ecgd 4121 – transportation engineering i lecture 7 faculty of applied engineering and urban...

ECGD 4121 – Transportation Engineering IECGD 4121 – Transportation Engineering I

Lecture 7Lecture 7

Faculty of Applied Engineering and Urban PlanningFaculty of Applied Engineering and Urban Planning

Civil Engineering DepartmentCivil Engineering Department

11stst Semester 2009/2010 Semester 2009/2010

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Studies of Traffic EngineeringStudies of Traffic Engineering

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ContentContent

• Speed StudiesSpeed Studies

• Volume StudiesVolume Studies

• Travel Time & Delay StudiesTravel Time & Delay Studies

• Parking Studies Parking Studies

Speed StudiesSpeed Studies

Basic Methods:Basic Methods:

• Pneumatic road tube Pneumatic road tube

• Inductive loop detectorsInductive loop detectors

• Video detectorsVideo detectors

• OthersOthers

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Speed StudiesSpeed Studies

Speed characteristics expressed using:Speed characteristics expressed using:

• Average speed (arithmetic mean)Average speed (arithmetic mean)

• Median speedMedian speed

• Modal speedModal speed

• iithth percentile spot speed (85 percentile spot speed (85thth, 95, 95thth))

• Standard deviationStandard deviation

• Basic statistic analysesBasic statistic analyses

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Data SourcesData Sources

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Data AnalysesData Analyses

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Volume characteristics expressed using:Volume characteristics expressed using:

• Average Annual Daily Traffic (AADT)Average Annual Daily Traffic (AADT)

• Average Daily Traffic (ADT)Average Daily Traffic (ADT)

• Peak Hour Volume (PHV)Peak Hour Volume (PHV)

• Vehicle Miles of Travel (VMT)Vehicle Miles of Travel (VMT)

• Vehicle Classification (VC)Vehicle Classification (VC)

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Average Annual Daily Traffic (AADT)Average Annual Daily Traffic (AADT)

• Vehicles per day (VPD) in both directionsVehicles per day (VPD) in both directions

• Expressed as average of 24 hours counts Expressed as average of 24 hours counts

for 365 days (1 year)for 365 days (1 year)

• Used for determining and assigning traffic Used for determining and assigning traffic

trends, feasibility studies, etctrends, feasibility studies, etc

Average Daily Traffic (ADT)Average Daily Traffic (ADT)

• Vehicles per day (VPD) in both directionsVehicles per day (VPD) in both directions

• Expressed as average of 24 hours counts for a Expressed as average of 24 hours counts for a

number of days less than 1 yearnumber of days less than 1 year

• Used for planning, measurement of current Used for planning, measurement of current

demand, evaluate traffic flowdemand, evaluate traffic flow

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hour)peak within minutes 15 during (4)(Volume

VolumeHour Peak FactorHour Peak

PHF

PHVDHVVolumeHourly Design

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)(4)(PV

PHVPHF

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Example: The afternoon peak hour traffic flow Example: The afternoon peak hour traffic flow

data for westbound traffic on a major road are:data for westbound traffic on a major road are:

4:45pm-5:00pm4:45pm-5:00pm 400 vehicles400 vehicles




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Data Analyses:Data Analyses:

• PHV = 400 + 700 + 600 + 400 = 2100 vehiclesPHV = 400 + 700 + 600 + 400 = 2100 vehicles

• PVPV1515 = 700 vehicles = 700 vehicles

• PHF = 2100/(4)(700) = 0.75PHF = 2100/(4)(700) = 0.75

• DHV = 2100/0.75 = 2800 vehiclesDHV = 2100/0.75 = 2800 vehicles

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Methods of Counting:Methods of Counting:

• Manual methodsManual methods

• Automatic methodsAutomatic methods

Surface detectors such as pneumatic road Surface detectors such as pneumatic road

tubes tubes

Subsurface detectors such as magnetic or Subsurface detectors such as magnetic or

electric contact deviceselectric contact devices

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Traffic Volume CountingTraffic Volume Counting

Types of Counts:Types of Counts:

• Cordon countsCordon counts

• Screen line countsScreen line counts

• Intersection countsIntersection counts

• Pedestrian volume countsPedestrian volume counts

• Periodic volume countsPeriodic volume counts

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Adjustment of periodic counts:Adjustment of periodic counts:

• Using data from continuous counting stations Using data from continuous counting stations

we can obtain the Hourly Expansion Factorswe can obtain the Hourly Expansion Factors

• HEF = total volume for 24-hr period/volume HEF = total volume for 24-hr period/volume

for a particular hourfor a particular hour

• HEF is used to expand counts of durations HEF is used to expand counts of durations

shorter than 24 hr to 24-hr volumes (must use shorter than 24 hr to 24-hr volumes (must use

HEF obtained from similar class of roads)HEF obtained from similar class of roads)21



• Daily Expansion Factors (DEF) = Average Daily Expansion Factors (DEF) = Average

total volume for week/average volume for total volume for week/average volume for

particular dayparticular day

• DEF is used to determine weekly volumes DEF is used to determine weekly volumes

from counts of 24-hr duration (must use DEF from counts of 24-hr duration (must use DEF

obtained from similar class of roads)obtained from similar class of roads)

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• Monthly Expansion Factors (MEF) =AADT/ADT Monthly Expansion Factors (MEF) =AADT/ADT

for particular monthsfor particular months

• MEF is used to determine AADT from ADT for MEF is used to determine AADT from ADT for

a given month (must use DEF obtained from a given month (must use DEF obtained from

similar class of roads)similar class of roads)

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Travel Time & Delay StudiesTravel Time & Delay Studies

Studying the route from “A” to “B” to:Studying the route from “A” to “B” to:

• Determine travel timeDetermine travel time

• Determine route efficiencyDetermine route efficiency

• Identify delay locationsIdentify delay locations

• Evaluate “before & after” performanceEvaluate “before & after” performance

• Feasibility studiesFeasibility studies

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Travel-time estimation: The moving car methodTravel-time estimation: The moving car method25


• Requires one testing vehicle, one driver, and Requires one testing vehicle, one driver, and three observers on board.three observers on board.

• Observer #1: counts mean time the testing car Observer #1: counts mean time the testing car takes to travel eastward and westward.takes to travel eastward and westward.

• Observer #2: counts the number of vehicles Observer #2: counts the number of vehicles traveling in opposite directiontraveling in opposite direction

• Observer #3: counts the number of vehicles Observer #3: counts the number of vehicles that overtook and are overtaken by the testing that overtook and are overtaken by the testing vehiclevehicle

• Driver: if possible try to balance the number of Driver: if possible try to balance the number of vehicles (overtaking vs. overtook)vehicles (overtaking vs. overtook)

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• The characteristics of the parking facility and The characteristics of the parking facility and

parking behaviorparking behavior

• Parking facility: full time and part timeParking facility: full time and part time

• Parking behavior: short time and long time – Parking behavior: short time and long time –

rate of use of a parking spacerate of use of a parking space

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Parking StudiesParking Studies

Definition of Parking Terms:Definition of Parking Terms:• Space-hour: the use of a single parking space Space-hour: the use of a single parking space

during a period of time.during a period of time.• e.g., one space-hour can be either one vehicle e.g., one space-hour can be either one vehicle

parked one hour at one parking lot, or two vehicles parked one hour at one parking lot, or two vehicles parked 30 minutes each at one parking lot. parked 30 minutes each at one parking lot.

• e.g., the maximum capacity of a full time (8:00 AM e.g., the maximum capacity of a full time (8:00 AM – 6:00 PM) garage with 200 parking lots is: (200 – 6:00 PM) garage with 200 parking lots is: (200 vehicles)(10 hours) = 2000 veh.hr.vehicles)(10 hours) = 2000 veh.hr.

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Parking StudiesParking Studies

ecgd 4121 – transportation engineering i lecture 7 faculty of applied engineering and urban...

Documents

data sources

studies of traffic engineering

data analysesexample

data analysesdata analyses

westbound traffic

traffic trends

weekaverage volume

average total volume