel

58.4%

17.3%

11.3%

6.0%2.4%

1.1% 3.8%

Private CarTaxiMini Bus / VanPick UpOthersTruckStandard Bus

Turning Movement Count TMCTurning Movement Count TMC

Manual count Manual count carried out with:carried out with:

1.1. Five-bar gate on Five-bar gate on paperpaper

2.2. Tally counter Tally counter

3.3. Hand-held electronic Hand-held electronic machinesmachines

Turning Movement Count TMCTurning Movement Count TMC

Carried out at junctions Carried out at junctions during peak periodsduring peak periods15-minute intervals15-minute intervalsRecord directional Record directional volumesvolumesSometimes classify the Sometimes classify the turning vehicles turning vehicles (especially left turns into (especially left turns into light and heavy vehicles)light and heavy vehicles)Very important for Very important for junction operation junction operation analysis analysis

Speed SurveySpeed Survey

Three types:Three types:

1.1. Spot speed for Spot speed for individual vehicles individual vehicles using “radar gun”.using “radar gun”.

2.2. Vehicle in the traffic Vehicle in the traffic flow traveling a flow traveling a certain distance using certain distance using in-vehicle measuring in-vehicle measuring equipment equipment

3.3. Speed of JourneySpeed of Journey

Time Vs. Space Mean SpeedTime Vs. Space Mean Speed

Time Mean SpeedTime Mean SpeedIs the average speed of Is the average speed of

vehicles passing a point vehicles passing a point over a specific time over a specific time period.period.

V=V=ΣΣtt V Vtt/n/nWhere:Where:V = time mean speedV = time mean speedVVtt = speed of individual = speed of individual

vehiclevehiclen = number of vehicles n = number of vehicles

observedobserved

Space Mean SpeedSpace Mean SpeedIs the average speed of Is the average speed of

vehicles traveling over a vehicles traveling over a measured distance.measured distance.

V=nL/V=nL/ΣΣii T Tii

Where:Where:V = space mean speedV = space mean speedttii = travel time of the i = travel time of the ith th

vehiclevehiclen = number of vehicles n = number of vehicles

observedobserved

Origin-Destination Origin-Destination

SurveySurveyAsk drivers the origin Ask drivers the origin and destination of and destination of their trips.their trips.Sample-based surveySample-based surveySelection of unbiased Selection of unbiased samplesampleDefine Traffic Define Traffic Analysis Zones TAZs, Analysis Zones TAZs, cordons, and screen cordons, and screen lines lines

O-D Survey TechniquesO-D Survey TechniquesRoadside Interview:Roadside Interview: - drivers are stopped at the side of the roaddrivers are stopped at the side of the road- Take safety measures during surveyTake safety measures during survey

Self-Completion Forms:Self-Completion Forms:- Usually performed via mailUsually performed via mail- Easier, but sample may not be Easier, but sample may not be

representative.representative.

License Plate Survey:License Plate Survey:- Record portion (or all) license plate number Record portion (or all) license plate number

and time at some stationsand time at some stations- Match license number to determine the Match license number to determine the

origin, destination and path of the vehicleorigin, destination and path of the vehicle